The regioisomers (2a,b) of the piperidinering of febrifugine (1a) and isofebrifugine (1b) were synthesized from 4-allyl-3-piperidone (5). Reduction of 5 afforded a mixture of the trans and cis alcohols (6a,b) without diastereoselectivity; this result differentiated it from the reduction of 2-allyl-3-piperidone (14). The antimalarial activity of 2a,b and related compounds was tested.
The Pyrazolo[1,5-a]pyrimidine derivatives represented by formula I and their pharmaceutically acceptable salts exhibit excellent kinase inhibiting activity. Drugs comprising the compounds as effective ingredients are therefore expected to be useful as therapeutic or prophylactic agents for a protein kinase mediated disorder in which kinase is implicated, such as inflammatory disease, autoimmune disease, destructive bone disorder, cancer and/or tumour growth.