Unerwartete Diels‐Alder‐ und Oxidations‐Reaktionen von Benzo[<i>c</i>]thiophenen

Abstract

Unexpected Diels‐Alder and Oxidation Reactions of Benzo[ c ]thiophenes The oxidation of thiophenes by peracids to form thiophene S ‐oxides could not be carried out with benzo[ c ]thiophenes. With the sterically hindered compound 1a the quinones 2 and 3 were produced whereas the anisyl‐substituted derivative 1b formed the sulfine 5 . Significantly different behaviour of 1a and 1b was also observed for the Diels‐Alder reaction with N ‐phenylmaleimide. The unexpected and unusual adduct 6 was the only product formed from 1a , with low yield though, whereas the normal Diels‐Alder adduct was obtained from 1b .