The condensation of carboxamidrazones 1 with 1, 2-dicarbonyl compounds 2 is the best method for the synthesis of alkyl, aryl or hetaryl substituted 1, 2, 4-triazines 3–7. These 1, 2, 4-triazines can be easily transformed to pyridines 8–12 by [4+ 2] cycloaddition with bicyclo [2.2. 1] hepta-2, 5-diene followed by [4+ 2] cycloreversions of nitrogen and cyclopentadiene. This reaction sequence offers a new, simple and general access to branched ...
