Synthesis of ferrocenyl-substituted 1,3-dithiolanes via [3 + 2]-cycloadditions of ferrocenyl hetaryl thioketones with thiocarbonyl S-methanides.

摘要: Ferrocenyl hetaryl thioketones react smoothly with in situ generated thiocarbonyl S-methanides to give 1,3-dithiolanes. In the case of aromatic S-methanides, sterically more crowded 4,4,5,5-tetrasubstituted 1,3-dithiolanes (2-CH2 isomers) were formed as sole products. The reactions cycloaliphatic led mixtures 2-CH2 and 5-CH2 isomers major component being isomers. preferred formation latter products is explained by assumption that formal [3 + 2]-cycloadducts via a stepwise reaction mechanism stabilized 1,5-diradical key intermediate. complete change toward concerted 2]-cycloaddition was observed ylide ferrocenyl methyl thioketone.