A mixture of 2-(2,6-dimethyl-4H-pyran-4-ylidene) malononitrile (1, 16.5 mg, 96 μmol) and aldehyde 2d (34.9 mg, 76.5 μmol) were dissolved in anhydrous EtOH (0.5 ml) at 65 C. Piperidine (1 μl) was added and the mixture was stirred at 80° C. for 6 hrs. The solvent was removed with a stream of N2 and the crude mixture was purified by reverse phase HPLC using water/acetonitrile 40-100% gradient. Yield: 8.1 mg (17.4%). LCMS: m/z 611 (M+H+), 623 (M+Na+). H-NMR (400 MHz, CD2Cl2): 7.45 (1H, d, J=16 Hz) 7.29 (2H, d, J=12 Hz) 7.17 (2H, d, J=8 Hz) 7.03-7.12 (2H, m) 6.69-6.79 (2H, m) 6.52-6.61 (2H, m) 4.76 (2H, brs) 3.89 (3H, s) 2.43 (3H, s) 1.52, (9H, s) 1.41 (9H, brs). C-NMR (400 MHz, CD2Cl2): 162.54, 159.01, 156.35, 152.56, 137.61, 137.21, 134.39, 133.06, 132.89, 128.82, 120.38, 118.39, 117.99, 115.03, 114.99, 107.37, 106.31, 80.21, 58.97, 55.49, 29.68, 28.00, 27.93, 19.75. The purified product (8.1 mg) was treated with a 4N HCl solution in dioxane (4 N, 0.65 ml) for 3 hrs. The mixture was diluted with hexanes, the precipitate centrifuged, re-suspended and washed with hexanes, then dried under vacuum. LCMS ESI+ m/z: 411 (M+H+). H-NMR (400 MHz, DMSO-D6) 7.22-7.28 (5H, m) 6.83-6.89 (2H, m) 6.65 (1H, d, J=16 Hz) 6.54 (1H, d, J=16 Hz) 5.54 91H, s) 5.32 (1H, s) 4.22-4.38 (2H, brs) 3.92 (3H, s) 2.39 (3H, s).
