Synthesis of Tricyclic Pyrazolo[1,5-a]pyrimidin-7(4H)-ones Featuring Regioselective Formation of the Core Structure

: Considering relatively undeveloped chemistry of ring-forming condensations of 1H-pyrazole-5- amines with cyclic versions of b-oxoesters, a novel tricyclic piperidine ring-fused pyrazolo[1,5-a]pyrimidin7(4H)-one scaffold was designed. The developed synthetic scheme features regioselective construction of the core tricyclic molecular scaffold and a remarkable case of convenient and high-yielding p-methoxybenzyl group removal from a secondary aliphatic amine that is suitable for parallel reaction arrays.