Triethylamine → 4-Methyl-1,3-dioxol-2-one-5-ylmethyl(S)N-(t-Butoxycarbonyl)-3-hydroxy-alpha-methyltyrosinate

Beteiligte Stoffe

Reaktionsschritte

A solution of N-(t-butoxycarbonyl)-3-hydroxy-α-methyltyrosine (760 mg, 2.44 mmol), triethylamine (263 mg, 2.60 mmol) and 4-bromomethyl-5-methyl-1,3-dioxol-2-one (500 mg, 2.60 mmol) in dimethylformamide, 10 mL, is stirred at 60° C. for 3 hours under nitrogen. Most of the dimethylformamide is removed at 50°-60° C. and 0.1 mm and the residue is partitioned between saturated sodium bicarbonate solution, 10 mL, and ethyl acetate, 50 mL. The ethyl acetate extract is washed with water saturated with sodium sulfate, filtered and concentrated at 40°-45° C. and 15 mm. Flash chromatography of the residue over 40 g of silica gel 60 (230-400 mesh) with 3% methanol-97% chloroform as eluent affords 320 mg of the desired ester.

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