Formation of Five- and Six-membered Heterocyclic Rings by Radical Cyclization

Cascade cyclization of 1-(2-yl-3-phenylprop-2-enyl)-6-oxo-1,6-dihydropyridine-2-carbonitrile radical: Mechanistic insights from DFT study

“…The resulting five-and six-membered radicals have been suggested to be capable of transforming into each other via neophyl-like rearrangements [45,[113][114][115]. However, most of the presumptions for the neophyl-like rearrangement mechanism have proved to be improbable because the ring-fused intermediates on rearrangement pathways are usually high-lying and the neophyl-like rearrangements cannot effectively compete with the direct oxidation and reduction of the 5-exo and 6-endo radicals [44,116].…”

“…Generally, 5-exo and 6-endo pathways are competitive in intramolecular radical cyclization reactions [113][114][115][116]. The resulting five-and six-membered radicals have been suggested to be capable of transforming into each other via neophyl-like rearrangements [45,[113][114][115].…”

Microwave-assisted synthesis of quinoline alkaloids: 4-Methoxy-1-methyl-2-quinolinone and its analogs

“…Among the quinolines, some facile precursors are available which could be transformed into desired quinoline alkaloids using various reactions. [7][8][9] For instance, 4-hydroxy-2-quinolinone is an important biosynthetic 7 and synthetic 8,9 precursor of quinoline alkaloids.…”

Effect of Substitution in Stannic Chloride–Mediated Heterocyclization of 4‐Allyl‐3‐hydroxyquinolin‐2(1H)‐ones

“…Recently, we reported N-iodosuccinimide (NIS) -mediated heterocyclization of ortho-cyclohex-2 0 -enylphenols, [5] 3-cyclohex-2 0 -enyl-4-hydroxycoumarin, [6] and 3-allyl-4-hydroxycoumarin [7] in acetonitrile at 0 -58C in almost quantitative yield. We have also reported heterocyclization using pyridine hydrotribromide, [8,9] mercuric acetate, [10] and hexamethylenetetramine hydrotribromide.…”