Redox Active Quinoidal 1,2,4-Benzotriazines

J Org Chem. 2018 Aug 17;83(16):9391-9402. doi: 10.1021/acs.joc.8b01311. Epub 2018 Jul 17.


Modifying the para-quinonimine 1,3-diphenyl-1,2,4-benzotriazin-7(1 H)-one (2a) ( E1/2-1/0 -1.20 V), by replacing the N1-phenyl by pentafluorophenyl, the C3-phenyl by trifluoromethyl, or the C7 carbonyl by ylidenemalononitrile, led to improved electron affinities as determined by cyclic voltammetry and computational studies. Combining structural changes further improved electron accepting abilities: the most electron deficient analogues ( E1/2-1/0 ∼ -0.65 V) involved combining the ylidenemalononitrile groups at C7 with the trifluoromethyl groups at C3. 1,2,5-Thiadiazolo fusion at C5-C6 did not affect the redox behavior but did enhance the UV-vis absorption profile. During the synthesis of the thiadiazolo analogues, 1,4-thiazino-fused analogues 6 were obtained in low yield, which thermally ring contract to the triazafluoranthenones 7. Compounds are fully characterized, and X-ray data are provided for selected analogues.

Publication types

  • Research Support, Non-U.S. Gov't