Novel Procedure for Synthesis of Triphenodithiazines

Abstract

The syntheses of triphenodithiazine (5, 12-dithia-7, 14-diazapentacene) [5a] and its homolog were possible by dechlorination of their 6, 13-dichloro derivatives which were prepared by condensation of aminobenzenethiols with chloranil in good yield. The dechlorination was easily carried out by tin powder in polyphosphoric acid. For example, 6, 13-dichloro derivative of [5a] [4a] was converted to [5a] in 52.7% yield.
Similarly, 3, 10-dichloro [413], 3, 10-dimethyl [4d], 3, 10-dimethoxy [4e], 3, 4: 10, 11-dibenzo [4f] derivatives of [4a] were reduced to corresponding chlorine free compounds [5]. As a result, a new preparative procedure for synthesis of [5] from 6, 13-dichlorotriphenodithiazines [4] was developed. Replacement of chlorines by hydrogens in these heterocycles brought about a decrease in melting point and hypsochromic shifts in electronic spectrum as in the case of triphenodioxazines.