Selective Multiple Magnesiations of the Thieno[3,2-b]thiophene Scaffold

A full functionalization of all four positions of the thieno[3,2-b]thiophene scaffold was achieved. Starting from 2,5-dichlorothieno[3,2-b]thiophene, magnesiation of the 3- and 6-position using tmpMgCl center dot LiCl furnishes, after trapping with various electrophiles, 3,6-difunctionalized dichlorothieno[3,2-b]thiophenes. Subsequent dechlorination and regioselective metalation or regioselective magnesiurn insertion into the C Cl bond provides fully functionalized thieno[3,2-b]thiophenes. Furthermore, new condensed heterocycles and small oligomers of these compounds with potential applications in material chemistry have been prepared.