Diethyl chlorophosphate → Benzyl 7-(diethoxyphosphoryl)-3,7-diazabicyclo[4.1.0]heptane-3-carboxylate

Participants

Reaction Steps

NaBH4 (3.41 g, 90.3 mmol) was added portion wise to a solution of CuSO4.5H2O (10.73 g, 42.98 mmol) in methanol (200 mL) at 0° C. After 5 minutes, a solution of trans-benzyl 4-azido-3-(tosyloxy)piperidine-1-carboxylate and trans-benzyl 3-azido-4-(tosyloxy)piperidine-1-carboxylate (37 g, 85.95 mmol; mixed product from last step) in methanol (100 mL) was added at 0° C. After addition, additional NaBH4 (10.2 g, 270.6 mmol) was added in four portions over the course of 1 hour. After one hour at 0° C., the reaction mixture was filtered through a pad of celite and concentrated in vacuo. The residue obtained was dissolved in DCM (800 mL), washed with water (200 mL), saturated NH4Cl solution (200 mL), brine (200 mL), dried (sodium sulfate) and concentrated in vacuo. The residue obtained was dissolved in DCM (200 mL) and TEA (24.0 mL, 171.9 mmol) and diethyl phosphorochloridate (12.4 mL, 85.95 mmol) was added at 0° C. The reaction mixture was warmed to room temperature and stirred at room temperature for 30 minutes. Water (50 mL) was added. The organic layer was separated, washed with brine, dried (sodium sulfate) and concentrated in vacuo. The residue obtained was purified by flash chromatography on silica gel (ethyl acetate) to give benzyl 7-(diethoxyphosphoryl)-3,7-diazabicyclo[4.1.0]heptane-3-carboxylate (17.5 g, 55%) as an oil.

Provenance & Evidence