Rh-Catalyzed Conjugate Addition of o-Amino-arylboronates. Synthesis of Quinolines

Significance

Reported is a one-pot regiospecific Rh-catalyzed conjugate addition of o-amino­phenylboronic acids to α,β-unsaturated ketones to afford dihydroquinolines (A) which, without isolation, upon treatment with Pd/C palladium in refluxing toluene (in air) give quinolines in moderate to high yield. To compensate the complication of protodeboronation, 2-2.5 fold excess of o-aminophenylboronic acid was used. The substrate scope for the Michael acceptor is moderately studied; on the other hand, R^² was varied in only one example, and only three substituted boronic acids were studied.