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

Participants

Reaction Steps

To a cooled (0° C., ice/water bath) solution of CuSO4.5H2O (642 mg, 0.5 equiv) in methanol (30 mL) was added slowly NaBH4 (200 mg, 1.05 equiv). To the stirred black suspension was added a solution of (3R,4R)-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 introduced into the reaction in four portions over the course of 1 h. LC-MS showed the reaction was complete. 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) and brine (15 mL), and dried over Na2SO4. Concentration afforded (3R,4R)-benzyl 3-amino-4-(tosyloxy)piperidine-1-carboxylate (1.34 g, 64%). LC-MS (3 min) tR=1.26 min., m/z 405 (M+1). The product was used for the next step without further purification.

Provenance & Evidence