Triethylamine → 6-(Hydroxymethyl)-2H-pyrido[3,2-b][1,4]thiazin-3(4H)-one

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Reaction Steps

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 (0.4.mL) was cooled to −10° C. and isobutyl chloroformate (0.339 mL) added. After 20 minutes the suspension was filtered through celite 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/e 195 ([M−H]−, 50%), 165(100%).

Provenance & Evidence