A solution of 1′-(4-ethyl-3-methoxybenzoyl)spiro[benzo[b]pyrrolo[1,2-d][1,4]oxazine-4,4′-piperidine]-7-carboxylic acid (40 mg, 0.09 mmol), HATU (34 mg, 0.090 mmol), N,N-dimethylamine hydrochloride (7.3 mg, 0.090 mmol) and iPr2NEt (62 μL, 0.36 mmol) in DMF (1 mL) was stirred at room temperature overnight. The reaction mixture was filtered and purified by reverse phase LC-MS (10-99% CH3CN/H2O). Pure fractions were combined and evaporated to yield 1′-(4-ethyl-3-methoxybenzoyl)-N,N-dimethylspiro[benzo[b]pyrrolo[1,2-d][1,4]oxazine-4,4′-piperidine]-7-carboxamide. ESI-MS m/z calc. 473.6, found 474.5 (M+1)+; Retention time: 1.80 minutes (3 min run).
