Synthesis Example

C12H22N5O6X -> [CHX +] C11H21N5O6
Hydrolysis of polystyrene-bound protected amino acids and peptides has been achieved using dimethylaminoethanol or triethanolamine, dimethylformamide and aqueous sodium hydroxide and the reaction is accelerated by ultrasound. Rapid cleavage and excellent ields of the products in high purity, without racemization, are the main advantages of the method.

C7H9NO2S + C6H12O3 -> [C2H10O3 +] C11H11NO2S
Phosphorous pentoxide is the catalyst of choice for the facile conversion of primary amines, aromatic amines, sulfonamides and primary amides into the corresponding N-substituted pyrroles from 2,5-dimethoxytetrahydrofuran.

C14H14S [+ O] -> C14H14OS
A new and efficient method for oxidising sulfides selectively to sulfoxides has been developed with atmospheric oxygen, in the presence of isobutyraldehyde and catalysed by Ni-II complexes such as bis(1,3-bis-(p-methoxyphenyl)-1,3-propanedionato)nickel, ( i(dmp)(2)), and bis(acetylacetonato)nickel, (Ni(acac)(2)).

C13H17NO4S -> [C6H8OS +] C7H9NO3
Electrogenerated bases promote the carboxylation of NH-protic carboxamides bearing a leaving group at the position 2 to give oxazolidine-2,4-diones. The process is believed to involve acid-base reaction with the substrate, carboxylation of its conjugate b se to the corresponding carbamate and ring-closure following intramolecular S(N)2 reaction. A variety of oxazolidine-2,4-diones, including clinically used trimethadione(R) and malidone(R), have been prepared in high to excellent yield, which established t e scope and generality of this new ring-forming process.

C15H24O5 [+ C2H4] -> C17H28O5
A simple and efficient method for the preparation of ethers (3a-f) of dihydroartemisinin (2) has been developed using chlorotrimethylsilane as a catalyst.

C7H12O3 + C3H9N3Si -> [C3H8Si +] C7H13N3O3
Ring opening of epoxides with trimethylsilyl azide is catalysed by ytterbium triisopropoxide at room temperature in THF, giving the corresponding vicinal azide alcohols in very high yields.

C28H48 -> C28H48
Sterically congested thiiranes having a 2,4,6-tri-t-butylphenyl group were synthesized by the reactions of (2,4,6-tri-t-butyl)thiobenzaldehyde with sterically hindered diazo compounds. Thermal desulfurization of the most congested thiirane, 2,2-di-t-butyl 3-(2,4,6-tri-t-butylphenyl)thiirane (15c), did not proceed even upon using highly reactive reagents, such as hexamethylphosphorous triamide or organolithiums. The photoreaction of 15c did not give the corresponding styrene, but afforded several products c ntaining 2,4,6-tri-t-butylbenzo(b)thiophene and Dewar benzenes, 2,2-di-t-butyl-3-(3,4,6-tri-t-butylbicyclo(2.2.0)hexa-2,5-dien- 2-yl)thiirane and 2-t-butyl-3,3-dimethyl-1-(1,3,5-tri-t-butylbicyclo(2.2.0)hexa-2,5-diene-2-yl)-1-butene (24), the latter of wh ch is the first example for a vinyl-substituted Dewar benzene. Compound 24 has a unique reactivity, giving a rearrangement product, 2-t-butyl-3,3-dimethyl-1-(1,3,5-tri-t- butylbicyclo(2.2.0)hexa-2,5-diene-2-yl)-1-butene on thermolysis.

C13H12O -> [H2 +] C13H10O
A soluble Ru(VII)/Ru(IV) redox system in MeCN/H2O(9/1 v/v)-Bu(4)NOH-(Pt/Pt) was found to be a mild oxidizing method for the electrochemical conversion of primary and secondary alcohols into their corresponding aldehydes and ketones under basic conditions.

C16H17O5P + C5H10O -> [C12H11O4P +] C9H16O2
A new Horner-Emmons reagent, ethyl diphenylphosphonoacetate 1 was prepared from triethyl phosphonoacetate, PCl5, and phenol in 60%, overall yield. Horner-Emmons reaction of 1 with aldehydes in the presence of Tritons(R) B or NaH in THF gave the Z-unsatura ed esters in 89-93% selectivity in almost quantitative yields. Furthermore, 1 showed up to 99% Z-selectivity under Still's condition (KHMDS/18-crown-6).

C6H8N2 + C14H10O2 -> [H4O2 +] C20H14N2
Quinoxalines were obtained by the condensation of alpha-diones with o-diaminobenzenes without solvent under focussed microwave irradiation.

C70H99Cl2NO37 [+ O] -> [H2 +] C70H97Cl2NO38
A horseradish peroxidase-catalyzed oxidation of nitroso- and hydroxylamino derivative of the antibiotic Everninomicin (EVN) by hydrogen peroxide has been carried out. Due to the very low solubility of the substrate in water, the oxidation was performed in 50% aqueous/dioxane mixture. Despite the high concentration of the co-solvent the enzyme remained selective and highly active. The conversion of the hydroxylamino-EVN 1 to nitro-EVN 3 was quantitative and proceeded via the nitroso-EVN intermediate 2. The xidation with (H2O2)-O-18 indicated that oxygen on the nitro group derived predominantly from the hydrogen peroxide, thereby providing a strong evidence for a direct ferryl-oxygen transfer.

C5H6BrN3O2 + C4H9NO -> [HNO2 +] C9H14BrN3O
Treatment of 4-substituted 3,5-dimethyl-1-nitro-1H-pyrazoles 1 and 10a-c with secondary amines in acetonitrile, in the presence of 1,8-diazabicyclo(5.4.0)undec-7-ene (DBU), affords the novel dialkylaminomethyl-1H-pyrazoles 5, 6, 7, 8, 11a-c, 12a-c and 13a c in good to excellent yields. In this way one of the, in general, inert methyl groups of 3,5-dimethyl-4-substituted-1H-pyrazoles is functionalized creating a new synthetic route to azoles containing a coordinating substituent.

CH2O + C7H9NO + C9H10O -> [CH4O +] C16H17NO2
A novel Mannich-type reaction between an aldehyde, an amine and a vinyl ether is catalysed by lanthanide triflates to afford a beta-amino ketone in good yield in aqueous media.

C21H18Cl2F3N3O7 -> [C10H6F3NO2 +] C11H12Cl2N2O5
A lipid-coated catalytic antibody was prepared by mixing aqueous solutions of antibody and synthetic glycolipids. The lipid-coated catalytic antibody is soluble in organic solvents and showed a remarkable reactivity for hydrolysis of lipophilic esters in buffer solution containing 20-80% DMSO (dimethyl sulfoxide). DMSO was added to solubilize the lipophilic esters and a native antibody was denatured in the same condition. Michaelis-Menten kinetics showed that the reduced reactivity of a native antibody i DMSO-buffer solutions is due to the largely deduced k(cat) value but not the small change of K-m, value.

C15H14O2 -> [C3H4 +] C12H10O2
Allyl carboxylates. carbamates and phenoxides may be cleaved or transacylated in the presence of palladium catalyst and either phenyltrihydrosilane or N-methyl-N-(trimethylsilyl)trifluoroacetamide. These reactions are totally compatible with the presence f Boc and, as far as phenyltrihydrosilane is concerned, Fmoc protections.

