Hydrochloric Acid → 1-(Diphenylmethyl)azetidin-3-one

Participants

Reaction Conditions

Reaction Steps

Oxalyl chloride (145.2 g, 1.121 mol) was added to dichloromethane (3.75 liters) and the resulting solution was cooled to −78° C. Dimethyl sulfoxide (179.1 g, 2.269 mol) was then added over a duration of 20 minutes while maintaining internal temperature of the reaction below −70° C. during addition. 1-Benzhydrylazetidin-3-ol (250.0 g, 1.045 mol) was then added as a solution in dichloromethane (1.25 liter) to the −78° C. solution of DMSO/oxalyl chloride over a duration of 40 minutes (note—internal temperature maintained below −70° C. during addition). The solution was stirred for 1 hour at −78° C. followed by the addition of triethylamine (427.1 g, 4.179 mol) over 30 minutes (maintained internal temperature below −70° C. during addition). The reaction mixture was then allowed to come to room temperature slowly and stir for 20 hours. 1.0 M hydrochloric acid (3.2 liters, 3.2 mol) was added to the crude reaction solution over 30 minutes, followed by stirring for 10 minutes at room temperature. The heavy dichloromethane layer (clear yellow in color) was then separated and discarded. The remaining acidic aqueous phase (clear, colorless) was treated with 50% sodium hydroxide (150 ml, 2.1 mol) with stirring over a 30-minute period. The final aqueous solution had a pH=9. At this pH, the desired product precipitated from solution as a colorless solid. The pH=9 solution was stirred for 30 minutes and then the precipitated product was collected by filtration. The collected solid was washed with 1.0 liter of water and then air dried for 36 hr to give 1-benzhydrylazetidin-3-one (184.1 g, 74%) as an off-white solid: +ESI MS (M+1 of hydrated ketone) 256.3; 1H NMR (400 MHz, CD2Cl2) δ 7.47-7.49 (m, 4H), 7.27-7.30 (m, 4H), 7.18-7.22 (m, 2H), 4.60 (s, 1H), 3.97 (s, 4H).

Provenance & Evidence