反应详情

In tetrahydrofuran (20 ml), 2-methylbenzothiazole-5-carboxylic acid (0.97 g, 5.00 mmol) prepared in the Step 37-1-1 was dissolved, and triethylamine (0.66 g, 6.50 mmol) was added thereto. Under an ice cooling, ethyl chloroformate (0.71 g, 6.50 mmol) was added to the mixture. Under an ice cooling, the resulting mixture was stirred for 30 minutes. Under an ice cooling, sodium borohydride was suspended in ethanol (20 ml), and the above reaction solution was slowly added to the suspension. The mixture was allowed to warm to a room temperature and stirred for one hour. To the mixture, 3-N hydrochloric acid was added, and the resulting mixture was stirred for 10 minutes. Then, chloroform was added thereto, and the resulting mixture was neutralized with a saturated sodium bicarbonate solution. The chloroform layer was dried over anhydrous magnesium sulfate and then concentrated. The concentrate was purified by silica gel column chromatography (ethyl acetate:methanol=20:1 to 10:1) to give the title compound (0.52 g, 58%) as a light-yellow powder.

1. dissolutionwas dissolved
2. additionthe above reaction solution was slowly added to the suspension
3. stirringstirred for one hour
4. stirringthe resulting mixture was stirred for 10 minutes
5. dry with materialThe chloroform layer was dried over anhydrous magnesium sulfate
6. concentrationconcentrated
7. customThe concentrate was purified by silica gel column chromatography (ethyl acetate:methanol=20:1 to 10:1)