Spiro[5.5]undecane sesquiterpene analogues. Bridging vinyl ether and vinyl acetal formation via intramolecular attack by an enol during bromination
Abstract
Bromination of 7,11-diphenylspiro[5.5]undecane-1,9-dione (2) in dichloromethane indicated the involvement of an unexpected proximity effect when the bridged acetal (4) and the bridged ether (5) were isolated.