One-pot oxapropellane skeleton formation based on conjugate addition

Abstract

Reactions of five- and/or six-membered-ring ketones 1–5 possessing an ω-halogenoalkyl group and α′,β′-unsaturated ester function at the α-position with diorganocuprates afforded the oxapropellane compounds 20–24 in a one-pot, three-step procedure via 1,4-addition followed by intramolecular aldol condensation and O-alkylation. Similar reaction of α,α′-disubstituted cyclopentanone 6 afforded bicyclic products 28 and 29.