SN2' SELECTIVE ALKYLATION OF ALLYLIC CHLORIDES AND MESYLATES WITH RZNX REAGENTS GENERATED FROM GRIGNARD-REAGENTS, ZINC-CHLORIDE, LITHIUM-CHLORIDE, AND CU(II)-SALTS

Treatment of RMgX (1 equiv. R = alkyl; X = Cl, Br) with ZnCl2 (1 equiv.) in a mixed solvent of THF and Et2O leads to a highly turbid white suspension. Addition of LiCl (1 approximately 2 equiv.) solubilizes the insoluble species to yield a colorless clear solution. Addition of a catalytic amount of a Cu(II)-salt followed by allylic halides or mesylates at 0-degrees-C approximately room temperature yielded S(N)2' products in high yields. Application for the synthesis of (E)-alkene dipeptide isosteres is also reported.