Zn(II)-Catalyzed Addition of Aromatic/Heteroaromatic C(sp2)-H to Azoalkenes: A Polarity-Reversed Arylation of Carbonyl Compounds

Org Lett. 2019 Jun 7;21(11):4388-4391. doi: 10.1021/acs.orglett.9b01628. Epub 2019 May 22.

Abstract

An umpolung α-(hetero)arylation strategy that involves the Michael-type reaction between electron-rich (hetero)aromatic substrates and azoalkenes is developed. The reaction proceeds under very mild conditions at room temperature and in the presence of inexpensive, nontoxic ZnCl2 catalyst to provide access to otherwise inaccessible hydrazone structures. Subsequent hydrolysis of these latter to ketones as well as other valuable synthetic transformations to a variety of heterocyclic scaffolds demonstrate the usefulness of this protocol.