On the synthesis and reactivity of 4,10-dihydrobenzo-[b]thieno[2,3-e]thiepin-10-acetic acid and 5,10-dihydrobenzo[e]thieno[3,2-b]thiepin-10-acetic acid

A simple method to synthesize 4,10-dihydrobenzo[b]thieno[2,3-e]thiepin-10-acetic acid (8a) and 5,10-dihydrobenzo[e]thieno[3,2-b]thiepin-10-acetic acid (8b) starting from ketones la,b is described. The reactivity of the acid 8a has been investigated and some derivatives are reported.