2,8- and 2,9-Diboryltetracenes as Useful Building Blocks for Extended π-Conjugated Tetracenes

Ir-catalyzed direct diborylation of tetracene gave a 1:1 mixture of 2,8- and 2,9-bis[(pinacolato)boryl]tetracenes, which were separated by recrystallization. These diboryltetracenes are useful building blocks for the regiospecific synthesis of extended pi-conjugated tetracenes directed to semiconductors for organic field-effect transistors (OFETs). Syntheses of thiophene-tetracene-thiophene, thiophene-tetracene-bithiophene-tetracene-thiophene, and thiophene-tetracene-anthracene-tetracene-thiophene pi-systems have been achieved on the basis of the 2,8- and 2,9-diboryltetracenes.