To a stirred solution of 1-[3-(dimethylamino)propyl]-3-ethylcarbodiimide hydrochloride (0.121 g, 0.63 mmol), 1-hydroxybenzotriazole hydrate (0.087 g, 0.644 mmol), 4-dimethylaminopyridine (0.012 g, 0.098 mmol), pyridine (5 mL), and ammonia (0.5 M in 1,4-dioxane) (1.4 mL, 0.7 mmol) was added a solution of (2E)-3-{4-[cyclohexylidene(4-hydroxyphenyl)methyl]phenyl}-2-propenoic acid (8) (174 mg, 0.52 mmol) in pyridine (5 mL). The reaction mixture was stirred at room temperature under a nitrogen atmosphere for 4 d. The reaction mixture was concentrated and the crude product was partitioned between H2O and CH2Cl2. The organic phase was separated and washed with 1 N HCl (aq.) followed by brine. The organic phase was dried over MgSO4, filtered, and the filtrate was concentrated to give the crude product. The crude product was purified by flash chromatography on silica gel with CH2Cl2:MeOH (100:0 to 90:10) to give the desired product. The solid was dried under vacuum at 70° C. to give 29 mg (17%) of compound 12 as a white solid. 1H NMR (400 MHz, DMSO-d6): δ 1.54 (m, 6 H), 2.15 (m, 4 H), 6.53 (d, J=15.8 Hz, 1 H), 6.67 (d, J=8.5 Hz, 2 H), 6.85 (d, J=8.4 Hz, 2 H), 7.06 (m, 3 H), 7.36 (d, J=15.9 Hz, 1 H), 7.45 (d, J=8.2 Hz, 2 H), 7.50 (br s, 1 H), 9.33 (s, 1). The compound was silated prior to EI analysis. HRMS (EI) Calcd for C25H31 NO2Si: 405.2124 (M+). Found: 405.2126.
