Hydrochloric Acid → HCID 71008985, compound

Participants

Reaction Steps

A solution of (1S,2S)-rel-ethyl 2-((R)-2-(bis(tert-butoxycarbonyl)amino)-5,5-difluoro-4-methyl-5,6-dihydro-4H-1,3-oxazin-4-yl)cyclopropanecarboxylate (519 mg, 1.12 mmol) in ethanol (10 ml) and sodium hydroxide (2M; 2.24 ml, 4.49 mmol) was heated at 40° C. for 90 minutes. Thereafter hydrochloric acid (1N) was added dropwise under cooling with ice until a neutral pH was reached. For the workup, the solvent was removed at reduced pressure, the residue taken up in water and dichloromethane, and the mixture acidified by dropwise addition of hydrochloric acid (1N) under cooling with ice. The aqueous layer which was extracted 3 times with dichloromethane, then sodium chloride was added to the aqueous layer which was extracted again 3 times with dichloromethane. The combined organic layers were dried over sodium sulphate and concentrated at reduced pressure to give the crude (1S,2S)-rel-2-((R)-2-tert-butoxycarbonylamino-5,5-difluoro-4-methyl-5,6-dihydro-4H-[1,3]oxazin-4-yl)-cyclopropane-carboxylic acid (240 mg, 64% yield) which was used in the next step without further purification. MS (ISP): m/z=335.1 [M+H]+.

Provenance & Evidence