Parallel synthesis of acylsemicarbazide libraries: preparation of potent cyclin dependent kinase (cdk) inhibitors

Potent cyclin dependent kinase inhibitors were prepared using parallel synthesis methodology. Treating advanced intermediate 2 with a variety of hydrazides in DMSO at 80 °C for 30 min gave the desired acylsemicarbazides in good to excellent yield. Several compounds were active against cdk4/D1 and cdk2/E in the low nanomolar range. The SAR indicates a wide variety of substituents are tolerated at the acylsemicarbazide moiety.