Thiophene analogues of carcinogenic polycyclic hydrocarbons. Elbs pyrolysis of various aroylmethylbenzo[b]thiophenes

Abstract
The synthesis of benzonaphthothiophenes 9 and 10 and of benzophenanthrothiophenes 14–17 through Elbs cyclodehydration of ortho‐methylated aroylbenzo[b]thiophenes is described. The occurrence of a rearrangement of the thiophene ring in the course of the cyclization is discussed as well as the influence of the temperature on a concurrent cyclodehydration process. Several of these poly‐condensed thiophenes were found carcinogenic in mice.