A new and simple 'LEGO' system for the synthesis of 2,6-oligopyridines

Article abstract of DOI:10.1016/S0040-4039(98)01437-3

The condensation of α-arylglyoxals with carboxamidrazones 1 - 2 is the best method for the synthesis of aryl or hetaryl substituted 1,2,4-triazines 3 - 4. These 1,2,4-triazines can be easily transformed to pyridines 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 2,6-oligopyridines 8 - 11.