Stability of regioisomeric sugar allyltins. Cleavage of the carbonoxygen bond under radical conditions

Secondary sugar allyltin derivatives [Sug–CH(SnBu3)–CHCH2] decompose at high temperature (140°C) with elimination of the tin moiety and opening of the sugar ring. The cis-dienoaldehydes thus formed react with Ph3PCH–CO2Me to afford the corresponding trienes, which spontaneously undergo stereoselective intramolecular [4+2] cycloaddition to optically pure, highly oxygenated bicyclo[4.3.0]nonene derivatives. Primary sugar allyltins [Sug–CHCHCH2–SnBu3] are thermally stable and do not decompose up to 170°C.