Synthesis, characterisation and reactivity of 2-functionalised vinylstannanes

The functionalised vinylstannanes of the type (E)/(Z)-Ph3SnCR′CHYRn and (E)/(Z)-Ph3SnC(YRn)CHR′ (YRn=NMe2, OEt, SMe, SEt; R′=Ph, Bu (n-butyl), Pe (n-pentyl), H) were prepared by non-catalysed or Pd-catalysed hydrostannylation reactions. Particular stereoisomers were isolated by means of preparative HPLC and fully characterised using 1H-, 13C- and 119Sn-NMR spectroscopy. The reactions of 2-functionalised vinylstannanes (E)/(Z)-Ph3SnCR′CHYRn with acetic and chloroacetic acid in CDCl3 proceeded by protodestannylation yielding Ph3SnOOCCH2X (X=H, Cl) and CHR′CHYRn. The results of kinetics measurements reveal that Lewis-basic substituents YRn facilitate the electrophilic cleavage of SnC bonds, and this effect increases with the basicity of the heteroatom Y, i.e. in the order S