Functional Group Transformations in Derivatives Of
Article pubs.acs.org/joc Functional Group Transformations in Derivatives of 1,4- Dihydrobenzo[1,2,4]triazinyl Radical † § † ∥ † ‡ † ⊥ Agnieszka Bodzioch, , Minyan Zheng, , Piotr Kaszynski,́ *, , and Greta Utecht , † Organic Materials Research Group Department of Chemistry, Vanderbilt University, Nashville, Tennessee 37235, United States ‡ Faculty of Chemistry, University of Łodź,́ Tamka 12, 91403 Łodź,́ Poland *S Supporting Information ABSTRACT: Transformations of functional groups OCOPh, ’ − OCH2Ph, I, NO2, and CO2Me in Blatter s radical derivatives 1 5 were investigated in order to develop synthetic tools for incorporation of the benzo[1,2,4]triazinyl system into complex molecular architectures. Thus, basic hydrolysis of OCOPh or Pd-catalyzed debenzylation of OCH2Ph gave phenol functionality, which was acylated and alkylated. Pd-catalyzed Suzuki, Negishi, Sonogashira, and Heck C−C cross-coupling reactions of iodo derivatives 1c, 1d, and 2d ffi were also successful and e cient. Reduction of NO2 in 1e led to aniline derivative 1t, which was reductively alkylated with hexanal and coupled to L-proline. Selected benzo[1,2,4]triazinyl radicals were characterized by EPR and electronic absorption spectroscopy, and the results were analyzed in tandem with DFT computational methods. Lastly, the mechanism for formation of the 1,4- dihydrobenzo[1,2,4]triazine ring was investigated using the B3LYP/6-31G(2d,p) method. ■ INTRODUCTION little attention, and only a handful of derivatives have been Stable π-delocalized radicals are becoming important structural reported in the literature. This situation changed several years elements of materials for solar cells,1 energy storage,2 ago when Koutentis began systematic development of synthetic − electronic,3,4 and biological5 8 applications.9,10 Their incorpo- access to this class of radicals.
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