4-(6-((8-CYCLOPENTYL-5-METHYL-7-OXO-7,8-DIHYDROPYRIDO(2,3-D)PYRIMIDIN-2-YL)AMINO)PYRIDIN-3-YL)PIPERAZINE-1-CARBOXYLIC ACID TERT-BUTYL ESTER
4-(6-((8-cyclopentyl-5-methyl-7-oxo-7,8-dihydropyrido(2,3-d)pyrimidin-2-yl)amino)pyridin-3-yl)piperazine-1-carboxylic acid tert-butyl ester