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

Added on:
5 Nov, 2023

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.

  • Emmanouil Broumidisa, Christopher G. Thomsona, Brendan Gallaghera, Lia Sotorríosa, Kenneth G. McKendricka, Stuart A. Macgregor*a, Martin J. Patersona, Janet E. Lovettb, Gareth O. Lloydc, Georgina M. Rosaira, Andreas S. Kalogiroud,e, Panayiotis A. Koutentis*e, and Filipe Vilela*a,f
  • aInstitute of Chemical Sciences, School of Engineering & Physical Sciences, Heriot-Watt University, Edinburgh, EH14 4AS, United Kingdom
  • bSUPA School of Physics and Astronomy and BSRC, University of St Andrews, St. Andrews, KY16 9SS, United Kingdom
  • cJoseph Banks Laboratories, School of Chemistry, University of Lincoln, Brayford Pool, Lincoln LN6 7TS, United Kingdom
  • dDepartment of Life Sciences, School of Sciences, European University Cyprus, 6 Diogenes Str., Engomi, P.O. Box 22006, 1516 Nicosia, Cyprus
  • eDepartment of Chemistry, University of Cyprus, P.O. Box 20537, 1678 Nicosia Cyprus
  • fContinuum Flow Lab, School of Engineering & Physical Sciences, Heriot-Watt University, Edinburgh, EH14 4AS, United Kingdom
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