Copper- and Chiral Nitroxide-Catalyzed Oxidative Kinetic Resolution of Axially Chiral N-Arylpyrroles

Org Lett. 2022 Jul 22;24(28):5078-5083. doi: 10.1021/acs.orglett.2c01860. Epub 2022 Jul 7.

Abstract

A readily prepared C2-symmetric, α-hydrogen-substituted chiral hydroxylamine serves as a precatalyst to generate a chiral nitroxide in situ. This chiral nitroxide catalyst in combination with a copper co-catalyst functions as an oxidant for an unprecedented enantioselective oxidative kinetic resolution (OKR) of racemic axially chiral N-arylpyrrole alcohols using atmospheric oxygen as an environmentally friendly terminal oxidant. The OKR process provides the axially chiral N-arylpyrroles in er up to 3.5:96.5 and with s factors up to 24.