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![Cercosporin-Photocatalyzed [4+1]- and [4+2]-Annulations of Azoalkenes Under Mild Conditions](/_next/image?url=https%3A%2F%2Fcloudfront.jove.com%2FCDNSource%2Fteasers%2F60786.jpg&w=3840&q=50)
Cercosporin-Photocatalyzed [4+1]- and [4+2]-Annulations of Azoalkenes Under Mild Conditions
Published on: July 17, 2020
Ring-Fused 1,4-Dihydro[1,2,4]triazin-4-yls through Photocyclization
Paulina Bartos1, Victor G Young2, Piotr Kaszyński1,3,4
1Faculty of Chemistry, University of Łódź, 91-403 Łódź, Poland.
Abstract:
Halogen lamp irradiation of benzo[e][1,2,4]triazines 2[X] in CH2Cl2 solutions leads to planar ring-fused 1,4-dihydro[1,2,4]triazin-4-yl radicals 1 through a novel, potentially general, cyclization mechanism. The scope and efficiency of the method were established for unsubstituted and ortho-substituted (X = NH2, Br, NO2) phenoxy, naphthyloxy, and quinolinoxy derivatives 2[X]. The regioselectivity of 2[X] photocyclization was rationalized with DFT computational methods. Radicals 1 were characterized by spectroscopic (UV-vis, EPR), electrochemical, and XRD methods.
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