Thiirans, photochemistry

To study the photochemistry of the dithiins 51b (Scheme 13) in solution, the compounds were irradiated with visible light at —60 to —75 °C to afford the thiiranes 118 in excellent yields which were characterized by H and NMR spectroscopy. Upon warming or further exposure to light, the thiiranes 118 afforded the thiophenes 119 (Scheme 29) <2000MI159, 1996JA4719>. 

Topics which have formed the subjects of reviews this year include theoretical studies of the photochemistry of thiiranes, photoaddition of amines to aryl olefins and arenes, the synthesis of heterocyclic compounds, photoamination directed towards the synthesis of heterocycles, selective addition of organic dichalcogenides to carbon-carbon unsaturated bonds, photocyclisation mechanisms of c/5-stilbene analogues, synthetic utility of the photocyclisation of aryl-and heteroarylpropenoic acids, photochromic diarylethenes, spiropyrans, cy-clophanes, and polycondensed aromatics," photochromic organic media, photophysics and photochemistry of P-carbolines, and the photochemical synthesis of macrocycles.Chirality switching by light has also been described. ... 

The photochemistry of thiirans and thiirens has been reviewed. exo-2,3-Epithionorbom-5-ene (58) decomposes photochemically or thermally to 2-thiabicyclo[3,2,l]octa-3,6-diene (59) and other products by a stepwise process. ... 

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