Phosphorus heterocycles. Part I. A conjugated cyclic methylenephosphorane

Abstract

The cyclic quaternary phosphonium salt 9,10-dihydro-9,9-diphenyl-9-phosphoniaphenanthrene bromide reacts with aqueous sodium hydroxide to give the corresponding cyclic methylenephosphorane as an incompletely characterised orange solid, the relative stability towards hydrolysis of which compared with its acyclic analogue, benzylidenetriphenylphosphorane, suggests some aromatic character in the phosphorus-containing ring.