SYNTHESIS AND CHARACTERIZATION OF SOME P-MENTHYLPHOSPHETANES, A NEW CLASS OF ELECTRON-RICH CHIRAL PHOSPHINES

1-Menthyl substituted phosphetane oxides 4 and 6 are prepared either by starting from (menthyl)PCl2 and an appropriate olefin, or by reacting (menthyl)MgCl with a 1-chlorophosphetane. Highly selective alkylation and halogenation reactions of the corresponding anions 4' afford alpha-substituted derivatives in diastereomerically pure form. Reductions of the phosphetane oxides with HSiCl3.Et3N proceed with retention of configuration about the phosphorus atom. The described procedure provide an access to a wide range of optically pure phosphines of known stereochemistry.