Rhodium(III)‐catalyzed Construction of D‐A Type Polyheteroaromatics with Fluorinated Benzothiadiazole as a Modifiable Acceptor Block.

An efficient pathway to a new family of fluorinated polyheteroaromatic D‐A molecules has been developed. The method is based on the Rh(III)‐catalyzed regioselective [4+2]‐annulation of N‐(pivaloyloxy)‐benzamides with 4‐ethynyl‐5,6‐difluoro‐7‐(p‐methoxyphenyl)‐2,1,3‐benzothiadiazole as a key step followed by the aromatization/Suzuki coupling sequence to furnish the target D‐A systems with modifiable acceptor block. The discovered difference in reactivity between ArB(OH)2 and ArBPin allows performing a divergent modification of BTD acceptor block by the manipulation of aryl boronic reagents in the ortho‐selective C−F activation of the fluorinated BTD moiety under Suzuki reaction conditions to furnish new D1‐π‐A‐D2 systems in good yields. Such step‐by‐step modification of the acceptor block has been achieved by Pd‐catalyzed C−F bond activation under isoquinoline ring assistance for the first time. [ABSTRACT FROM AUTHOR]