Copper(I)‐Catalyzed Asymmetric Vinylogous Aldol‐Type Reaction of Allylazaarenes

Abstract

A vinylogous aldol‐type reaction of allylazaarenes and aldehydes is disclosed that affords a series of chiral γ‐hydroxyl‐α,β‐unsaturated azaarenes in moderate to excellent yields with high to excellent regio‐ and enantioselectivities. With (R,RP)‐TANIAPHOS and (R,R)‐QUINOXP* as the ligand, the carbon‐carbon double bond in the products is generated in (E)‐form. With (R)‐DTBM‐SEGPHOS as the ligand, (Z)‐form carbon‐carbon double bond is formed in the major product. In this vinylogous reaction, aromatic, α,β‐unsaturated, and aliphatic aldehydes are competent substrates. Moreover, a variety of azaarenes, such as pyrimidine, pyridine, pyrazine, quinoline, quinoxaline, quinazoline, and benzo[d]imidazole are well‐tolerated. At last, the chiral vinylogous product is demonstrated as a suitable Michael acceptor towards CuI‐catalyzed nucleophilic addition with organomagnesium reagents.