Continuous-flow copper hydride-catalyzed reduction of 2,1-benzoisoxazoles

N,O-Reduction of 2,1-benzoisoxazoles in continuous flow is reported using copper hydride catalysis for the formation of 2-aminobenzophenones, key intermediates and cost drivers in the synthesis of benzodiazepines. In particular, ligand selection and precise control over reaction conditions allowed selective N,O- over 1,2-reduction. Copper hydride catalysis was used for selective N,O-reduction of 2,1-benzoisoxazoles in continuous flow to access 2-aminobenzophenones, key intermediates and cost drivers in the synthesis of benzodiazepines.