Synthesis of Unsymmetric Monosubstituted and Disubstituted Dinaphthothiophenes

Dinaphthothiophenes (DNTs) are a class of compounds with potential uses in organic semiconductors and the synthesis of unsymmetric catalysts. Symmetrical or asymmetrical addition of functional groups to the DNT structure may be desired for steric bulk in binaphthyl catalyst synthesis or tuning the electronic properties of semiconductors. Thus, versatility of functional group addition is a great asset in DNT synthesis. Until now, no versatile and concise methods for the synthesis of unsymmetrically substituted DNTs have been reported. Herein, we report three synthetic routes for the creation of three different classes of DNTs. Each route involves the successive addition of two functionalized styryl groups to a thiophene ring, followed by a photocyclization to form the desired asymmetric DNT. Various novel unsymmetrically monosubstituted and disubstituted dinaphtho[2,1-b:1',2'-d]thiophenes, dinaphtho[1,2-b:1',2'-d]thiophenes, and dinaphtho[1,2-b:2',1'-d]thiophenes were synthesized from 2-bromothiophene, 2,4-dibromothiophene, and 3,4-dibromothiophene in three or four steps. These methods can be used to synthesize a wide variety of unsymmetrically functionalized DNTs.