154067-81-9Relevant academic research and scientific papers
Bis(benzothieno)dithiine, a Valence Isomer of "Dithioxo-thioindigo"
Schroth, Werner,Hintzche, Ekkehard,Viola, Horst,Winkler, Ralf,Klose, Heike,et al.
, p. 401 - 408 (2007/10/02)
3-Mercaptobenzothiophene (1) is transformed with assistance of bases, especially of amines, into the benzothieno-annellated 1,2-dithiine 6 and not into the originally claimed "Dithioxo-thioindigo" trans-3.Primarily, the formation of 6 from 1 involves oxidation to the disulfide 4 which may also be used separately.Conceivable rationalizations are discussed.The same compound is accessible (in lower yield) by thionation of thioindigo with the aid of the Lawesson reagent.X-ray elucidation of 6 reveals a non-planar structure of the cyclic disulfide with a dihedral C-S-S-C-angle of 53 deg.Despite of the absence of any established chromophoric moiety, 6 is deeply red in the crystal and in solution, as it is representative for the "undisturbed" 1,2-dithiine system.Contrary to the usual behaviour of the non-annellated 1,2-dithiines, 6 displays no spontaneous sulfur extrusion under mild conditions, but only at high temperatures and in the presence of sulfur-binding agents, leading to the benzothieno-annellated thiophene 22.Moreover, 6 may be reduced to the dithiol 14 (or 13, respectively) and regenerated exclusively from this by oxidation.Further characteristic reactions of 6 are described (e.g. to the sulfoxide 18, to the pyridazine 19, and to the thiophosphoric ester 21). - Key Words: 1,2-Dithiines / Thioindigo / Thioketones / Disulphides, cyclic, molecular structure and reactions / Valence isomerization, electrocyclic / Thiophenes, derivatives of
