Iridium Complex-Catalyzed Highly Enantio- and Diastereoselective [2+2+2] Cycloaddition for the Synthesis of Axially Chiral Teraryl Compounds

Abstract

An asymmetric [2+2+2] cycloaddition of an α,ω-diyne, possessing ortho-substituted aryl groups on its terminus, and a monoalkyne with oxygen functionalities gave various axially chiral teraryl compounds. The coupling proceeded with extremely high enantio- (>99.5% ee) and diastereoselectivities (dl/meso = >95/5) when catalyzed by an iridium−chiral phosphine complex. As the products were readily transformed into diol compounds by deprotection without racemization, the present procedure provides access to a new chiral pool of diol compounds with C₂ symmetry.