Borohydride → Benzyl ((2S,3S)-4-chloro-3-hydroxy-1-phenylbutan-2-yl)carbamate

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Reaction Conditions

Reaction Steps

To a solution of 75.0 g (0.226 mol) of N-benzyloxycarbonyl-L-phenylalanine chloromethyl ketone in amixture of 807 mL of methanol and 807 mL of tetrahydrofuranat -2° C., was added 13.17 g (0.348 mol, 1.54 equiv.) of solidsodium borohydride over one hundred minutes. The solventswere removed under reduced pressure at 40° C. and the residuedissolved in ethyl acetate (approx. 1 L). The solution waswashed sequentially with 1M potassium hydrogen sulfate,saturated sodium bicarbonate and then saturated sodiumchloride solution. After drying over anhydrous magnesiumsulfate and filtering, the solution was removed underreduced pressure. To the resulting oil was added hexane(approx. 1 L) and the mixture warmed to 60° C. with swirling.After cooling to room temperature, the solids werecollected and washed with 2 L of hexane. The resultingsolid was recrystallized from hot ethyl acetate and hexaneto afford 32.3 g (43% yield) of N-benzyloxycarbonyl-3(S)-amino-1-chloro-4-phenyl-2(S)-butanol, mp 150°-151° C. andM+Li+ =340.

Provenance & Evidence