Reactivity of lithium diphenylphosphonium diylides towards phosphorus electrophiles: Synthesis of alpha,beta-unsaturated phosphorus compounds

The study of the reactivity of non-stabilized, semi-stabilized and stabiliz ed lithium diphenylphosphonium diylides 1-4 towards Ph2PCl, allowed the syn thesis of various alpha,beta -unsaturated phosphines 13-14, via the interme diate formation of the corresponding functionalized monoylides 9-10 and the ir in situ reaction with carbonyl compounds. In many cases, the reaction is Z-stereoselective and the created double bond can be di- or also trisubsti tuted. The precise H-1-NMR study of the phosphines 13a-d and the X-ray anal ysis of 13a (Z isomer) allowed us to assign without ambiguity the stereoche mistry of these compounds and to solve a H-1-NMR question. Contrary to repo rted results in the literature for 13a, we have shown that for the double b ond of this phosphine, there is no exception to the general rule (3)J(HH)(t rans) > (3)J(HH)(cis). The extension of this reactivity study to other phos phorus electrophiles such as Ph2P(O)Cl, Ph2P(S)Cl and (EtO)(2)P(O)Cl allowe d, as preliminary results, the E-stereoselective synthesis of styrylphosphi ne oxide and sulfide and diethyl styrylphosphonate. (C) 2001 Elsevier Scien ce B.V. All rights reserved.