In four mouthfuls of round-bottomed flasks of a 1L add compound 2 (40g), methanol (400mL), 7.7% Aqueous sodium carbonate (400mL), is heated to 70°C, after stirring reaction 2h, and TLC plate monitoring raw material Fundamental reaction is complete, and solution is divided into solid-liquid biphase, is extracted with ethyl acetate, collected organic layer, with anhydrous Sodium sulfate is dried, and vacuum obtains white solid, HPLC purity: 94.9% after being spin-dried for.White solid uses 40ml ethyl acetate and the mixed solvent recrystallization of 120ml normal hexane (1:3) again, Obtaining target compound is white solid 34.2g, yield 92%, HPLC purity: 99.7%.m.p.97-98￡ MS(m/z):236(M+H)+￡1H NMR(400MHz,CDCl3) |:2.43(s,3H,-CH3), 7.19-7.43 (m, 10H ,-CH=).
