The lithium-halogen exchange-initiated intramolecular conjugate addition reactions of some model unsaturated acylphosphoranes have been examined. The effects of halide type, chain length, and acceptor substitution pattern on the feasibility of ring construction were studied. The lithium-bromine exchange reactions in two 2-bromoaryl acceptors were found to be too slow, relative to competing side reactions, to allow practical carbocycle ...
