A mixture of benzaldehyde (290 μL, 2.87 mmol, 1.0 equ.), malononitrile (190 mg, 2.87 mmol, 1.0 equ.) and triethylamine (400 μL, 2.87 mmol, 1.0 equ.) in ethanol (10 mL) was stirred for 1 min, followed by the addition of 1,3-diphenyl-1H-pyrazol-5(4H)-one (678 mg, 2.87 mmol, 1 equ.). The precipitate was filtered off and washed with ethanol and hexanes, and re-crystallized from ethanol to give 6-amino-1,3,4-triphenyl-1,4-dihydropyrano[2,3-c]pyrazole-5-carbonitrile (330 mg, 0.845 mmol, 29%) as a white solid. 1H-NMR (400 MHz) CDCl3: 7.82-7.80 (d, 2H), 7.55-7.50 (m, 4H), 7.41-7.37 (t, 1H), 7.32-7.22 (m, 8H), 4.96 (s, 1H), 4.68 (s, 2H), 13C-NMR (100 MHz) CDCl3: 157.5, 147.7, 144.9, 142.6, 137.5, 132.2, 129.3, 128.8, 128.2, 128.2, 127.5, 127.4, 127.1, 126.9, 121.6, 118.9, 97.5, 64.8, 38.2; LC/MS-MS: 391.1→325.0 m/z; GS1 and GS2 at 30, DP=91, CE=33, CXP=22, tR=4.33 min.
