42% |
With sodium formate;Pd(PPh3)4; In DMSO (100 ML)-CH3CN; water; |
Under nitrogen atmosphere, to a solution of this compound (4.00 g) in DMSO (100 mL)-CH3CN (100 mL) were added successively Pd(PPh3)4(485 mg) and sodium formate (4.76 g), and the mixture was stirred at 100 C. for 75 minutes. The solvent was evaporated under reduced pressure, and thereto was added water, and the mixture was extracted four times with Et2O, and dried over MgSO4. The solvent was evaporated under reduced pressure, and the residue was purified by silica gel column (hexane/ethyl acetate=10/1) to give ethyl 1,3-benzothiazole-6-carboxylate (1.21 g, 42%). 1H NMR (CDCl3, 400 MHz) delta 9.15 (s, 1H), 8.71 (dd, 1H, J=1.6, 0.5 Hz), 8.21 (dd, 1H, J=8.6, 1.6 Hz), 8.17 (dd, 1H, J=8.6, 0.5 Hz), 4.44 (q, 2H, J=7.1 Hz), 1.44 (t, 3H, J=7.1 Hz). |
42% |
With sodium formate;Pd(PPh3)4; In DMSO (100 ML)-CH3CN; water; |
Under nitrogen atmosphere, to a solution of this compound (4.00 g) in DMSO (100 mL)-CH3CN (100 mL) were added successively Pd(PPh3)4 (485 mg) and sodium formate (4.76 g), and the mixture was stirred at 100C for 75 minutes. The solvent was evaporated under reduced pressure, and thereto was added water, and the mixture was extracted four times with Et2O, and dried over MgSO4. The solvent was evaporated under reduced pressure, and the residue was purified by silica gel column (hexane/ethyl acetate = 10/1) to give ethyl 1,3-benzothiazole-6-carboxylate (1.21 g, 42 %). 1H NMR (CDCl3, 400MHz) delta 9.15 (s, 1H), 8.71 (dd, 1H, J=1.6, 0.5Hz), 8.21 (dd, 1H, J=8.6, 1.6Hz), 8.17 (dd, 1H, J=8.6, 0.5Hz), 4.44 (q, 2H, J=7.1Hz), 1.44 (t, 3H, J=7.1Hz). |