1-Piperazinecarboxylic acid, 4-[6-[[6-[(1E)-2-butoxyethenyl]-8-cyclopentyl-7,8-dihydro-5-methyl-7-oxopyrido[2,3-d]pyrimidin-2-yl]amino]-3-pyridinyl]-, 1,1-dimethylethyl ester [ 1941177-47-4 ]