Regio- and Diastereoselective Radical Hydroboration of N-Aryl Enamine Carboxylates for the Synthesis of anti-β-Amino Organoborons

Abstract

The regio- and diastereoselective hydroboration of N-aryl enamine carboxylates was achieved by dichloro-substituted N-heterocyclic carbene (NHC)-boryl radical to access the valuable anti-β-amino boron skeleton. Excellent diastereoselectivity (>95:5 dr) was obtained using dichloro-NHC–BH3 (boryl radical precursor) and the thiol catalyst. Broad substrate scope and good functional group tolerance were demonstrated. Further transformation of the product to amino alcohol exemplified the synthetic utility of this reaction.

Radical hydroboration for the synthesis of organoboron compounds

“…Also in 2023, our group reported the radical hydroboration of N -aryl enamine carboxylates 35 with dichloro-substituted NHC–borane 24 that allowed the synthesis of β-amino organoborons 36 (Scheme 10). 41 Exclusive β-regioselectivity and excellent diastereoselectivity (>95 : 5 dr) were achieved in this reaction.…”