Benzyl chloroformate → 1-Benzyloxycarbonylamino-2-phenylethylphosphonous acid

Participants

Reaction Steps

To a solution of (±)1-Amino-2-phenylethyl phosphonous acid (19) (12.95 g, 70 mmol) in dioxane (200 mL) and aqueous 1M NaOH (75 mL) at 0° C. was added dropwise benzyl chloroformate (20 mL). The pH of the solution during this addition was kept at 8-9 with the simultaneous addition of aqueous 1M NaOH (75 mL). The reaction mixture was stirred at room temperature for a further 16 hours and then was concentrated in vacuo to half volume. Washed with diethyl ether (2×75 mL) and then acidified to pH1 with the addition of concentrated aqueous hydrochloric acid. Extracted with ethyl acetate (3×80 mL) and the combined organic phases were washed with water (1×20 mL), dried over anhydrous MgSO4, filtered and evaporated in vacuo which gave after crystallization from ethyl acetate--light petroleum (±)N-CBZ-1-amino-2-phenylethyl phosphonous acid (20) (15.44 g) (mp 136-137° C.) (Baylis, E. K.; Campbell, C. D.; Dingwall, J. G., J. Chem. Soc., Perkin Trans. 1, 1984, 12, 2845, reports mp 137° C.).

Provenance & Evidence