Regio- and Diastereoselective Radical Hydroboration of N-Aryl Enamine Carboxylates for the Synthesis of Anti-Β-amino Organoborons.

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.