N,N,N',N'-tetraalkyl-2,2'-dihydroxy-1,1'-binaphthyl-3,3'-dicarboxamides: Novel chiral auxiliaries for asymmetric Simmons-Smith cyclopropanation of allylic alcohols and for asymmetric diethylzinc addition to aldehydes

The newly introduced title compounds were found to be efficient chiral auxiliaries for the asymmetric Simmons-Smith cyclopropanation of allylic alcohols and for asymmetric addition of diethylzinc to aldehydes. For example, Simmons-Smith cyclopropanation of cinnamyl alcohol in the presence of N,N,N',N'-tetraethyl-2,2'-dihydroxy-1,1'-binaphthyl-3,3'-dicarboxamide (1b) proceeded with high enantioselectivity of 94% ee and addition of diethylzinc to benzaldehyde in the presence of N,N,N',N'-tetraisopropyl-2,2'-dihydroxy-1,1'-binaphthyl-3,3'-dicarboxamide (1e) proceeded with enantioselectivity of 99% ee. Although the reaction mechanism of these reactions is still nuclear, a monomeric seven-membered 2,2'-dihydroxy-1,1'-binaphthyl-3,3'-dicarboxamide (1)-Zn complex is considered to be an active species which catalyzes the above reactions, on the basis of NMR experiments.