2-Diphenylphosphino-1,3-diphospholide anions

Article abstract of DOI:10.1016/S0022-328X(96)06291-2

The title compounds are easily obtained in four steps from 4,5-disubstituted 1,3-diphenyl-1,3-diphosphacyclopent-4-enes (1). Metallation of the P-CH₂-P unit of 1 followed by reaction with Ph₂PCl allows a diphenylphosphino group to be grafted onto 1 at the C₂ carbon. After removal of the remaining C₂H proton by a base, selective cleavage of the two P₁-Ph and P₃-Ph bonds by lithium in THF affords the corresponding 2-diphenylphosphino-1,3-diphospholide ions (5). In one case, the reaction of n-butyllithium with 1a leads to an opening of the five-membered ring via a nucleophilic attack at phosphorus. A bis-(phosphino)methanide ion (8) is thus obtained. Its chemistry has been investigated briefly.