(s)-Tert-butyl 5-methyl-1,2,3-oxathiazolidine-3-carboxylate 2,2-dioxide → (R)-1-(2-tert-Butoxycarbonylamino-1-methyl-ethyl)-6-chloro-1H-pyrrolo[2,3-b]pyridine-2-carboxylic acid ethyl ester

Beteiligte Stoffe

Reaktionsschritte

A solution of 3.0 g (13.3 mmol) 6-chloro-1H-pyrrolo[2,3-b]pyridine-2-carboxylic acid ethyl ester in 70 ml N,N-dimethylformamide was cooled to 0 deg C. and 1.58 g (14.0 mmol) potassium tert-butoxide was added. After 30 min, 3.49 g (14.7 mmol) (S)-5-methyl-2,2-dioxo-[1,2,3]oxathiazolidine-3-carboxylic acid tert-butyl ester was added in one portion. The cooling bath was removed and after 1.5 h the reaction mixture was poured into 100 ml 10% aqueous citric acid. The layers were separated and the aqueous phase was extracted three times with ethyl acetate. The combined organic phases were washed four times with water, once with brine and then were dried over magnesium sulfate. After filtration the solvent was removed on a rotary evaporator and the residue was purified by flash-chromatography over silica gel (0.032–0.063 mm) with n-hexane:ethyl acetate (9:1, then 5:1) as eluant to afford the product as a yellow oil (98.0%).

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