tert-Butyl 4-(6-((6-(1-butoxyvinyl)-8-cyclopentyl-5-methyl-7-oxo-7,8-dihydropyrido[2,3-d]pyrimidin-2-yl)amino)pyridin-3-yl)piperazine-1-carboxylate

tert-Butyl 4-[6-[[6-(1-Butoxyethenyl)-8-cyclopentyl-5-methyl-7-oxo-7,8-dihydro-pyrido[2,3-d]pyrimidin-2-yl]amino]-pyridin-3-yl]-piperazine-1-carboxylate is an intermediate in the commercial development of palbociclib, a highly selective reversible inhibitor of cyclin-dependent kinases CDK 4/6, which is developed for the treatment of ER-positive and HER2-negative breast cancer.

4-[6-(6-bromo-8-cyclopentyl-5-methyl-7-oxo-7,8-dihydro-pyridino[2,3-d]pyridine-2-yl-amino)-pyridine-3-yl]-piperazine-1-carboxylic acid tert-butyl ester (9.8 g, 0.017 mol), DMF (140 ml), vinyl n-butyl ether (17 g,0.17 mol), K2CO3 (5.27 g, 0.041 mol), Pd2dba3 (1.6 g, 0.17 mmol) and DABCO (0.23 g, 2.04 mmol) were added to the reaction flask and then heated the mixture to 80 ~ 85 °C. Tert-butyl 4-(6-(8-cyclopentyl-5-Methyl-7-oxo-6-(1-propoxyvinyl)-7,8-dihydropyrido[2,3-d]pyriMidin-2-ylaMino)pyridin-3-yl)piperazine-1-carboxylate was obtained through purification.