Crystal structure of a photolysis product of vitamin B6: A pyridodihydrofuran-condensed skeleton compound of pyridoxal 5′-phosphate.

An aqueous solution dissolving pyridoxal 5′-phosphate (PLP) was exposed to sun-light at room temperature to yield a photolysis product, 4b,9b-dihydro-4b,9b-dihydroxy-1,6-dimethyl-4,9-bis(phosphonooxymethyl){pyrido[3′,4′:2,3]furo[4,5- b ]}pyrido[4,3- d ]furan ( 1 ), whose structure was crystallographically determined. The product 1 was found to be a novel C(sp 3 )–C(sp 3 ) side-sharing pyridodihydrofuran-condensed skeleton compound with the two pyridodihydrofuran planes taking a ‘V-shape’-like molecular configuration. Hydrogen bonding patterns of molecules of 1 in the crystal lattice are analyzed by the graph set approach. The most probable mechanism for the formation of 1 is described. [ABSTRACT FROM AUTHOR]