HCID 20285482, compound → HCID 20285471, compound

Participants

Reaction Steps

Crude N-(3-acetylthio-2-methylpropanoyl)-N-cyclopropyl-(dl)-alanine tert-butyl ester (60.2 g) was dissolved in a mixture of anisole (54 ml) and trifluoroacetic acid (96 ml). The resulting solution was stirred at room temperature for one hour. Trifluoroacetic acid was removed in vacuo and the residue was distributed between ethyl acetate and saturated sodium bicarbonate. The aqueous bicarbonate phase was separated and washed twice with ethyl acetate and then acidified to pH 4-5 with concentrated hydrocloric acid. The precipitated product was extracted into chloroform and washed twice with water. The organic phase was dried over magnesium sulfate, filtered and evaporated to give the crude acid as a thick yellow oil (22.9 g). The crude product was purified by HPLC, eluting with ethyl acetate/n-hexane/acetic acid (40:60:1), to give pure product as initially a pale yellow oil (9.6 g). The product was crystallized from ether/n-hexane to give colorless crystals, m.p. 83°-85° C.

Provenance & Evidence