To a solution of 1-methylspiro[chromeno[4,3-c]pyrazole-4,4′-piperidine] (211 mg, 0.830 mmol), 1H-benzimidazole-4-carboxylic acid (134 mg, 0.830 mmol) and triethylamine (346 μL, 2.50 mmol) in dichloromethane (2 mL) was added HATU (314 mg, 0.830 mmol) in one portion and the mixture was stirred for 12 hours. The reaction mixture was treated with 1M NaOH (1 mL) for 10 minutes. Dichloromethane (5 mL) was added. The two layers were separated and the aqueous layer was extracted with dichloromethane (2×5 mL). The organic layers were combined, washed with brine, dried over MgSO4, filtered and evaporated to yield a residue that was purified on silica using a gradient of 0.5-30% MeOH in dichloromethane to yield (1H-benzo[d]imidazol-4-yl)(1-methyl-1H-spiro[chromeno[4,3-c]pyrazole-4,4′-piperidine]-1′-yl)methanone. ESI-MS m/z calc. 399.5. found 400.5 (M+1)+. Retention time: 1.12 minutes (4 min run).
