Complementary regioselective cyclopropyl ring openings of 6- formyl-spirobicyclo[5.2]octane mediated by TMSC1 and TBAI

Article abstract of DOI:10.1016/S0040-4020(97)01019-3

Absolute control over the regioselectivity of trimethylsilyl halide-induced cyclopropane fragmentation of a spirofused cyclopropyl carboxaldehyde has been achieved by simply varying the reaction stoichiometry and the nature of the halide. Treatment of 6-formyl- spirobicyclo[5.2]octane with a large excess of TMSC1 gave 3-(1- chlorocyclohexyl)propanal (84% yield), whereas 2-(1- iodomethylcyclohexyl)ethanal (86% yield) was obtained using 10 equivalents each TMSC1 and n-Bu₄NI (TBAI). Use of only a moderate excess of TMSC1 or TMSC1 and TBAI gave the rearranged product 3-(1- cyclohexenyl)-propanal.