Cyclohepta[b]thiophene derivatives. Part-IV. Dehydrogenation of cyclohepta[b]thiophene and cyclohepta[c]thiophene derivatives

摘要

Cyclohepta[b]thiophenes 3 and cyclohepta[c]thiophene 4 on dehydrogenation with selenium give a complex mixture of dehydrogenated products. The formation of the identified products is explained through the initial homolytic cleavage at more than one particular bond in the cycloheptane moiety of 3 and 4. In all these cases ring contraction of the seven-membered ring of the thiophenes 3 and 4 is observed.