Reactivity of lithium diphenylphosphonium diylides towards phosphorus electrophiles: Synthesis of α,β-unsaturated phosphorus compounds

Abstract

The study of the reactivity of non-stabilized, semi-stabilized and stabilized lithium diphenylphosphonium diylides 1– 4 towards Ph 2PCl, allowed the synthesis of various α,β-unsaturated phosphines 13– 14, via the intermediate formation of the corresponding functionalized monoylides 9– 10 and their in situ reaction with carbonyl compounds. In many cases, the reaction is Z-stereoselective and the created double bond can be di- or also trisubstituted. The precise 1H-NMR study of the phosphines 13a– d and the X-ray analysis of 13a ( Z isomer) allowed us to assign without ambiguity the stereochemistry of these compounds and to solve a 1H-NMR question. Contrary to reported results in the literature for 13a, we have shown that for the double bond of this phosphine, there is no exception to the general rule 3 J HH( trans)> 3 J HH( cis). The extension of this reactivity study to other phosphorus electrophiles such as Ph 2P(O)Cl, Ph 2P(S)Cl and (EtO) 2P(O)Cl allowed, as preliminary results, the E-stereoselective synthesis of styrylphosphine oxide and sulfide and diethyl styrylphosphonate.