Role of substituents in the Hofmann–Löffler–Freytag reaction. A quantum-chemical case study on nicotine synthesis

The Hofmann–Löffler–Freytag (HLF) reaction can be successfully used to synthesize saturated heterocyclic nitrogen-containing nature-derived pharmaceuticals such as nicotine and its derivatives.

Utility Of 6-Azauracils In Synthesis of New Poly Heterocyclic Nitrogen Systems Bearing 1,2,4-Triazine Moiety as Antioxidant Probes.

Synthesis of new poly heterocyclic nitrogen systems containing 1,2,4-triazine moiety such as pyrazolines, pyrazolones, phthalazinone and 1,2,4-triazinone (9-17) have been deduced from hydrazinolysis of 3,5-dichloro-6,1-dihydro-1,2,4-triazine (2) which produced from the interaction between 6-azauracil (1) with POCl3/PCl5. Heterocyclization of 3,5-dihydrazino-1,2,4-triazine (7) by reaction nitrogen / oxygen / halogen bifunctional reagents in different mediums and conditions yielded the targets 9-17 respectively. Former structure of the products has been established from their elemental analysis and spectral data (UV, IR, 1H/13C NMR and Mass). All the new targets obtained evaluated as antioxidant probes in compare with ascorbic acid in 1,1-diphenyl-2-picrylhydrazyl (DPPH) as a standard, were the compounds 11>10>8>12>13 are more active probes.