Brønsted Acid-Catalyzed Atroposelective Coupling of Carboxylic Acids with Amines and Alcohols via Ynamide Mediation

Abstract

Carboxylic acids are readily available chemicals with broad applications in chemistry-related areas, and their coupling with amines and alcohols is a fundamental transformation in organic synthesis. However, the catalytic enantioselective coupling of carboxylic acids remains elusive, especially for the atroposelective reaction. Here we report a chiral Brønsted acid (CBA)-catalyzed atroposelective coupling of carboxylic acids with amines and alcohols using ynamides as coupling reagents. The novel enantiocontrol involving CBA-catalyzed ester addition enables the straightforward construction of axially chiral amides and planar-chiral esters with high enantioselectivities through atroposelective intermolecular amidation and intramolecular macrolactonization. Diverse medicinally relevant carboxylic acids can undergo direct late-stage modification by this method. Importantly, this reaction represents the first atroposelective coupling of carboxylic acids with amines, as well as the first chemocatalytic atroposelective coupling of carboxylic acids with alcohols. The resulting atropisomeric skeletons can be readily derivatized to chiral ligands and catalysts for asymmetric catalysis.