反应详情

温度

0 °C

A suspension of 17.2 g of L-cysteine methyl ester hydrochloride and 20.5 g of N-(t-butoxycarbonyl)-L-serine in 300 ml of acetonitrile was treated at 0° C. with 10.1 g of 4-methylmorpholine. To the stirred solution was added dropwise at 10° C. within 30 minutes a solution of 20.6 g N,N-dicyclohexylcarbodiimide in 300 ml of acetonitrile. After stirring the reaction mixture for 3 hours at 0° C. the precipitate formed was filtered off, and the filtrate was evaporated in vacuo. The oily residue was dissolved in 200 ml of ethyl acetate and the solution washed consecutively with 0.5N hydrochloric acid, water, 5% aqueous sodium bicarbonate solution and brine. The organic layer was dried over sodium sulfate and evaporated in vacuo. The crude product was chromatographed on silica gel using ethyl acetate/n-hexane as eluent, and the so purified product was crystallized from diethyl ether/n-hexane to give N-[N-(t-butoxycarbonyl)-L-seryl]-L-cysteine methyl ester as white crystals with mp 72°-74° C.

1. customformed
2. filtrationwas filtered off
3. customthe filtrate was evaporated in vacuo
4. dissolutionThe oily residue was dissolved in 200 ml of ethyl acetate
5. washthe solution washed consecutively with 0.5N hydrochloric acid, water, 5% aqueous sodium bicarbonate solution and brine
6. dry with materialThe organic layer was dried over sodium sulfate
7. customevaporated in vacuo
8. customThe crude product was chromatographed on silica gel
9. customthe so purified product was crystallized from diethyl ether/n-hexane