Highly regioselective coupling reactions of allylic and propargylic alcohol derivatives with gamma,gamma-dialkoxyallylic zirconium species via Zr-to-Cu transmetalation

In the presence of CuCN, reaction of gamma,gamma-dialkoxyallylic zirconium species 4, generated in situ by treating triethyl orthoacrylate with zirconocene-butene complex, with allylic and propargylic phosphates proceeded at the alpha-position of 4 in a highly SN2'-selective manner to give the corresponding 5-alkenoates and 4,5-alkadienoates, respectively. In the present Cu(I)-mediated coupling reaction, the gamma,gamma-dialkoxyallylic zirconium species 4 serves as a synthetically useful homoenolate anion equivalent of propionate.