Sodium borohydride → (4-Isopropylthiazol-2-yl)methanol

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Reaction Steps

Sodium borohydride (40.4 g, 1.07 mol) was added in portions over 5-6 min to a cooled (5° C.) solution of 4-(1-methylethyl)thiazole-2-carboxylic acid ethyl ester (Example 12; 193 g, 0.97 mol) in ethanol (1.0 L). The solution was allowed then to stir at room temperature overnight. Examination of the reaction by tlc showed that a minor amount of starting ester remained. A second portion of sodium borohydride (4.0 g, 107 mmol) was added and after the mixture was stirred at ambient temperature for 40 min, the volatiles were removed under reduced pressure. Water (1.5 L) was added and the mixture was adjusted to pH 5-6 using acetic acid, then was extracted with chloroform (3×500 mL). The organic extracts were washed with brine (500 mL), dried (MgSO4), filtered and concentrated in vacuo to give 125 g of the crude alcohol as an oil. The oil was slurried in diethyl ether/hexane (1:19, 500 mL) and after the mixture was cooled, the resulting solids were collected by filtration, were washed with hexane and dried to give 4-(1-methylethyl)thiazole-2-methanol (102.6 g, 67.4% yield).

Provenance & Evidence