Triethylamine → N(2,2,4,4-tetramethyltetrahydrothiophene-3-yl)-t-butoxycarbonyl-D-serine amide

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Reaction Conditions

Reaction Steps

To a solution of 2.26 g. (11 mmole) of N-t-butoxycarbonyl-D-serine in 75 ml. of tetrahydrofuran is added 1.47 ml. (10 mmole) of triethylamine and the mixture cooled to -10° C. At this temperature is added 0.96 ml. (10 mmole) of ethyl chloroformate and stirring continued for 15 minutes. After cooling to -20° C., 1.6 g. (10 mmole) of dl-3-amino-2,2,4,4-tetramethyltetrahydrothiophene is added and the resulting mixture is allowed to warm to room temperature. Ethyl acetate is added and the mixture is washed twice with 50 ml. portions of 5% (by weight) aqueous citric acid, aqueous sodium bicarbonate (1×50 ml.) and saturated brine (1×50 ml.). The organic layer is dried (Na2SO4) and evaporated to dryness at reduced pressure to afford N(2,2,4,4-tetramethyltetrahydrothiophene-3-yl)-t-butoxycarbonyl-D-serine amide. This product is used without further purification in the next step. ##STR118##

Provenance & Evidence