Imidazole → (+/-)-(3R,4R)-benzyl 4-((tert-butyldimethylsilyl)oxy)-3-morpholinopiperidine-1-carboxylate

Participants

Reaction Steps

A mixture of benzyl 7-oxa-3-azabicyclo[4.1.0]heptane-3-carboxylate (prepared according to a published literature procedure: Fink, Brian, et al., WO 2005/066176, 700 mg, 3.00 mmol), morpholine (0.581 mL, 6.00 mmol), and lithium perchlorate (639 mg, 6.00 mmol) in acetonitrile (10 mL) was heated at 80° C. for 4 h. Solvent was evaporated and the crude intermediate was dissolved in dichloromethane (10 mL), imidazole (654 mg, 9.60 mmol) and tert-butyldimethylchlorosilane (1357 mg, 9.00 mmol) were added. The reaction mixture was stirred at room temperature overnight. The reaction was diluted with dichloromethane and washed with water and brine, dried over sodium sulfate, filtered, and concentrated. The crude product was purified by flash chromatography on silica gel using an automated ISCO system (220 g gold column, eluting with 5-30% ethyl acetate/hexanes) to give (+/−)-(3R,4R)-benzyl 4-((tert-butyldimethylsilyl)oxy)-3-morpholinopiperidine-1-carboxylate (Isomer A, 0.39 g) as a colorless oil and (+/−)-(3R,4R)-benzyl 3-((tert-butyldimethylsilyl)oxy)-4-morpholinopiperidine-1-carboxylate (Isomer B, 0.43 g) as a colorless oil. The structures were confirmed by NMR studies (1H-1D, 13C-1D, COSY, NOESY, dept-1H-13C-HSQC, 1H-13C-HMBC).

Provenance & Evidence