2,4-dichloro-7H-Pyrrolo[2,3-d]pyriMidine-7-carboxylic acid 1,1-diMethylethyl ester; tert-butyl 2,4-dichloro-7H-pyrrolo[2,3-d]pyrimidine-7-carboxylate; 2,4-Dichloro-7H-pyrrolo[2,3-d]pyrimidine-7-carboxylic acid tert-butyl ester;