Tandem Amidation Catalysis in the Synthesis of Diazaphenoxazine Carboxamides of Pharmaceutical Interest

ABSTRACT Tandem amidation catalyzed synthesis of linear diazaphenoxazine carboxamide derivatives is reported. This was achieved by the reaction of 2-amino-3-hydroxypyridine and 2,3,5-trichloropyridine in aqueous basic medium which gave 3-chloro-1,9-diazaphenoxazine as white solid crystals. 3-Chloro-1,9-diazaphenoxazine was then subjected to Buchwald-Hartwig amidation coupling reaction with various amides namely formamide, phthalamide, 4- nitrobenzamide, benzamide and acetamide via water promoted catalyst preactivation protocol to afford the following, 3-amido derivatives of 1,9-diazaphenoxazine namely 3-formamido-1,9-diazaphenoxazine, 3- phthalamido-1,9-diazaphenoxazine, 3-(4-nitrobenamido)-1,9-diazaphenoxazine, 3-benzamido-1,9- diazaphenoxazine and 3-acetamido-1,9-diazaphenoxazine. The compounds were characterized using UV-visible, FTIR, 1 HNMR and 13CNMR spectroscopy.