Total Synthesis of (-)-Dendrobine via -Carbonyl Radical Cyclization

摘要

An efficient total synthesis of enantiomerically pure (-)-dendrobine (1) is accomplished based on an α-carbonyl radical cyclization rection. (S)-carvotanacetone (6) was converted to bicyclic acetal-enone 4 in five steps. CuI-mediated conjugate addition of 4-(trimethylsilyl)-3-butynylmagnesium chloride to 4 followed by treatment with TMSCl afforded trimethylsilyl enol ether 10.