A solution of 5-bromo-1,4-dihydro-benzo[d][1,3]oxazin-2-one (96 mg, 0.42 mmol) and 1-Boc-piperazine (100 mg, 0.54 mmol) in 2 ml toluene was added to a mixture of Pd2(dba)3 (8 mg, 0.009 mmol), BINAP (13 mg, 0.022 mmol), NaOt-Bu (121 mg, 1.26 mmol). With stirring, the solution was heated at 95° C.-100° C. for 4 hours and was allowed to cool to room temperature. The reaction mixture was filtered through celite and washed with ethyl acetate. The filtrate was washed with water and brine. After drying over MgSO4, the organic fraction was concentrated in vacuo and the resulting brown residue was purified by prep TLC to give 43 mg 4-(2-oxo-1,4-dihydro-2H-benzo[d][1,3]oxazin-5-yl)-piperazine-1-carboxylic acid tert-butyl ester as a yellow solid (31%).
