Lithium borohydride → 5-Amino-1,2-benzisothiazole-3-ethanol

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Reaction Conditions

Reaction Steps

A mixture of ethyl 5-amino-1,2-benzisothiazole-3-acetate (3.14 g, 0.0133 mol) in tetrahydrofuran is cooled to -8° C., treated dropwise with a 2 M solution of lithium borohydride in tetrahydrofuran (5.00 mL, 0.0100 mol), stirred at room temperature for 3.5 hours, cooled to -5° C., treated with additional lithium borohydride solution (4.20 mL, 0.0084 mol), stirred at room temperature overnight, cooled to 0° C., quenched sequentially with water (5.00 mL) and 10% hydrochloric acid (10.0 mL), stirred at room temperature for one hour, neutralized with saturated sodium hydrogen carbonate solution (10.0 mL), and concentrated in vacuo to obtain a residue. The residue is diluted with a 5% methanol in methylene chloride solution. The resultant mixture is diluted with water, brine and methylene chloride. The phases are separated and the organic phase is concentrated in vacuo to obtain an orange gum. The gum is crystallized from methanol to give the title product as a tan solid which is identified by NMR spectral analysis.

Provenance & Evidence