4-Chloro-5-cyano-6-ethoxycarbonylmethylthio-2-methylpyrrolo/2.3-d/ pyrimidine AIDS-142833 AIDS142833 Ethyl ((4-chloro-5-cyano-2-methyl-7H-pyrrolo[2,3-d]pyrimidin-6-yl)thio)acetate NSC661173