C9H16NO3* [+ NO3*] -> C9H16N2O6
Numerous gas/solid reactions of nitrogen dioxide with organic substrates are investigated preparatively and mechanistically. Gaseous NO2 reacts with crystalline stable free radicals (nitroxyls 1, verdazyl 6) by electron transfer. The nitrite ions formed a e irreversibly oxidized by NO2 via oxygen atom transfer. Solid cation nitrates are formed quantitatively. Thione bonds of thiohydantoins 8 are transformed to carbonyl bonds with formation of sulfur and NO presumably via nitrites as intermediates. Hydantoi 13 oxygenates at its free 5-methylene group via C-H abstraction and nitrite or it undergoes N-1 nitration via N-H abstraction depending on the conditions. Both reactions proceed quantitatively. 1,3-Oxazolidin-2-one (15) gives N-nitration and N-nitrosatio with the NO produced. Nonenolized crystalline barbituric acids 17 are quantitatively nitrated (C-N bond formation with radicals) at their methylene groups. 4-Hydroxybenzaldehyde (19) and vanilline (22) give quantitative aromatic nitration (C-N bond forma ion with arenes) without melting. All possible regioisomers are formed. Solid 9-methylanthracene (26) gives a quantitative yield of its 10-nitro derivative 27. Crystalline anthracene (28) and gaseous NO2 yield 3 primary products 29 (cis; trans) and the ne dimeric product 30 as well as the stable secondary products 31 and 32. The gas/solid tetranitration of tetraphenylethylene (33) is severely hindered by the water of reaction. However, a 95% yield of pure tetrakis(p-nitrophenyl)ethylene is obtained if the drying agent MgSO4 . 2H(2)O is admired and the product 34 extracted. The gas/solid procedures avoid solvents and fuming nitric acid. They give pure products without necessity for recrystallization in most cases and they avoid wastes. Atomic force microsco y (AFM) measurements on prominent faces of single crystals of 1a, 11a, 28, and 33 reveal phase rebuildings with well-directed long-range molecular transports. Nanoliquids were only present on (110) of 28. The characteristic AFM features are correlated wit known X-ray crystal structure data and compared with previous results. The shape of the features depends on the molecular packing in the crystal bulk and on the molecular shapes. Molecular interpretations of the AFM features are given.

C9H12 [+ O] -> C9H12O
Cerium(IV) ammonium nitrate (CAN)-catalyzed oxidation of alkyl aromatics with potassium bromate affords aldehydes, ketones acids or alcohols in high yields.

C16H23NO3 + C4H8O2 -> [C4H8O2 +] C16H23NO3
A chemo-enzymatic method for the preparation of homochiral esters of 14 secondary alcohols with 100% theoretical yields is described in one pot through two steps: the lipase-catalysed kinetic resolution followed by the Mitsunobu esterification of the free alcohol enantiomer in situ in the resolution mixture. Mathematical equations which link the enzymatic and chemical steps were derived, resulting in an enantioconvergent synthetic tool for the preparation of chiral intermediates.

C19H20N2O5 + C14H11BrO -> [BrH +] C33H30N2O6
Benzoin and furoin esters of N-carbobenzyloxyglycylphenylalanine were prepared and photolyzed under a variety of conditions. The photochemistry of peptide-derived benzoin esters is more efficient than that of furoin esters and is appropriate for the photo ytic initiation of biochemical processes. Methodology to assess the enantiomeric purity of the resulting free peptide was developed and used to monitor the protection-deprotection chemistry. Synthesis based on alkylation of the cesium salt of the peptide roved more effective than DCCI-mediated chemistry on stereochemical grounds.

C9H16N2 [+ C9H16N2] -> C18H32N4
2,2-Diethyl-4,5-dimethyl-2H-imidazoIe 1, formally a 1,4-diazadiene, does not produce (4 + 2) cycloadducts with various electronically-different dienophiles. In the presence of tri fluoroacetic acid, it tautomerizes to 2,2-diethyl-4-methyl-5-methylene-3-im dazoline 2 and forms a dimer, the structure of which was determined by X-ray crystallography.

C51H81N11O13S + C10H9I2NO3 -> [H2O +] C61H88I2N12O15S
A novel, highly specific iodolabelling reagent, glyoxytyltyramide 3, and its iodo-substituted derivatives are synthesized and used for the specific labelling of a linker modified Leu-enkephalin analogue.

C16H13BrO2 [+ H3] -> [BrO +] C16H16O
Reduction of the gem-disubstituted cyclopropane 1 with LiAlH4 yields different results under strictly anaerobic conditions and loosely anaerobic ones. Under strictly anaerobic conditions, (+)-1-bromo-2,2-diphenylcyclopropanecarbinol 2 is quantitatively re uced to 3 with complete racemization. These observations are explained by a radical chain mechanism. They open the way to reductions by LiAlH4 under mild conditions.

C9H10O3 [+ O] -> C9H10O4
The oxidation of methoxy aromatic aldehydes by the system O-2 / iPrCHO / metal catalyst proceeds in high yields of formates, almost without the formation of important quantities of carboxylic acids.

C9H10O3 + C4H10S3 -> [CH4O +] C12H16O2S3
A complete study has been made of the reaction of tris(methylthio)methyllithium with aromatic, heteroaromatic, and aliphatic esters. It is a one-pot reaction that despite its complexity, and depending on the reagent ratios, the reaction conditions, and th possible use of additional reagents (N-(methylthio)phthalimide or BuLi), can supply easily, in excellent and reproducible yields, the trimethyl alpha-keto trithioorthoesters 3 or, alternatively, the dimethyl a-keto dithioacetals 4. The reaction mechanism has been elucidated.

C23H28BrNO6 -> [BrH3 +] C23H25NO6
The aporphine alkaloid N-carbethoxydehydronorglaucine (1) was found to have promising in vitro antitumor activity, but poor water solubility. We report the synthesis of 1, the efficient hydrolysis of its urethane group and the further transformation into everal new dehydronorglaucine analogs.

C28H23ClN2O5S [+ O2] -> C28H23ClN2O7S
The cephalosporins 1-3 and Delta(2)-cephem 4 were oxidized in quantative yields to their sulfones with dimethyldioxirane. While in the case of 2-methylene-cephems (5,6) the exocyclic double bond oxidized simultaneously to the corresponding epoxide, the 3- inyl derivative (8) or 3-methylene-cephems (7) gave selectively the corresponding vinyl sulfone.

C11H16N2O2 [+ D] -> [H +] C11H15DN2O2
Regio- and chemi-selective, directed ortho-lithiation of 2-, 2,5- or 3,4-substituted pyridine N-oxides has been achieved with diisopropylamide and butyllithium. Polysubstituted pyridine N-oxides, azaxanthone, and an isomer of orelline have been synthesize by such methods.

C29H33NO4S3 -> [C5H3NS +] C24H30O4S2
Starting from thiopyridyl compounds bearing a radical stabilizing group in alpha-position to the thiopyridyl moiety, the thiopyridyl group can be easily removed upon reduction by line metal in acetic acid.

C5H5K + C8H7BrO2 -> [BrK +] C13H12O2
An alternative way for performing Suzuki reactions is presented. The necessary berate which is the actual nucleophile in these palladium catalyzed C-C-bond formations is prepared from 9-methoxy-9-borabicyclo(3.3.1)nonane (9-OMe-9-BBN) and a polar organome allic reagent RM, and not as usually from a borane and a base. This approach allows cross couplings of aryl halides with e.g. alkynyl-, methyl-, or TMSCH(2)-groups, which were beyond the scope of the conventional Suzuki reaction. The method is highly chem selective and turned out to be compatible with aldehyde-, amide-, ketone-, ester- and cyano functions as well as with basic nitrogen atoms in the substrates. It was applied to the synthesis of the acetylenic natural products junipal (9a) and eutypine meth l ether (10). Since B-11 NMR studies revealed that the 9-OMe-9-BBN only serves as a shuttle for delivering the RM reagent but remains unchanged during the course of the reaction, it has been possible to device the first Suzuki-type reaction sub-stoichiome ric in boron. This "catalytic" protocol was used to prepare compound 8 which is highly valuable for its chemoluminescence properties.

