N-Bis(methylthio)methylene Derivatives. VII. Syntheses and Reactions of Synthetic Equivalents of New 1,3-Dipolar Reagents Using N-Bis(methylthio)methylene Derivatives.
N-Cyano- or N-(p-toluenesulfonyl)-N'-(trimethylsilylmethyl)-S-methylisothioureas (3, 4), readily prepared by reactions of S, S'-dimethyl N-cyano- (1a)b and S, S'-dimethyl N-(p-toluenesulfonyl)- (1b) carbonimidodithioates with trimethylsilylmethylamine (2a), followed by N-alkylation, have been found to provide synthetic equivalents of iminoazomethine ylide. Treatment of these compounds with cesium fluoride in the presence of reactive hetero-dipolarophiles such as carbonyl compounds afforded 1, 3-dipolar cycloadducts, 4, 5-dihydro-2-iminooxazoles and 4, 5-dihydro-2-iminothiazoles, via the 1, 3-elimination of (methylthio)trimethylsilane.S-Methyl-S'-trimethylsilylmethyl N-cyano- (5a) and N-(p-toluene-sulfonyl)- (5b) carbonimidodithioates, also readily prepared from the corresponding 1a and 1b with (mercaptomethyl)trimethylsilane (2b), were used as new reagents for introducing a thioformaldehyde unit at a carbonyl carbon. Reactions of these compounds with aldehydes in the presence of cesium fluoride afforded thiiranes via the 1, 3-dipolar cycloaddition of iminothiocarbonyl ylide to the C=O double bond. Reactions of 5 with dimethyl fumarate and maleate in the presence of cesium fluoride in acetonitrile gave 1, 3-dipolar cycloadducts, dimethyl 2-(N-(p-toluenesulfonyl)imino)tetrahydrothiophene-3, 4-dicarboxylates.
Selective Conversion of 2-Mercaptoalkanols to Thiirans with Orthocarbonates
作者:Toshikazu Takata、Takeshi Endo
DOI:10.1246/bcsj.61.1818
日期:1988.5
give the corresponding thiirans in good yields in acid-catalyzed reactions in aproticsolvents. Effects of catalysts, solvents, and alkyl substituents of 1 were examined. Activity of the acid catalysts depended on their acidity (pKa), and the strong Lewis acid BF3·OEt2 also had high catalytic activity. Effects of solvents and alkyl substituents of 1 were little observed.
An Expeditious One-Pot Synthesis of Thiiranes from α-Halo Ketones in Solvent-Free Conditions Using Microwaves
作者:Lal Dhar Yadav、Ritu Kapoor
DOI:10.1055/s-2002-35222
日期:——
Thiiranes are obtained in excellent yields and with high diastereoselectivity upon microwave irradiation of a mixture of α-haloketones, O,O-diethyl hydrogen phosphorodithioate and alumina-supported sodium borohydride in solvent-free conditions.
Benzyne-induced ring opening reaction of thiiranes. Efficient synthesis of phenyl vinyl sulfides
作者:Juzo Nakayama、Satoshi Takeue、Masamatsu Hoshino
DOI:10.1016/s0040-4039(01)81261-2
日期:1984.1
A series of thiiranes react with benzyne to provide an efficient synthesis of phenyl vinyl sulfides. The reaction is stereospecific, thus producing cis-(phenylthio)-stilbene from cis-2,3-diphenylthiirane and trans-(phenylthio)stilbene from trans-2,3-diphenylthiirane.
Novel SN2 ring-opening reactions of 2- and 2,2-substituted thiiranes with thiols using Na+-exchanged X-type zeolite or triethylamine in methanol
作者:Hiroshi Takeuchi、Yasuhisa Nakajima
DOI:10.1039/a804879g
日期:——
the concentration and nucleophilicity of 2, the reactivity of 1 towards 2 and so on. This suggests that the reactions using Na+-zeolite X or Et3N proceed via a zwitterion or an ion-pairintermediate, respectively, by an SN2 attack on 1 of 2, having enhanced nucleophilicity due to the basic catalysts. The reactions using Na+-zeolite A-3 or H+-zeolite X in MeOH or benzene and that using H2SO4 in benzene