Sodium borohydride → (3R,4R)-benzyl 3-amino-4-(tosyloxy)piperidine-1-carboxylate

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Reaction Steps

To a 0° C. solution of CuSO4.5H2O (642 mg, 0.5 equiv) in methanol (30 mL), NaBH4 (200 mg, 1.05 equiv) was added. To the stirred black suspension was added a solution of trans-benzyl 4-azido-3-(tosyloxy)piperidine-1-carboxylate and trans-benzyl 3-azido-4-(tosyloxy)piperidine-1-carboxylate (2.21 g, 5.14 mmol) in methanol (20 mL). Additional NaBH4 (578 mg, 3 equiv) was added in four portions over the course of 1 h. The reaction mixture was filtered through a pad of Celite and concentrated. The residue was diluted with CH2Cl2 (70 mL), washed with water (15 mL), satd aq NH4Cl solution (2×10 mL), brine (15 mL), and dried over Na2SO4. Concentration afforded trans-benzyl 4-amino-3-(tosyloxy)piperidine-1-carboxylate and trans-benzyl 3-amino-4-(tosyloxy)piperidine-1-carboxylate (1.34 g, 64%). The product was used for the next step without further purification. MS ESI +ve m/z 405 (M+1).

Provenance & Evidence