C10H12 [+ H2] -> C10H14
The synthesis of a variety of nonbridged optically active C-2- and C-1-symmetric titanocenes and zirconocenes is reported together with a detailed investigation of the ability of these complexes to effect the catalytic asymmetric hydrogenation of 2-phenyl 1-butene and 2-(alpha-naphthyl)-1-butene. The respective dihydro products are shown to be produced with enantiomeric excesses ranging from 4% to 69%. The absolute configuration of these 2-arylbutanes was noted to be sensitive to the three-dimensional char cteristics of the particular bicycle-fused ligand involved. For a series of verbenone-related metallocenes, an increase in the size of a substituent positioned alpha and syn to the metal center was found to be unfavorable for stereoinduction. This phenome on has been rationalized in transition state terms, with the alkene approaching laterally to engage in hydrogen atom transfer. The three-dimensional stereochemical model advanced in explanation of the observed catalytic selectivity underscores the develop ent of steric biases during olefin coordination to the reactive metal hydride intermediate.

C7H6O [+ H2] -> C7H8O
Diisobutylchloroalane (i-Bu(2)AlCl) exhibited remarkable chemoselectivity for the reduction of aldehydes and ketones in the presence of structurally different carbonyl compounds and other functional groups.

C15H14OS [+ D] -> [H +] C15H13DOS
Unexpectedly the cathodic activation of a,a-ethylenic sulfoxides in deuteriated polar solvents permitted quantitative conversion into monodeuteriated analogs on condition that electrolyses were stopped after a catalytic amount of electricity has passed th ough the electrolysis cell.

C4H5ClO [+ CH3] -> [Cl +] C5H8O
An improved procedure for the preparation of (E)-pent-3-en-2-one in high yields utilizing a Friedel-Crafts type alkylation of crotonyl chloride with trimethylaluminum is reported. Conversion of this enone into the corresponding enol silyl ether is also de cribed.

C10H9NO3 + C2H7NS -> [C2H6O +] C10H10N2O2S
Reaction of N-(sulfonyloxy)phthalimide derivatives 1, 2, with cystamine and homocystamine, respectively, affords bis((2,4-dioxo-1,2,3,4-tetra-hydroquinazolin-3- yl)alkyl)disulfanes 3, which could be reduced to 3-(mercaptoalkyl)quinazoline-2,4(1H,3H)-dione 5. (3-(2-Mercaptoethyl)quinazoline-2,4(1H,3H)-dione (5a) was also obtained in a one-pot reaction from 1 or 2 and cysteamine. 2-Ethoxy-4H-3,1 -benzoxazin-4-ones 4a-c were converted with cysteamine to 3-(mercaptoethyl)quinazoline-2,4-diones 5a-c by a new r ngtransformation reaction. 3- (2-Mercaptoethyl)quinazoline-2,4(1H,3H)dione (5a) and the corresponding disulfane 3a were evaluated for antiviral activity in vitro. Compounds 3a and 5a showed significant antiviral activity against some DNA- and RNA-viruses vaccinia-, herpes simplex virus type 1, influenza A virus) at concentrations that were nontoxic to the host cell cultures.

C3H7ClMg + C7H9N [+ CS] -> [ClHMg +] C11H15NS
The one-pot successive reactions of Grignard reagents with carbon disulfide and amines mediated by 1-trifluoromethylsulfonylbenzotriazole or triflic anhydride, provide an attractive and general route to thioamides. A wide variety of amines (primary alkyl, arylalkyl, secondary alkyl, cyclic amines, aniline, N-substituted anilines, heterocyclic amidines, amino alcohols, amino ethers, amino acetals, amino ketones, amino esters, amino amides (peptides), aminoalkenes, and diamines) and Grignards (primary alkyl, arylalkyl, aryl, secondary alkyl and tertiary alkyl) can be used, and thioamides are generally formed in good to moderate yields.

C8H14 [+ CH2O] -> C9H16O
Solvent free biphasic hydroformylation of various water-insoluble terminal olefins can be achieved in high yields and selectivities by using a water-soluble rhodium/triphenylphosphine trisulfonate catalyst and per(2,6-di-o-methyl)-beta-cyclodextrin as inv rse phase transfer catalyst. The catalytic activities were up to ten times higher than those observed without per(2,6-di-o-methyl)-beta-cyclodextrin.

C10H16O [+ H2] -> C10H18O
Asymmetric reduction of various enantiomerically pure ketones was carried out by using oxazaborolidine catalysts with a variety of achiral and chiral ligands. The efficiency of chiral 1, 2-amino alcohols as well as the effect of the stereogenic centers in the substrate on the catalytic asymmetric reduction were studied. It was found that the corresponding secondary alcohols were obtained with extremely high stereoselectivities with the proper choice of chiral ligands although a considerably large double as mmetric induction was observed in some cases.

C22H23NO4 [+ CH2] -> C23H25NO4
We report here a convenient method for the conversion of Fmoc amino acids to their N-methylated derivatives. Tile method involves reaction with formaldehyde and then reduction with triethylsilane (TES). Tile method is particularly attractive in that the a kylation and reduction are carried out in situ and the reaction sequence and purification of product can readily be carried out in one day. A further advantage is that tile method is not restricted to alpha-amino acids.

C9H12N2O4S + C5H4ClN5 -> [C4H4N2O2 +] C10H12ClN5O2S
A series of 2'-deoxy-4'-thioribo purine nucleosides was prepared by trans-N-deoxyribosylase- catalyzed reaction of 2'-deoxy-4'-thiouridine with a variety of purine bases. This synthetic procedure is an improvement over methods previously used to prepare p rine 4'-thio nucleosides. The compounds were tested against hepatitis B virus (HBV), human cytomegalovirus (HCMV), herpes simplex virus (HSV-1 and HSV-2), varicella tester virus (VZV), and human immunodeficiency virus (HIV-1). Cytotoxicity was determined n a number of cell lines. Several compounds were extremely potent against HBV and HCMV and had moderate to severe cytotoxicity in vitro. The lead compound from the series, 2-amino-6-(cyclopropylamino)purine 2'-deoxy-4'-thioriboside, was the most potent an selective agent against HCMV and HBV replication in vitro; however, this analogue was nephrotoxic when tested in vivo.

C28H48Si2TiR2+2 -> [C8H20Si2R*3 +] C20H28TiR*3+2
The (C(5)H5-nMe(n))(2)Ti(eta(2)-C-2(SiMe(3))(2)) (n = 0-5) (1A-1F) complexes were prepared by the reduction of corresponding titanocene dichlorides with magnesium in THF in the presence of bis(trimethylsilyl)acetylene (BTMSA). All of them were characteriz d by spectroscopic methods and (C(5)HMe(4))(2)Ti(eta(2)-C-2(SiMe(3))(2)) (1E) by the X-ray crystal analysis. The complexes decompose at temperatures in the range 100-200 degrees C. Those with n = 0-3 yield (mu-eta(5):eta(5)-fulvalene)(di-mu-hydrido)bis(et (5)-cyclopentadienyltitanium) (2A) and its methylated analogues (2B-2D) whereas BTMSA is released. The crystal structure of 2D showed that the hexamethylfulvalene ligand contains non-methylated carbon atoms in inner alternate positions. Complex 1E afforde a mixture of products. Among them only volatile isomers (eta(3):eta(4)-1,2-dimethyl-4,5-dimethylenecyclopentenyl)(eta(5)-tetramethylcyclopentenyl)titanium (2Ea) and (eta 3:eta 4-1,3-dimethyl-4, 5-dimethylenecyclopentenyl)(eta(5)- tetramethylcyclopentadie yl)titanium (2Eb) have been so far isolated as minor products. The C(5)Me(5) complex 1F yields quantitatively (eta(3):eta(4)-1,2,3-trimethyl-4,5- dimethylenecyclopentenyl)(pentamethylcyclopentadienyl)titanium (2F) and BTMSA is hydrogenated to a mixture of cis- and trans-bis(trimethylsilyl)ethene.

