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Bis(benzo[4,5]thieno)[3,2‐ c :2′,3′‐ e ][1,2]dithiin, ein Valenzisomer von „Dithioxo‐thioindigo”︁
Author(s) -
Schroth Werner,
Hintzsche Ekkehard,
Viola Horst,
Winkler Ralf,
Klose Heike,
Boese Roland,
Kempe Rhett,
Sieler Joachim
Publication year - 1994
Publication title -
chemische berichte
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 0009-2940
DOI - 10.1002/cber.19941270217
Subject(s) - chemistry , thiophene , pyridazine , sulfoxide , dihedral angle , moiety , reagent , sulfone , dithiol , stereochemistry , benzothiophene , medicinal chemistry , crystal structure , polymer chemistry , crystallography , molecule , organic chemistry , hydrogen bond
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 CSSC‐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 ).