Rhodium-catalyzed asymmetric hydroboration of γ,δ-unsaturated amide derivatives: δ-borylated amides.

gamma,delta-Unsaturated amides in which the alkene moiety bears an aryl or heteroaryl substituent undergo regioselective rhodium-catalyzed delta-borylation by pinacolborane to afford chiral secondary benzylic boronic esters. The results contrast the gamma-borylation of gamma, delta-unsaturated amides in which the disubstituted alkene moiety bears only alkyl substituents; the reversal in regiochemistry is coupled with a reversal in the sense of pi-facial selectivity.