CCl2F2 + C2H2O4 [+ Na2] -> [C2H2ClFO2 +] FNa + ClNa + CO2
A chemical reaction has been discovered that mineralizes chlorofluorocarbons (CFCs) and enables the complete destruction of these environmentally hazardous species. The reaction products are easily handled solids, including recyclable alkali metal halides Under milder conditions, the same reaction causes partial defluorination of cyclic perfluoroalkanes to yield perfluoroarenes, which are valuable chemical intermediates. The vaporized substrates are passed over a packed bed of heated sodium oxalate; heati g at 270 degrees to 290 degrees C causes mineralization, whereas healing at 230 degrees C causes aromatization.

C8H18S [+ C8H16S] -> C16H34S2
Medium length aliphatic disulfides ave easily synthesized via the bromine-oxidation of thiols in the absence of solvent. Bromine can also oxidize long aliphatic and aromatic thiols to disulfides in solution. All yields are quantitative.

C13H16O3 [+ HN] -> C13H17NO3
Dimethoxyethane is an useful solvent for the Schmidt reaction of ketones and beta-ketoesters with sodium azide and methanesulfonic acid to afford amides and amidoesters. This solvent is an alternative to the unsafe chlorinated solvents normally used. A be a-diketone and several (4S)-N-(2-alkylacetoacetyl)-4-benzyloxazolidin-2-ones afford oxazoles under those conditions.

C6H6O [+ X] -> [H +] C6H5OX
Enzymatic oxidative polymerization of phenol has been carried out in an aqueous organic solvent using horseradish peroxidase as catalyst. The polymerization in a mixture of 1,4-dioxane and phosphate buffer (pH 7.0) (80:20 vol%) produced powdery polymeric aterials, which were partly soluble in DMF and DMSO. The molecular weight of the DMF-soluble part determined by GPC was 3.5x10(4). Polymerization conditions have been investigated with respect to the polymer yield, solubility, and molecular weight. The so vent composition enormously affected the polymerization. The polymer structure was estimated by IR and NMR spectroscopies and found to contain a mixture of phenylene and oxyphenylene units. From TG analysis, the polymer was found to possess high thermal s ability; 43 weight % of the polymer remained up to 1000 degrees C under nitrogen. DSC measurement showed no clear glass transition temperature or melting point.

C28H24O10 + C10H20N2O2Si2 -> [C8H20O3Si2 +] C30H24N2O9
Several beta-D-ribonucleosides were synthesized in high yields under mild conditions by N-glycosylations of methyl 2,3,5-tri-O-benzoyl-beta-D-ribofuranosyl carbonate (1) with trimethylsilylated nucleoside bases in acetonitrile using a catalytic amount of etal iodide such as SnI2, SbI3 or TeI4. A deprotection of N-6-benzoyl group of coupling product took place to a considerable extent when N-6-benzoyl-N-6,N-9-bis(trimethylsilyl)adenine was employed as a nucleoside base using SnI2 or SnCl2 as a catalyst whi e it was minimized when SbI3 or TeI4 was used. Further, the N-glycosylation of 1 with 7-trimethylsilyltheophylline in the presence of a catalytic amount of metal iodide was more effectively achieved in nitrile solvents other than acetonitrile.

C13H16BrN5O6S -> [C3H3BrO4S +] C10H13N5O2
Practical method to produce 2',3'-dideoxypurinenucleosides from 9-(2,5-di-O-acetyl-3-bromo-3-deoxy- beta-D-xylofuranosyl)purines (1) was developed. High ratio of 2',3 '-dideoxynucleoside to 3'-deoxyribonucleoside was obtained by Selecting the reaction con itions (solvent, pH and/or base), or changing 2'-acyloxy leaving group. The reaction mechanism was studied by deuteration experiments of 1a and 1-(3,5-di-O-acetyl-2-bromo-2-deoxy-beta-D-ribofuranosyl)thymine (12).

C11H14N6O [+ O] -> [HN +] C11H13N5O2
The deamination of eight kinds of racemic carbocyclic adenine nucleosides by adenosine deaminase under high-pressure (400 MPa) was examined and the result was compared with that obtained from the reaction under atmospheric pressure. The deamination of all carbocyclic nucleosides irrespective to their ring size of carbocycles was facilitated remarkably by high-pressure. The reaction of three and five membered carbocyclic pressure whereas the enantioselectivity of six membered carbocyclic nucleosides was sup ressed under high-pressure. However, the enantioselectivity of four membered nucleosides was low under both conditions.

C7H8O + C7H6BrNO2 -> [BrH +] C14H13NO3
`A simple, repid and efficient procedure for the synthesis of aromatic ethers via microwave irradiation without any organic solvent and inorganic carrier is reported.

C18H18N2O4S + C8H11N -> [CH4S +] C25H25N3O4
N,N'-di-(benzyloxycarbonyl)-S-methylisothiourea can be used in the mercury (II) promoted synthesis of bis-benzyloxycarbonyl protected guanidines.

C10H18O [+ H2] -> C10H20O
Diisopropoxytitanium(III) tetrahydroborate, ((PrO)-Pr-1)(2)TiBH4), generated in situ in dichloromethane from diisopropoxytitanium dichloride and benzyltriethylammonium borohydride in a 1:2 ratio selectively reduces aldehydes, ketones, acid chlorides, carb xylic acids, and N-Boc-protected amino acids to the corresponding alcohols in excellent yield under very mild reaction conditions (-78 to 25 degrees C).

C11H8O2 [+ O] -> C11H8O3
The epoxidation of vitamin K-3 was carried out using electrochemically generated hypohalogen acids HOX in organic solvent-water containing halide salts. The electroepoxidation in CH3CN-H2O-NaI system led to the formation of the epoxide in good yield.

C6H7O2P + C5H9ClO -> [ClH +] C11H15O3P
Functionalised phenylphosphinic acid derivatives have been synthesised by addition of bis(trimethylsilyl)phenylphosphonite 2 to a series of electrophiles.

C14H12 [+ CH2] -> C15H14
A convenient preparation of alpha-siloxymethyliron complex (7) was developed from commercially available s-trioxane and/or paraformaldehyde. For synthetic utility, iron methylidene complex (8) was generated in situ from the alpha-siloxymethyliron complex 7) and cyclopropanes (10) by treatment with alkenes.

C9H10N2O [+ C9H12CdN2O3] -> C18H22CdN4O4
The electrochemical oxidation of Co, Cu, Zn and Cd in non-aqueous (acetone) solution of cinnamic (CAH) and/or hippuric (HAH) acid hydrazides gave the corresponding 1:2 complexes in very good yields. The advantage of the method is discussed. When a neutral bidentate donor (1,10-phenanthroline) is present in solution, adducts with 1:1 ratio are formed. The compounds have been characterized on the basis of elemental analyses, electrical conductivity, magnetic and spectral studies. An octahedral structure is p oposed for the Co(II) and Cu(II) complexes. Also, the biological activity of the ligands and their metal complexes has been investigated.

