Unexpected one pot C (aryl)–N bond cleavage and Questiomycin A formation from the reduction reaction of 2-amino-6-nitrophenol derivatives.

2-Amino-6-nitrophenol derivatives 5A and 5B have been prepared from the bromonitro phenol derivative 4 using the Buchwald conditions. While attempting one pot reduction of nitro group and deprotection of phenolic benzyl group of the compounds 5A and 5B separately using Pd/C in methanol under H 2 atmosphere, an unexpected C(aryl)–N bond cleavage reaction had occurred which was followed by formation of a known compound Questiomycin A (2-amino-3 H -phenoxazin-3-one) 1 from both the compounds. In the present study, the danger of deamination of Buchwald products 5A and 5B under the conditions of catalytic hydrogenation and the simultaneous formation of phenoxazine 1 is disclosed. [ABSTRACT FROM AUTHOR]