Effect of the type of linkage between phenyl groups on the structure and photochemical properties of 2,2-diaryl-substituted pyridoannelated [2H]-chromenes

Article abstract of DOI:10.1007/BF02503478

Three 2,2-diaryl-substituted pyridoannelated [2H]-chromenes have been studied by X-ray diffraction analysis. Bonding of the benzene rings through bridges of different nature and with different length affects substantially the orientation of the benzene rings, steric interactions at the C center, the conformation of the molecule, and the C-O bond length. A correlation between the photocolorability of chromenes under study and the orientation of the benzene rings with respect to the C-O bond, which provides different prerequisites to stabilization of the C(1)-centered cation formed upon cleavage of the C-O bond, was established. The effect of the orientation of the benzene rings on the dark reaction of ring closure was found.