C6H12O + C3H7N3O -> [H2N2O +] C9H17NO
The reactions of 1,2- and 1,3-hydroxy azides with aldehydes under acidic conditions were examined. A variety of Lewis acids were examined, of which BF3 . OEt(2) was found the most convenient. Trimethylsilyl ether derivatives of the alcohols could also be eacted using trimethylsilyl triflate as the promoter. Twenty-five examples that proceed in moderate to quantitative yields are reported.

C3H6O + C12H27LiSn -> [HLiO +] C15H32Sn
Primary allyl alcohols are converted into allyltributylstannanes in a one-pot operation. It entails (i) deprotonation with BuLi, (ii) sulfonylation with mesyl chloride, and (iii) nucleophilic substitution by LiSnBu(3). Conversions are quantitative with is lated yields ranging from 70 % to 100 %. If the starting allyl alcohol contains a stereogenic double bond its configuration is retained.

C19H13ClN2O2 [+ H2] -> C19H15ClN2O2
Inabenfide, 4-chloro-2-(alpha-hydroxybenzyl) isonicotinanilide (IBF) is a new plant growth regulator used for dwarfing rice plants to prevent lodging. This compound has one asymmetric carbon and catalytic reduction of the intermediate, 4-chloro-2-benzoyli onicotinananilide (IBF . KET) generates two isomers, S- and R-form IBFs in equimolar ratio. To avoid environment pollution, we undertook to develop selective S-form production by microbial reduction of IBF . KET. The productivity of S-form from IBF . KET as tested using 219 microbial strains. F-27 was selected for the highest productivity. The fermentation conditions were improved to increase the yield, and the composition of optimal medium thus selected was as follows;glucose 15%, pepton 1.5%, KH2PO4 0.5 , MgSO4 . 7 H2O 0.2%, NaCl 1.0%, and CoCl2 0.05% (pH 6.4). Strain F-27 was cultured with shaking at 27 degrees C for 4 days in the medium shown above, and then, emulsified IBF . KET was added to this culture at a concentration of 150 mg/ml. Further incuba ion for 11 more days resulted in conversion of IBF . KET to S-form IBF in yield more than 90% on a molar basis. IBF was extracted from a filter cake of culture broth with methanol, and concentration of the extract yielded S-form IBF in a crude crystalline form. Purified product was obtained in a yield of 84% by recrystallizing from methanol. The producing organism was identified as one of the fungi imperfecti, Agonomycetales sp., based on both morphological and physiological characterstics.

C11H16O2S + C6H10O3 -> C17H26O5S
The effect of tBuP4, a strong and cation-free base, on the yield and diastereoselectivity of additions of thus formed "naked" alpha-sulfonyl carbanions to achiral butyraldehyde and chiral isopropylidene-glyceraldehyde was studied. It has been found that w th tBuP4 a reasonable yield (similar to 55%) and a slightly better diastereoselectivity (72% of the anti diastreomer) are obtained with achiral and nonfunctionalized butyraldehyde while with isopropylideneglyceraldehyde the use of tBuP4 allowed us to grea ly increase the yields (up to 95-100%) and the diastereoselectivities (83-89% of a single diastereomer over the four possible diastereomers). It was also shown that the extra oxygen atom in the a-position plays a determinant role in this effect.

C8H8 [+ H2O] -> C8H10O
Hydration of aromatic alkenes (styrene, alpha-methylstyrene and E-stilbene) and alkynes (phenyl and diphenylacetylene) has been achieved by the reaction of the corresponding alkenes or alkynes on zinc borohydride combined with AIPO(4) in DME. Except in th case of alpha-methylstyrene, Zn(BH4)(2)/AIPO(4) provides a more efficient and selective catalytic system than the combination with SiO2 or Al2O3.

C26H22O4 -> [H2 +] C26H20O4
Irradiation of bis(p-anisyl)- or p-anisylphenyl-homonaphthoquinones 1a,b in the presence of Mg(ClO4)(2) results in the formation of indenonaphthoquinones 2a,b via intramolecular photoinduced electron-transfer.

C19H30BIrN6 + C2H3N -> C21H33BIrN7
Under appropriate conditions, the bis(ethylene) derivative Tp*Ir(C2H4)(2) (TP* = hydrotris(3,5-dimethyl-1-pyrazolyl)borate) reacts with MeCN to provide the Ir(III) complex Tp*Ir(CH=CH2)(C2H5)(NCMe) (1). In the presence of catalytic amounts of water, 1 und rgoes intramolecular coupling of the vinyl and acetonitrile ligands, with formation of a compound (2a) that contains a delocalized, five-membered iridapyrrole ring. This unusual cycloaddition reaction can be extended to other related alkenyl complexes of ridium.

C52H53Cl2MoN3P4 ->
The controlled potential electrolysis of a series of hydrazido(2-) complexes of molybdenum, (MoX(NNH2)(TR1)(PPh(3)))Y (TR1 = PhP(CH(2)CH(2)PPh(2))(2); 1, X = Y = Pr, 2, X = Y = Cl; 3, X = F, Y = BF4) in tetrahydrofuran (thf) at a mercury-pool electrode wi h 85% phosphoric acid as the proton source generates ammonia. The yield of ammonia is quantitative for 2. For 1 and 3 the yields are 0.32 and 0.24 mol of ammonia per mole of complex, respectively. These data are compared with yields of ammonia obtained fr m non-electrolysis methods. Copyright (C) 1996 Elsevier Science Ltd.

C14H15NO3 -> [C2O3 +] C12H15N
Benzazepine-based nitrones have been synthesized utilizing a modified Bischler-Napieralski reaction as the key step, These compounds are cyclic analogs of the radical nap phenyl t-butyl nitrone. Copyright (C) 1996 Elsevier Science Ltd

C9H11NO2 + C8H17Br -> [BrH +] C17H27NO2
Alkylation with n-octyl bromide of several substituted benzoic acids was performed under solvent-free phase transfer catalysis with excellent yields (greater than or equal to 95%) within very short times (2-7 min). Terephthalate octylation was raised from 20% to 92% under microwave activation when compared to conventional heating thanks to inirinsec effects of the radiation. Copyright (C) 1996 Elsevier Science Ltd

C8H13NO4 + C10H18O5 -> [C5H10O3 +] C13H21NO6
An improved method for the N-tert-butoxycarbonyl protection of the amino functionality of alpha-alkylated prolines and other sterically hindered alpha,alpha-disubstituted amino acids has been developed in which the lipophilic base tetramethylammonium hydr xide is used to solubilize the otherwise insoluble zwitterionic amino acid in acetonitrile, thereby obviating the need for an aqueous medium. Copyright (C) 1996 Elsevier Science Ltd

C60H59N4O13P [+ F] -> [H +] C60H58FN4O13P
Oxidation of H-phosphonate or H-phosphonothioate diesters with iodine in the presence of triethylamine trishydrofluoride furnished a rapid and quantitative formation of the corresponding phosphorofluoridate or phosphorofluoridothioate diesters. Copyright C) 1996 Elsevier Science Ltd

C7H5NS + C3H4Cl2O2 + C9H18OSi -> [C3H9ClSi +] C16H18ClNO3S
Various kinds of silyl enol ethers and ketene silyl acetals react with imidazole, thiazole and their benzo-derivatives in the presence of an alkyl chloroformate to give 2-substituted imidazolines and thiazolines in good yields.

C12H24O [+ CH2O] -> C13H26O2
Aldehydes are readily oxidized to methyl esters by a solution of methanol, pyridine, and trichloroisocyanuric acid in acetonitrile, acetone, or methylene chloride.

