Asymmetric Iodolactonization Using a Trinuclear Zinc Complex Prepared from Bisaminoiminobinaphthol Ligand

Arai et al. have reported an asymmetric iodolactonization using a ligand having a BINOL group and two chiral aminoimino groups, such as (R)-3,3'-Bis[[[(1R,2R)-2-(isoindolin-2-yl)-1,2-diphenylethyl]imino]methyl]-1,1'-bi-2-naphthol (1). In this reaction, the equivalent-relation between 1 and metal salts is important to promote the reaction effectively. The reaction successfully proceeds in high yield and high enantioselectivity when using three equivalents of zinc acetate relative to the equivalent of 1. Furthermore, the X-ray analysis of the prepared zinc-complex coordinates with 1 has been determined and has clarified its structure forms a trinuclear zinc complex.