Efficient Synthesis and Properties of [1]Benzothieno[3,2-b]thieno[2,3-d]furans and [1]Benzothieno[3,2-b]thieno[2,3-d]thiophenes

Efficient syntheses of benzodithienofuran (BDTF; [1]benzothieno[3,2-b]thieno[2,3-d]furan) and benzodithienothiophene (BDTT; [1]benzothieno[3,2-b]thieno[2,3-d]thiophene) were achieved by the combination of an addition-elimination reaction, reduction, and Pd-catalyzed dehydrogenative cyclization. We also achieved the synthesis of π-extended BDTF and BDTT derivatives through the use of coupling reactions. The detailed physical properties of these compounds were investigated. The newly synthesized BDTFs exhibited strong fluorescence compared with BDTTs. 2,2′-Bis([1]benzothieno[3,2-b]thieno[2,3-d]furan) (BBTTF) exhibited p-type organic field-effect transistor (OFET) properties.