C19H29NO3 + C10H15NO -> [H2O +] C29H42N2O3
Steroidal 17 beta-amides 2, 4, 6 were synthesized from the 17 beta-carboxylic acids 1, 3, 5 and sterically hindered amine in 88-100% yields using 2,4,6-triisopropylbenzenesulfonyl chloride as a condensing reagent. This method was successfully applied to t e synthesis of sterically congested simple amide 8.

C23H25O4Ru2R2+2 [+ Cl] -> [C12H11 +] C11H14ClO4Ru2R2+2
Compounds of the general form Ru-2(CO)(4)(eta(5),eta(5)-C(5)H(4)LC(5)H(4)), where L = CH2-, (CH3)(2)C-, C2H4- and (CH3)(2)Si-, have been found to undergo photolysis in deuterobenzene or deuterotoluene to give 'twisted' ruthenium hydride complexes of the f rm (Ru(CO)(2))(Ru(CO)(2)H)(eta(5),eta(5):eta(1)-C(5)H(4)LC(5)H(3)). Reaction of these hydrides with chlorocarbons resulted in the formation of the corresponding chlorides which could be isolated and characterized by IR, H-1 and C-13 NMR, mass spectrometry and elemental analysis. In the particular case of Ru-2(CO)(4)(eta(5),eta(5)-C5H4(CH3)(2)SiC5H4) a secondary photochemical reaction occurs with formation of (Ru(CO)(2))(2)(mu-eta(5):eta(1)-C5H4)(mu-(CH3)(2)Si-(eta(5)-C5H4)) in which Ru-Ru and Cp-Si bonds ave been broken and new Ru-Cp and Ru-Si bonds formed. The molecular structure of (Ru(CO)(2))(RU(CO)(2)Cl)(eta(5),eta(5):eta(1)-C5H4CH2C5H3) was determined by X-ray crystallography:monoclinic, Cc, a = 27.636(5) Angstrom, b = 9.058(2) Angstrom, c = 14.545(5 Angstrom, beta = 120.85(3)degrees, V = 3126(2) Angstrom(3), Z = 8, R(F)= 2.29%.

C12H28OSn [+ C76H170Sn10] -> [O +] C40H90Sn5 + C48H108Sn6
Thermolysis of dibutyl(2-ethoxyethyl)stannane (4) in heptane at 150 degrees C quantitatively provides the perbutylated cyclopolystannanes (Bu(2)Sn)(5) (1) and (Bu(2)Sn)(6) (2). Trapping experiments reveal that this formal reductive-elimination process pro eeds in a step-wise manner, involving the generation of a trivalent tin. intermediate that then undergoes an. unprecedented beta-elimination reaction.

C6H8 [+ H2] -> C6H10
(Fv(Cr-2(CO)(6)) (Fv = fulvalene, eta(5):eta(5)-C10H8) exhibits the longest hithero known CpCr-CrCp bond and constitutes a catalyst for the radical dihydrogenation of conjugated dienes.

C8H7NO + C4H6O -> C12H13NO2
The (2+2)cycloaddition of phenyl isocyanate to 2,3-dihydrofuran was appreciably accelerated by compression to produce a beta-lactam ring; its apparent activation volume was estimated to be -28 ml mol(-1). Similar beta-lactams were obtained under high pres ure in the reaction of phenyl isocyanate with various vinyl ethers. Although the (2+2)cycloaddition of alkyl isocyanates to 2,3-dihydrofuran was also accelerated under high pressure to give beta-lactams with good yields; the reactions of alkyl isocyanates with ethyl vinyl ether were slow, even at high pressure.

C7H8O3PX + C12H17N [+ H] -> [X +] C19H26NO3P
Lewis acids or ultrasound catalyze the condensation of imines with Wang resin bound H-phosphonates to give high yields of the corresponding alpha-amino phosphonates or phosphonic acids. Copyright (C) 1996 Elsevier Science Ltd

C16H27O6P [+ Br] -> [HO +] C16H26BrO5P
O,O-Dialkyl alpha-hydroxybenzylphosphonates (1) can be easily converted in their corresponding alpha-bromo (2) or alpha-iodo (3) phosphonates. in quantitative yield, using (N) under bar,N'-carbonyldiimidazole (CDI) in the presence of allyl bromide or meth l iodide. Copyright (C) 1996 Elsevier Science Ltd

C19H19NO4 + C4H6O3 -> [CH4O +] C22H21NO6
N-Alkyl quaternary pavine salts were converted into N-alkyl tertiary pavines by refluxing ethanolamine, via a competitive N-dealkylation mechanism. The following N-dealkylation order was observed: benzyl > allyl > Me > Et > Pr-n greater than or equal to ( )Bu. Further study indicated that N-alkyl- and N-acylpavines could be obtained from N-methyl tertiary pavines in a one-pot reaction (acid anhydride/allyl bromide or alkyl halide, reflux). This finding provides an alternative method for preparing N-alkyl t rtiary pavines.

C56H81Co2O14P + C18H37O2P -> [C56H90O8P2 +] C18H28Co2O8
A range of diastereomeric alkynepentacarbonyldicobalt complexes containing the (R)-(+)-Glyphos ligand have been prepared in moderate to good yields under standard thermal conditions. Additionally, novel tertiary amine N-oxide mediated reactions have been eveloped which allow the synthesis of the same range of complexes at room temperature with good selectivity in consistently high yields. Optically pure (R)-(+)-Glyphos containing complexes have been obtained by preparative HPLC separation of the sets of d astereomeric compounds. Finally, the amine N-oxide techniques allow the rapid and clean preparation of alkynepentacarbonyltriphenylphosphinedicobalt complexes in good to high yields at room temperature.

C9H10O2 -> [CH2 +] C8H8O2
We describe some recent findings on similarities and differences in the cleavage of selected carboxylic esters from the viewpoint of reactivity effected by organotin oxides and hydroxides, under different modes of heating (oil bath or microwave irradiatio ). These studies complement earlier use of bis(tributyltin) oxide and provide a simple and efficient procedure of cleavage of carboxylic esters in apolar aprotic or without solvent, under mild conditions with readily available organotin reagents. Copyrigh (C) 1996 Elsevier Science Ltd

C8H7ClO2 + C6H5BrMg -> [BrClMg +] C14H12O2
The reactions of acyl tributylphosphonium ions in situ generated from acid chlorides and Bu(3)P in THF at -22 degrees C with primary alkyl and arylmagnesium halides have proved to be a convenient and simple procedure to prepare ketones from acid chloride n one-pot. Copyright (C) 1996 Elsevier Science Ltd

C15H32Sn + C5H4OS -> [C12H26Sn +] C8H10OS
Effective allylation of aldehydes, ketones and imines was accomplished by allylic tributyltins 1 in the presence of SnCl2 in an acetonitrile solution. In this reaction system, Sn(IV)-Sn(II) transmetallation must play a key role. generating the allylic tin II) reagents as a novel reacting species, Acetonitrile effectively promoted the transmetallation to give anti-adducts in the reaction with cinnamyltin 1c. whereas dichloromethane disturbed the transmetallation to produce syn-adducts. Copyright (C) 1996 El evier Science Ltd

C6H6O4 [+ H4] -> C6H10O4
The catalytic polymer film electrode which was coated with poly (N-(5-hydroxypentyl) pyrrole) film on carbon materials and incorporated palladium metal microparticles in films was prepared. By use of the electrode the electrocatalytic hydrogenation of ace ylenes in organic solvent-HCl buffer solution led to the efficient formation of ethanes in high current efficiencies.

