A novel synthesis of fused pyrazole systems as antimicrobial agents.

The pyrazolo[3,4-b]pyridine derivatives 3 could be prepared by condensing compounds 1 with the 3-aminopyrazolone derivative 2. The pyrazolo[5,2-b]-1,3-oxazine derivative 11 and polyfunctionally substituted 1,4-dihydropyridines 15, 18 were also synthesized. Some of the obtained compounds were tested for their antimicrobial activity.