Synthesis and Electrochemical Study of Benzothiazine and Phenothiazine Derivatives

Article abstract of DOI:10.1021/jo00227a021

A number of benzothiazine and phenothiazine derivatives are prepared by reaction of 2-mercaptoaniline and cyclic β-diketo compounds or by reaction of bidentate nucleophiles on 4-chloro-3-nitrocoumarin by using the HSAB principle.The topological resonance energies per ?-electron (TREPE's) are calculated for nine benzothiazine and phenothiazine derivatives and correlated with the first reversible peak potentials.The analysis of the data shows a good correlation between the TREPE values and the oxidation potentials.The chemical behavior of the electrochemically generated radical cations of the two related heterocyclic systems: 6,12-dihydro<1>benzopyrrano<3,4-b><1,4>benzothiazin-6-one (1) and 2,3-dihydro-2,2-dimethylphenothiazin-6(1H)-one (2) are examined by using the electroanalytical techniques and preparative controlled potential electrolysis.HMO calculations are used to predict the most reactive sites toward the nucleophilic attack.