C6H13BrO + C2H4OS -> [BrH +] C8H16O2S
Simple and high yielding methods for the synthesis and deprotection of S-trityl and S-acylhexanols and appropriately protected 2'-deoxynucleosides in solvent and dry media conditions are described which occur under mild conditions using microwave irradiat on.

C25H20O4 -> C25H20O4
The fluorescence spectra and photodimerization of polymethylene bis(2-naphthoate) (N - M(n) - N) in aqueous organic binary mixed solvents have been studied. Strong intramolecular excimer fluorescence was observed suggesting that hydrophobic interactions f rce polymethylene chains to self-coil. Photoirradiation of these solutions resulted in intramolecular dimerization of 2-naphthoate groups to give ring-closure products. The quantum yields for the photodimerization are significantly greater than those in o ganic solvents. This work provides an example of the application of hydrophobic interactions in expediting the formation of macrocyclic entities.

C9H9Cl [+ C9H9] -> [Cl +] C18H18
The quantitative synthesis and complete characterization of 1,2-bis(p-vinylphenyl)ethane (p,p-BVPE) and its meta-, para-mixed isomers are reported. These crosslinkers copolymerize randomly with p-methylstyrene, leading to random crosslink distributions. T e crosslinkers are prepared by Grignard coupling of (m,p)-vinylbenzyl chloride in tetrahydrofuran at low temperature to give the statistical mixture of m,m-, m,p-, and p,p-isomers in quantitative yield. Pure p-vinylbenzyl chloride is converted to pure p,p BVPE. p,p-BVPE has also been separated from the mixture of isomers. The isomers are characterized by elemental analysis, mass spectrometry, H-1-NMR, and C-13-NMR and by reversed-phase HPLC. (C) 1994 John Wiley & Sons, Inc.

C2H4O + C9H24N2Si2 [+ OX2] -> [C4H10Si2 +] C7H18N2O2X2
Well-defined poly(ethylene oxide)s with a primary amino group at one end and a hydroxyl group at the other terminus were synthesized with a new sila-protected amino functionality initiator, potassium N-(2-(2,2,5,5-tetramethyl-1-aza-2,5-disilacyclopentyl)- thyl)m?? ethyl amide (1b). 1b initiated an anionic polymerization of ethylene oxide (OE) to form a polymer (PEO) without any side reactions such as a cleavage reaction of protective group and a chain transfer reaction. The molecular weights of the PEO etermined from GPC and MALDI TOF-MS spectrometry agreed well with those from end group analysis using H-1 and C-13 NMR and TLC and also with the expected value from EO/initiator ratio. From these results, it was concluded that the polymers thus obtained ad a primary amino group at one end and a hydroxy group at the other end and can be regarded as hetrobifunctional PEO.

C9H10O2 -> [O +] C9H10O
Constant-current electrolysis (CCE) of a mixture of Bu3P, CH3SO3H, Bu4NBr, and a carboxylic acid (1) in CH2Cl2 using a one-compartment cell at room temperature gave the corresponding aldehyde (2) without any over-reduction products. The partial reduction was affected by the choice of cathode materials, depending on the structure of 1. Thus, by the CCE with two graphite plates as an anode and a cathode, aliphatic carboxylic acids were reduced smoothly into 2 in fair to good yields, regardless of the branc ing situation at their alpha-carbons. In the case of aromatic acids, a tin cathode was effective for the successful preparation of 2. Based on the results of cyclic voltammetry and P-31-NMR spectroscopy, acyl tributylphosphonium ions generated through a odic reaction are reduced to the alpha-hydroxylakyl tributylphosphonium ions at the cathode, which remain intact during the electroylsis and are decomposed to 2 and Bu3P only by the work-up under weakly basic conditions.

C16H34O + C8ClF15O -> [ClH +] C24H33F15O2
Structural analyses of fatty alcohols as acetate, trifluoroacetate and trimethylsilyl derivatives are frequently used in lipid biochemistry. Those derivatives produce molecular ions (m/z) < 400. Perfluorooctanoyl derivatives of fatty alcohols which can pr duce ions in the range of 600-700 (m/z) have never been studied before. We prepared perfluorooctanoyl derivatives of fatty alcohols by heating them with perfluorooctanoyl chloride for 15 min at 60 degrees C. Using low-power microwave irradiation (240 W), e can reduce the reaction time to only 2 min. The yields of the derivatives were quantitative by both microwave technique and conventional heating as evidenced by absence of starting material (fatty alcohols) in the HPTLC analysis. The mass spectral fragm ntation patterns of the derivatives obtained by microwave irradiation are identical to the derivatives prepared by conventional heating. We also prepared trimethylsilyl derivatives of fatty alcohols, a widely used derivative, in 1.5 min using microwave ir adiation (power 3, 240 W) where the conventional technique requires 20 min. We conclude that microwave irradiation can be employed for rapid preparation of perfluorooctanoyl and trimethylsilyl derivatives of fatty alcohols for gas chromatography-mass spec rometric analysis.

C33H46O2Si -> [C7H6 +] C26H40O2Si
An efficient and convenient method for the removal of benzyl ether protecting groups in the presence of other functionality has been developed. The method is sufficiently mild to allow the removal of trityl groups in the presence of benzyl ethers.

C17H17NO3S2 + C12H20F3NO4Si -> C29H37F3N2O7S2Si
Efficient methods for the Michael addition reactions of N-arylsulfonyl-3-phenylthiopiperidones (1) with both the protected amidoacrylates (4, 9) and the simple acrylates (12) have been developed. These reactions offer an efficient route to the 3-alkyl-sub tituted dihydropyridinones (3, 11), the dienophiles employed in the natural product synthesis.

C9H15NSi + C7H5N + C14H10O2 -> [C3H10O2Si +] C27H20N2
Some kinds of pyrroles, 1-pyrrolines, and 2H-pyrroles were synthesized from the N-silyl-1-azzaallyl anions and alpha-diketones by an one-pot reaction.

C17H19NO6 [+ C15H17NO5] -> C15H17NO5 + C17H19NO6
Efficient enzymatic resolutions at two stages of our route from benzene to amino(deoxy)inositols (rac-11a,b; 12a,b; 13a,b) and highly selective enzymatic asymmetrizations of meso-precursors (16d; 18a,b; 21b) on the way from tropilidene to diaminotetradeox heptitols provide enantiomerically pure (highly enriched) aminoglycoside building blocks.

C13H14O3 [+ O] -> C13H14O4
The treatment of 4,5-dialkyl-4-hydroxy-6-cyclopent-2-en-1-ones with H2O2 and KOH gave in high yields 2,3-epoxy-2,3-dialkyl-4-hydroxycyclopentanones. Furthermore, only one stereoisomer, characterized by trans relationship between the hydroxy group and the poxide was obtained. This behaviour can be explained considering that epoxidation occurs during a base catalyzed transposition of the starting cyclopentenone.

C21H21O4P -> [C17H10 +] C4H11O4P
New photochemically labile phosphate protecting group was developed. These phosphate esters have high molar extinction coefficient (epsilon340 = 34500 dm3 mol-1 cm-1) and rapidly release parent phosphates upon irradiation (>300 nm) with high quantum effic ency for disappearance (phi(dis) = 0.22 at 340 nm).

C8H16O3 [+ H2] -> C8H18O3
The reduction of the 2-keto acetals 1a and 1b by means of different microorganisms constitutes the biocatalytic access to optically active (46 to 100% ee) 2-hydroxy acetals, (S)-2a or (R)- and (S)-2b, representative compounds of a class of synthetically u eful chiral building blocks.

