SYNTHESIS AND TRAPPING OF 4H-THIENO[3,4-C]PYRROLE AND 5H-THIENO[3,4-C]PYRROLE

The synthesis and trapping of the parent compound and derivatives of the thieno[3,4-c]pyrrole ring system are reported. Intramolecular 1.3-dipolar cycloaddition of the azides 9a-d and subsequent acid-catalysed 1,3-dipolar cycloreversion of the thienopyrrolotriazoles 10a-d afforded the parent compound 3a and its derivatives 3b-d. Trapping of 3a-d by 1,3-dipolar cycloaddition with N-phenylmaleimide via the azomethine ylide 2a-d gave cycloadducts 14a-d and 15a-d. Reactions of the halides 8a, c, d and g with benzylamine produced N-benzylazomethine ylides 18a. c. d and g which were also trapped by N-phenylmaleimide to give the cycloadducts 19a, c, d and g.