1-azabicyclo [2,2,2] octan-3-one (3-quinuclidone) treated with triphenylethylphosphonium bromide in dimethylsulfoxide and sodium hydride gives pure 3-ethylidene-1 -azabicyclo [2,2,2] octane in high yield. Evidence for the existence of cis and trans isomers, whose structures were determined by study of long range coupling, is given by N.M.R. spectroscopy. A correlation with sarpaginelike indole alkaloids has been established and a simple rule for the determination of the configuration of the ethylidene side chain in such alkaloids is given.
UNIVERSITL LIBRE DE BRUXELLESFaculte' des Sciences SERVICE DE CHIMIE ORGANIQUE Directeur : Prof. R.H. MARTIN Communiqut a la Sociktk Chimique de Belgique le 24 mai 1965.