N-bis(methylthio)methylene derivatives. VII. Syntheses and reactions of synthetic equivalents of new 1,3-dipolar reagents using N- bis(methylthio)methylene derivatives

Article abstract of DOI:10.1248/cpb.43.1425

N-Cyano- or N-(p-toluenesulfonyl)-N'-(trimethylsilylmethyl)-S- methylisothioureas (3,4), readily prepared by reactions of S,S'-dimethyl N- cyano- (1a) 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 heterodipolarophiles 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.

Full text of DOI:10.1248/cpb.43.1425

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