C27H30N2O9 -> [HN +] C27H29NO9
Reduction of 5-iminodaunomycin with dithionite in anaerobic methanol followed by lowering the pH to 3 and saturating with air led to deamination without glycosidic cleavage to yield 89% 5-deoxydaunomycin. An intermediate observed during the reaction is pr posed to be the hydroquinone tautomer, 8-acetyl-12-amino-10-((3-amino-2,3,6-trideoxy-alpha-lyxo-hexopyranosyl)oxy)-1-methoxy-7, 9,10,12-tetrahydro-6,8,11-trihydroxy-5(8H)-naphthacenone hydrochloride (1), which loses ammonia with a half-life of 49 min. Ana robic reduction of 5-deoxydaunomycin with bi(3,5,5-trimethyl-2-oxomorpholin-3-yl) (TM-3 dimer) in methanol buffered to an apparent pH of 8 yielded 26% recovered 5-deoxydaunomycin, 56% 5,7-dideoxydaunomycinone, and 18% 2-acetyl-11-hydroxy-7-methoxy-5,12-na hthacenedione (5) after 42 h and subsequent exposure to molecular oxygen. The reduction leads to relatively rapid formation of a long-lived transient proposed to be, 8-acetyl-10-((3-amino-2,3,6-trideoxy-a-lyxo-hexopyranosyl)oxy)-l-methoxy-7,9,10,12- tetra ydro-6,8,11-trihydroxy-5(8H)-naphthacenone (4). Exposure of 4 at its maximum concentration to molecular oxygen yielded 88% recovered 5-deoxydaunomycin and 12% 5. Tetrahydronaphthacenone 4 disappeared with a half-life of 2283 min in the absence of oxygen a d 16 min in air-saturated methanol. Mechanistic pathways to the products are proposed in Scheme II. Analysis of the apparent rate constants for disappearance of 4 indicates that 5-deoxydaunomycin undergoes glycosidic cleavage to its 7-deoxyaglycon 8000 ti es slower than daunomycin upon reduction to the hydroquinone state.

C9H10O -> [H2 +] C9H8O
A new selective and simple method for benzylic and allylic alcohols oxidation to aldehydes is reported. The oxidation is achieved with MnO2/bentonite1/microwave and MnO2/bentonite/ultrasound, both in dry medium.

C10H13NO [+ Cl] -> [H +] C10H12ClNO
Acetylhypobromite and tert-butylhypochlorite are the reagents of choice to synthesize new chiral N-bromo and N-chloro carbamates, amides, imides and oxazolidinones.

C19H21NO5S + C4H6O2 [+ C17H17NO4S] -> C19H21NO5S + C21H23NO6S
A practical lipase PS (Pseudomonas cepacia)-catalysed resolution of methyl threo-2-hydroxy-3-(4-methoxyphenyl)-3-(2-X-phenylthio)propionates 3, the (2S,3S)-enantiomers of which are important intermediates in the diltiazem synthesis, has been performed usi g acetone oxime, and isopropenyl or vinyl acetates as acylating reagents in organic solvents. The substituent X in compounds 3 does not have a clear effect on the enzymatic enantioselectivity, but the time needed for the resolution depends on X. The immob lization of the enzyme on Celite or Chromosorb in the presence of sucrose greatly enhances enzymatic activity. The immobilized enzyme is stable for reuse.

C11H10O [+ O] -> [H2 +] C11H8O2
A new catalytic method for the synthesis of vitamins of the K family is suggested. In this method 2-methyl-1-naphthol is oxidized by dioxygen in the presence of Mo-V-P heteropoly acids or their salts in a two-phase system (organic solvent + water) to 2-me hyl-1,4-naphthoquinone or vitamin K3, which is the precursor of all K family vitamins.

C12H16O2 -> [H2 +] C12H14O2
Anodic oxidation of cis-4-(p-methoxyphenyl)-2-methyl-3-buten-2-ol, 1, led to the formation of 7-methoxy-2,2-dimethyl-2H-benzopyran, 2 (Precocene I), via intramolecular cyclization, while oxidation of the trans-isomer, 3, under similar conditions produced rans-1-(p-methoxyphenyl)-1,4- butadiene, 4. These results are rationalized in terms of the selective absorption of the trans isomer on the electrode surface.

C14H11N [+ X2] -> C14H11NX2
The cationic homopolymerizations of N-vinylcarbazole 1-methoxy-1,3-butadiene, isobutyl vinyl ether, p-methoxystyrene, and cyclohexene oxide using three m,m'-dimethoxybenzyl esters as initiators have been investigated under both photochemical and dark cond tions. The comparison between the thermal polymerization and photopolymerization rates revealed that these initiators work mainly via a photocationic initiating mechanism. Only N-vinylcarbazole produced high molecular weight polymer; the other monomers pr duced only low molecular weight polymers (10(2)-10(3)). The order of the reactivity of these initiators is m,m'-dimethoxybenzyl 2,4,6-triisopropylbenzenesulfonate (DMB-TIBS) > m,m'-dimethoxybenzyl m-nitrobenzenesulfonate (DMB-NBS) > m,m'-dimethoxybenzyl t sylate (DMB-T). Changing initiator concentration and reaction temperature affected the polymerization yield but had little influence on the polymer molecular weight. Increasing the monomer nucleophilicity and the stability of the formed counterions enhanc d the polymerization rate and raised the product molecular weight. A photochemical initiation mechanism was suggested for these systems.

C7H5NO4 + C4H10O [+ C4H6] -> [O +] C15H21NO4
The liquid-phase esterification of 2,6-pyridinedicarboxylic acid (PA) with n-BuOH is efficiently catalyzed by heteropoly acid H3PW12O40 as a homogeneous catalyst and by its insoluble acidic Ce(III) salt, Ce0.87H0.4PW12O40, as a heterogeneous catalyst, yie ding 100% of PA dibutyl eater. The Ce(III) salt has a lower activity than H3PW12O40 but can be easily recovered and reused. Insoluble NH4+, K+ and Cs+ salts also exhibit moderate activities. The activity of the salts decreases in the series: Ce0.87H0.4PW1 O40 much greater than Cs2.5H0.5PW12O40 similar to Cs3PW12O40 similar to Cs2HPW12O40 similar to (NH4)(3)PW12O40 > K3PW12O40.

C8H8 [+ C8H12O2] -> C8H10O + C8H10O
Bis(mesityl)niobium (1) promotes hydroborations of alkenes by catecholborane but via an indirect mechanism.

C12H16O4S2 -> [O2S +] C12H16O2S
Vinyl sulfones are prepared in high yield by the treatment of 1,3-dithiolane tetraoxides with a catalytic amount of N,N-diisopropylethylamine in ethanol.

C8H17O3PS2 -> [CS +] C7H17O3PS
Diisopropyl (mercaptomethyl) phosphonate was easily prepared by the reduction of S-methyl phosphonodithioester with sodium borohydride, heated under reflux of acetonitrile. The phosphonate carbanion generated from the corresponding S-allyl sulfide underwe t a (3,2) sigmatropic shift, and led to diisopropyl (allyl mercapto methyl) phosphonate.

C12H16TiR2+2 + C8H18Si2 -> [CH4 +] C19H30Si2TiR2+2
Dimethyltitanocene reacts with diphenylacetylene to afford the vinyl complex resulting from insertion of the alkyne into one of the titanium-methyl bonds. Thermolysis of this vinyl complex results in extrusion of methane and formation of the titanacyclobu ene. Other alkynes similarly afford the corresponding titanacyclobutenes. In contrast, nitriles react with dimethyltitanocene to afford not azatitanacyclobutenes but rather diazatitanacyclohexadienes, incorporating 2 equiv of the nitrile.