Non-classical Thienothiophens

The ability to form adducts was also found in the so-called non-classical thienothiophene (4). As described above (see Section II,B), the sulfoxide of 4,6-dimethyl-l//,3i/-thieno[3,4-c]thiophene (143) and l,3,4,6-tetraphenylthieno[3,4-c]thiophene 049) react with A -phenyl-maleimide to form endolexo pairs of adducts 144, 145 and 150,... 

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