OXIDATIVE DESULFURIZATION OF ELECTRON-DONATING 5,5,7,7-TETRAARYL-5,7-DIHYDRODIBENZOc,eTHIEPINS AND THE RELATED HETEROCYCLES: GENERATION OF DICATIONIC DYES UPON TWO-ELECTRON OXIDATION

摘要

Upon oxidation of the title heterocycle (1A) with dimethylamino groups, elemental sulfur is extruded to form dicationic dye (1B(2+)), from which the starting dibenzothiepin derivative was generated by the reaction with Na2S. The bay-region substituents enhance configurational stability, so that, the optically pure heterocycles (M)-2A, (M)-3A) can be obtained in terms of helicity of one-handedness by starting with the corresponding optically pure dicationic dyes (R)-2B(2+), (R)-3B(2+)). Similar oxidative desulfurization occurs in dibenzo-1,5-oxathiocin 4A, a structurally related 8-membered heterocycle.