2-(Ethylthio)-5-phenyl-7,8-dihydro-6H-cyclopenta[5,6]pyrido[2,3-d]pyrimidin-4-amine 2-(Ethylthio)-5-phenyl-7,8-dihydro-6H-cyclopenta[5,6]pyrido[2,3-d]pyrimidin-4-ylamine AIDS-144466 AIDS144466 NSC667080