Wittig-type reactions of 2-lithio-2-trimethylsilyl-1,3-dithian and related reactions

Abstract

2-Lithio-2-trimethylsilyl-1,3-dithian reacts with carbonyl compounds, R¹R²CO, to give alkylidenedithians, [graphic omitted]CR¹R²(after acidic hydrolysis), potentially valuable synthetic intermediates for C₁ homologation (e.g.→ R¹R²CH·CHO or R¹R²CH·CO₂H). In similar reactions, acetyl chloride appears to yield [graphic omitted](SiMe₃)·C(:CH₂)·OAc, styrene oxide gives [graphic omitted](SiMe₃)·CH₂·CH(OH)Ph, and cis-[PtCl₂(PPh₃)₂] gives cis-[PtCl{[graphic omitted]}(PPh₃)₂]. A homologous lithium reagent [graphic omitted]Li·CH₂·SiMe₃ with benzaldehyde furnishes [graphic omitted](CH₂·SiMe₃)·CH(OH)Ph.