Cu(I)-catalysed enantioselective chlorine atom transfer with vinyl radicals

Abstract

Enantioselective intermolecular atom transfer reactions of vinyl radicals have hitherto remained elusive mainly due to their inherently high instability and reactivity which significantly compromises the stereodiscriminating substrate-catalyst interactions. Herein, we describe Cu(I)-catalyzed enantioselective chlorine atom transfer with vinyl radicals using tailormade tridentate anionic N,N,N-ligands featuring bulky peripheral substituents. This reaction readily accommodates (hetero)aryl and alkyl sulfonyl chlorides as radical precursors and more importantly, a large panel of 2-aminoaryl and 2-oxyaryl alkynes as substrates, providing highly transformable axially chiral vinyl chlorides in moderate to good yield with excellent enantioselectivity. The reaction can be easily scaled up to gram scales and straightforward manipulations of the thus obtained vinyl halides lead to axially chiral thiourea, pyridyl carboxamide, and quinolyl sulfonamide compounds, which are promising chiral reagents for asymmetric catalysis. Both experimental and theoretical mechanistic studies supported the proposed chlorine atom transfer reaction mechanism.