Triphenylphosphine → (S)-2-tert-Butoxycarbonylamino-3-(2-chloro-6-nitro-phenoxy)-propionic acid benzyl ester

Participants

Reaction Conditions

Reaction Steps

Under an inert atmosphere, a solution of 6.5 g (25 mmol) of triphenylphosphine in 20 ml of tetrahydrofurane was treated with at 0° C. with 3.9 ml (25 mmol) of diethyl azodicarboxylate. Thereupon, 3.0 g (17 mmol) of 2-chloro-6-nitrophenol were added and the reaction mixture was stirred at 0° C. for 15 minutes. Finally, 4.93 g (17 mmol) of (S)-2-tert-butoxycarbonylamino-3-hydroxy-propionic acid benzyl ester were added and the reaction mixture was left to warm to room temperature. After stirring for 18 hours, for the working-up the solvent was evaporated under reduced pressure and the residue triturated in ether at 0° C. The precipitated triphenylphosphinoxide was filtered and washed with ether. The combined filtrates were evaporated to yield 12.8 g of the crude product as a brown-yellow oil. The crude product was purified by chromatography on silica gel using heptane and ethyl acetate as the eluent. There were obtained 3.9 g (50%) of the title compound as a yellow oil, [α]589=−5.96° (c=1.0% in MeOH), MS m/e (%): 468.1 (M+NH4+, 100).

Provenance & Evidence