The reactions of the phosphavinyl Grignard reagents, Z-[RPC(But)MgCl(OEt2)], R=cyclohexyl (Cy) or cyclopentyl (Cyp), with benzaldehyde have afforded the β-phosphaallylic alcohols, Z-RPC(But)C(H)(OH)Ph, after quenching with methanol. This methodology has been successfully applied to a series of other alkyl, aryl and functionalised aldehydes. The β-phosphaallylic alcohol, Z-CyPC(But)C(H)(OH)Ph, undergoes