Palbociclib Impurity 91

2-Aminoethyl-amino Palbociclib is an impurity of Palbociclib (also known as compound number PD-0332991) (P139900), which 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. 2-Aminoethyl-amino Palbociclib can be used to prepare drugs for treating bacterial infections and breast cancer.