Photoisomerization of allyl ethers: syntheses of vinyl ethers

Photochemical Transformations of Some 2-(5-Methylthiophen-2-yl)-3-[(naphthalen-2-yl)methoxy]-4H-chromen-4-ones Involving Type-II Process

“…1 H NMR (300/400 MHz) and 13 C NMR (75.4 MHz) spectra were recorded on a Bruker spectrometer using TMS as an internal standard. IR spectra were recorded on an MB3000 FT-IR with HORIZON MB TM FTIR software from ABB Bomen using KBr pellets.…”

Chromones and bischromones: an account of photoinduced reactions

“…When electron captive group (-COOEt) was present upon the allyloxy group 65, then initially formed 1,4-biradical 66 undergo mesomerization to yield vinyl ethers as the photoproduct, 44 67. …”

Photochemistry of 3-alkoxychromones: photocyclisation of 2-aryl-6-chloro-3-{(thiophen-2-yl)methoxy}chromones

“…[1][2][3][4] The products obtained, depend upon the nature of the substituents present in the substrates, for example, 2-alkyl-3-arylcyclohex-2-enones 5 and 3-alkoxy-2-phenyl-4-oxo-4H-1-benzopyran, [6][7][8] afforded the photocyclised angular products whereas 3-methoxy-2-methylchromones 9 have been found to furnish the novel dimeric oxetanol. In 3-alkoxy-2-arylchromones, the synthetic applications of these γ-hydrogen abstractions include the formation of vinyl ethers, 10 spiropyrans, 11 pyranopyrones, 12 pyranoalcohols, 13 angular tetracyclics 14 etc. In these phototransformations, the primary reaction is the n-π * excitation of the C=O group that subsequently abstracts hydrogen from the 3-alkoxy group leading to the formation of the 1,4-biradical.…”

“…In these phototransformations, the primary reaction is the n-π * excitation of the C=O group that subsequently abstracts hydrogen from the 3-alkoxy group leading to the formation of the 1,4-biradical. [5][6][7][8] The nature of the 3-alkoxy group has been found to have a profound effect on the fate of 1,4-biradical 10,13 to form the mesomeric biradicals. To examine the effect of (thiophen-2-yl)methoxy group at 3-position of the chromones with different 2-aryl groups and also to study the possibility of photo-transposition 15 reactions of the thiophene when tied to the chromones, in this work we report the synthesis and the photolytic behavior of the chromones 2(a-g).…”