Increasing appendage diversity on 3,4-dihydro-3-oxo-2H-1,4-benzoxazines via Aphos-Pd(OAc)2-catalyzed Suzuki-Miyaura cross-coupling of aryl chlorides

A library of 32 members of 3,4-dihydro-3-oxo-2H-1,4-benzoxazines has been synthesized from two substituted 2-aminophenols via microwave-assisted one-pot regioselective annulation of 2-bromoalkanoates and subsequent Suzuki-Miyaura cross-coupling of the chloro-substituted scaffolds. The latter transformation was carried out using our Aphos-Pd(OAc)2 catalyst and the coupling of the aryl chlorides with arylboronic acids proceeded under mild reaction conditions at 60-80 °C in THF-H2O (10:1) in the presence of K3PO4·3H2O as the base to furnish the corresponding biaryl products in 80-98% yields.