Activation of the C=P bond in phosphanylphosphaalkenes (C=P-P bond system) in the reaction with nucleophilic reagents: MeLi, nBuLi and tBuLi

Abstract

Three reactions of phosphanylphosphaalkene (1) with nucleophiles were performed to activate the diphosphorus monomer. We observed similar results in the reactions with MeLi and nBuLi, in which the P-P bond is cleavaged and triphosphorus systems [P(Me)2-CH(biph)-CH(biph)-P-(PtBu2)]− (1a′′) and [P(nBu)2-CH(biph)-CH(biph)-P-(PtBu2)]− (1b′′), respectively, are formed depending on the nucleophilic reagent (biph = biphenyl). In the case of tBuLi, the P-P bond remains intact; on the phosphorus atom, only one -tBu group is substituted, and as a result, [(biph)(H)C-P(tBu)-PtBu2]− (1c) is generated as a stable carbanion. We additionally investigated the effect of substitution in the phenyl ring in the course of these reactions by involving two other phosphanylphosphaalkenes (3 and 4). All initial reactions were conducted in tetrahydrofuran (THF) solution at ambient temperature.