Generation and Characterization of 1,3-Di-t-butyl- and 1,3-Di-t-butyl-4,6-dimethylthienothiophenes

Article abstract of DOI:10.1246/bcsj.65.2821

1,3-Di-t-butyl- and 1,3-di-t-butyl-4,6-dimethylthieno<3,4-c>thiophenes (1g and 1h) are generated by Pummerer dehydration of the corresponding sulfoxides (4 and 5, respectively) in boiling acetic anhydride and can be trapped with N-phenylmaleimide (NPM).Both endo- and exo-adducts are formed from 1g and NPM, while only exo-adduct is formed from 1h and NPM.Reduction and isomerization of the starting materials occur in the reactions of 4 and 5 with trifluoroacetic anhydride.The reaction of 5 with trifluoroacetic anhydride in the presence of 2,6-lutidine also gives 4,6-di-t-butyl-1-(trifluoro acetylmethylene)-3-methyl-1H,3H-thieno<3,4-c>thiophene.