The Photochemical Mediated Ring Contraction of 4H-1,2,6-Thiadiazines To Afford 1,2,5-Thiadiazol-3(2H)-one 1-Oxides

Emmanouil Broumidis, Christopher Thomson, Brendan Gallagher, Lia Sotorríos, Kenneth George McKendrick, Stuart Alan Macgregor*, Martin J. Paterson, Janet Lovett, Gareth O. Lloyd, Georgina Margaret Rosair, Andreas Kalogirou, Panayiotis Koutentis*, Filipe Vilela*

*Corresponding author for this work

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1,2,6-Thiadiazines treated with visible light and 3O2 under ambient conditions are converted into difficult-to-access 1,2,5-thiadiazole 1-oxides (35 examples, yields of 39–100%). Experimental and theoretical studies reveal that 1,2,6-thiadiazines act as triplet photosensitizers that produce 1O2 and then undergo a chemoselective [3 + 2] cycloaddition to give an endoperoxide that ring contracts with selective carbon atom excision and complete atom economy. The reaction was optimized under both batch and continuous-flow conditions and is also efficient in green solvents.
Original languageEnglish
Pages (from-to)6907-6912
Number of pages6
JournalOrganic Letters
Issue number37
Early online date11 Sept 2023
Publication statusPublished - 22 Sept 2023

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