反应详情

A solution of 3-Oxo-3,4-dihydro-2H-pyrido[3,2-b][1,4]thiazine-6-carboxylic acid (500 mg) in THF (24 mL) with triethylamine (0.396 mL) was cooled to −10° C. and isobutyl chloroformate (0.339 ml) added. After 20 minutes the suspension was filtered through kieselguhr into an ice-cooled solution of sodium borohydride (272 mg) in water (8 mL), the mixture stirred 30 minutes and the pH reduced to 7 with dilute HCl. The solvent was evaporated and the residue triturated under water. The product was filtered and dried under vacuum to give a white solid (346 mg); MS (APCl−) m/z 195 ([M−H]−, 50%), 165(100%).

1. filtrationAfter 20 minutes the suspension was filtered through kieselguhr into an ice-
2. temperaturecooled solution of sodium borohydride (272 mg) in water (8 mL)
3. customThe solvent was evaporated
4. customthe residue triturated under water
5. filtrationThe product was filtered
6. customdried under vacuum