6-broMo-8-cyclopentyl-5-Methyl-2-(5-(piperazin-1-yl)pyridin-2-ylaMino)pyrido[2,3-d]pyriMidin-7(8H)-one

6-Desacetyl-6-Bromo Palbociclib is an impurity of Palbociclib (P139900),(also known as compound number PD-0332991) is an experimental drug for the treatment of breast cancer being developed by Pfizer. It is a selective inhibitor of the cyclin-dependent kinases CDK4 and CDK6.Also, it is derived from 6-Bromo-2-chloro-8-cyclopentyl-5-methylpyrido-[2,3-d]pyrimidin-7(8H)-one (B682195), which is used to prepare pyridino[2,3-d]pyrimidin-7(8H)-one derivatives as CDK4 and/or CDK6 inhibitors useful in the treatment of diseases.