Jean-Pierre Guemas

ADDITION OF ORGANOMETALLICS ON α,β-UNSATURATED THIOCARBONYL COMPOUNDS II. MICHAEL ADDITION OF LITHIUM ENOLATES ON THIOAMIDE AND DITHIOCARBAMATE VINYLOGS AND THIOAROYLFORMAMIDINE

Abstract α,β-Unsaturated thiocarbonyl compounds substituted by a secondary amino group in position β, such as thioamide vinylogs, dithiocarbamate vinylogs or thioaroylformamidines react with lithium enolates of esters, ketones or amides to give 1,4-addition compounds. In the presence of magnesium bromide 1,4-adducts undergo an intramolecular cyclization to give 2H-thiopyranones. Methylation of the 1,4-adducts is followed by a stereospecific elimination of the amine and leads to (1-Z)-1,3-dienic carbonyl compounds: with thioamide vinylogs, δ-methylthio-α,β,γ,δ-diethylenic ketones, esters and amides are obtained. Dithiocarbamate vinylogs give the α-ethylenic ketene dithioacetals, with a carbonyl function in δ-position. Substituted dihydrothiophenes and thiazolines are prepared by the reaction of ethyl α-chloro-α-lithiopropionate with aminopropenethione and thioaroylformamidine respectively.

Addition of organometallics to α,β-unsaturated thiocarbonyl compounds. III: Michael addition of active methylene compounds to thioamide and dithiocarbamate vinylogs

Abstract α,β-Unsaturated thiocarbonyl compounds substituted by a secondary amino group in position β, such as thioamide and dithiocarbamate vinylogs, react with sodium derivatives of active methylene compounds CH2XY to give 1,4-addition compounds. Methylation of the 1,4-adducts is followed by elimination of the amine and leads to conjugate thioethers and ketene dithioacetals with functional groups X and Y at the end of the chain. Cyclization and hydrolysis of the adduct afford 2H-thiopyran derivatives.

Addition Of Organometallics To α,β-Unsaturated Thiocarbonyl Compounds. Iv. Five-Membered Sulfur Heterocycles By 1,4-Addition Of The Carbenoid Ich,Mgcl

Abstract 2,3-Dihydrothiophenes, 2-arylthiophenes, 2-methylthio-3-arylthiophenes and 2-substituted thiazoles are prepared by 1,4-addition of iodomethylmagnesium chloride with β-aminopropenethione, methyl β-aminopropmedithioate and thioacylformamidines.