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Photochemical Reaction of 2,4,4,6-Tetraaryl-4H-Pyrans and -4H-Thiopyrans with Colour Change by a 1,5-Electrocyclic Reaction. X-Ray Molecular Structure of 4-Methyl-2,3,6-triphenyl-2H-thiopyran

DOI: 10.1039/P29910002061

Source and publish data:

Journal of the Chemical Society. Perkin transactions II p. 2061 - 2066 (1991)

Update date:2022-07-30

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Authors:

Mori, YukieMori, Yukie

Maeda, KokoMaeda, Koko

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Article abstract of DOI:10.1039/P29910002061

2,4,4,6-Tetraphenyl-4H-pyran and -4H-thiopyran exhibited a photochemical colour change in the solid state.On irradiation in solution, 2,4,4,6-tetraphenyl-4H-pyran gave 1,3,5,6-tetraphenyl-2-oxabicyclo<3.1.0>hex-3-ene, while the 4H-thiopyran gave 1,3,5,6-tetraphenyl-2-thiabicyclo<3.1.0>hex-3-ene as an initial photoproduct, followed by further transformation into 2,3,4,6-tetraphenyl-2H-thiopyran. 4-(4-Bromophenyl)-2,4,6-triphenyl-4H-pyran, 4-(4-methylphenyl)-2,4,6-triphenyl-4H-pyran, and 4-(bromophenyl)-2,4,6-triphenyl-4H-thiopyran also showed photochemical colour changes and finally gave both the phenyl-migrated and the (substituted phenyl)-migrated products in comparable yields in each case. 4-Methyl-2,4,6-triphenyl-4H-thiopyran showed no photochemical colour change in the solid state, but in solution it afforded 4-methyl-2,3,6-triphenyl-2H-thiopyran, whose structure was confirmed by X-ray analysis.Based on comparison with the photochemical behaviour of 2,4,4,6-tetraphenyl-1,4-dihydropyridine and 2,2,4,6-tetraphenyl-1,2-dihydro-1,3,5-triazine, a six-membered ylide was proposed as the coloured photochemical intermediate.

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Product name:2-Oxabicyclo[3.1.0]hex-3-ene, 6-(4-bromophenyl)-1,3,5-triphenyl-

Cas No:139118-26-6

139118-26-6

R&D Labs maybe for 139118-26-6

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