Novel ring chemistry of vitamin B6 with singlet oxygen and an activated ene: isolated products and identified intermediates suggesting an operable [3 + 2] cycloaddition.
Pyridoxine reaction with (1)O(2) in aqueous solution at neutral pH resulted in oxidation at the 2- and 6-positions of the pyridine ring and unprecedented ring contraction. Kinetic and low temperature studies provided observable intermediates by NMR spectroscopy. In addition, novel cycloaddition between pyridoxine and N-methylmaleimide, without N-alkylation and in water, suggest a common [3 + 2] cycloaddition with the 3-hydroxypyridine ring.
Department of Chemistry, St. Bonaventure University, St. Bonaventure, NY 14778, USA.
David
D
Samuel
Kirsten
K
Norrell
David G
DG
Hilmey
D003500:Cyclization; D007659:Ketones / Q000138:chemical synthesis* / Q000737:chemistry; D008958:Models, Molecular; D015394:Molecular Structure; D026082:Singlet Oxygen / Q000737:chemistry*; D025101:Vitamin B 6 / Q000737:chemistry*
D007659:Ketones; D026082:Singlet Oxygen; D025101:Vitamin B 6