ISSN:
0009-2940
Keywords:
1,2-Dithiines
;
Thioindigo
;
Thioketones
;
Disulfides, cyclic, molecular structure and reactions
;
Valence isomerization, electrocyclic
;
Thiophenes, derivatives of
;
Chemistry
;
Inorganic Chemistry
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
Bis(benzo[4,5]thieno)[3,2-c:2′,3′-e][1,2]dithiin, ein Valenzisomer von „Dithioxo-thioindigo“3-Mercaptobenzo[b]thiophene (1) is transformed with assistance of bases, especially of amines, into the benzo[b]-thieno-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°. Despite of the absence of any established chromonphoric 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 benzo[b]thieno-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 thiphosphoric ester 21).
Additional Material:
2 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/cber.19941270217
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