Organophosphorus Intermediates. IX. The Cleavage of α,ω-Bisdiphenylphosphinoalkanes With Lithium. A 13P N.M.R. Study

Abstract

The title phosphines, Ph2P(CH2).PPh2 (n = 2-5), react with lithium in tetrahydrofuran to give the corresponding 1, n-dilithio-1, n-di(phenylphosphines) directly with little or no intermediacy of the 1-lithio- 1-phenyl- n- diphenylphosphinoalkanes which can, however, be obtained by arylation of the diphosphides. Methylenebisdiphenylphosphine and 1,4-diphenyl-1,4-diphosphinane undergo exclusive phosphorus-alkyl carbon cleavage. The chemistry and 31P n.m.r. spectroscopy of the diphosphides are described and the mechanism of the cleavage reaction is discussed. Some cleavage reactions in liquid ammonia are described.