Carboxyl transfer (O→C) on 3-Ph 2 PO propyl esters (9) gives an intermediate (10) from which the Ph 2 PO group may be removed by the Horner-Wittig reaction or by Ph 2 PO transfer (C→O) to give the title compounds. ... Org. React., 8 (1954), pp. 59–196 see pp 90-95 and table XVI 168.