The synthesis of alkenes via epi-phosphonium species: 2. A phosphorus Ramberg-Backlund reaction

Article abstract of DOI:10.1016/S0040-4020(98)00960-0

Stilbene may be synthesised with Z-selectivity from (α- bromobenzyl)benzyldiphenylphosphonium bromide by the action of amine bases. A series of stilbenes was synthesised by the action of N-bromosuccinimide and 2,2,6,6-tetramethylpiperidine directly upon dibenzyldiphenylphosphonium salts. The reaction, essentially a phosphonium analogue of the Ramberg- Backlund displays cis selectivity. The dibenzyldiphenylphosphonium salts were prepared by the one pot polymethylhydrosiloxane/titanium(IV) isopropoxide mediated reduction/alkylation of benzyldiphenylphosphine oxides.