Title compds. I [R2 = alkyl, alkynyl, alkynylalkyl, etc.; R3 = H, halo, alkyl, etc.; R4 = H, halo or alkyl; R5 = (un)substituted aryl which may optionally be fused with one or more heteroaryl], and their pharmaceutically acceptable salts, are prepd. and disclosed as inhibitors of cyclin dependent kinases (CDKs). Thus, e.g., II (R = H) was prepd. by substitution of III (prepn. given) with aniline, followed by deprotection. In in vitro kinase assays, II (R = pyrazo-1-yl) was found to possess an IC50 = 0.2 (.mu.M). Further disclosed are pharmaceutical compns. contg. I, methods of prepg. pharmaceutical formulations comprising one or more such compds., and methods of treatment, prevention, inhibition, or amelioration of one or more diseases assocd. with the CDKs using such compds. or pharmaceutical compns.