反应详情

A solution of the intermediate from Step C (0.4356 g, 1.446 mmol) and 1,1,3,3-tetramethoxypropane (1.572 mL, 9.54 mmol) in dry EtOH (11.39 mL) was heated by microwave irradiation at 160° C. for 6 h. Another 3.3 eq. 1,1,3,3-tetramethoxypropane was added and the reaction was subjected to microwave irradiation at 160° C. for 6 h. Another 3.3 eq 1,1,3,3-tetramethoxypropane was added and the reaction was subjected to microwave irradiation at 160° C. for 3 h. The reaction mixture was concentrated in vacuo and the resulting crude product was purified by silica gel chromatography using a hexanes/EtOAc gradient to afford the desired product, as a yellow solid. 1H NMR (500 MHz, CHCl3-d) δ 9.48 (dd, J=1.77, 0.4 Hz, 1H); 8.38 (dd, J=3.8, 1.8 Hz, 1H); 6.91 (dd, J=7.3, 3.8 Hz, 1H); 4.53 (q, J=7.1 Hz, 2H); 3.41-3.35 (m, 2H); 2.70-2.56 (m, 2H); 1.48 (t, J=7.1 Hz, 3H). m/z=337.9 (M+H).

1. customirradiation at 160° C. for 6 h
2. customirradiation at 160° C. for 3 h
3. concentrationThe reaction mixture was concentrated in vacuo
4. customthe resulting crude product was purified by silica gel chromatography