4,7-Di(thiophen-2-yl)benzo(c)(1,2,5)thiadiazole → Tributyltin bromide

Participants

Reaction Steps

The 4,7-bis(5-bromothien-2-yl)-2,1,3-benzothiadiazole is traditionally prepared from 4,7-bis(thien-2-yl)-2,1,3-benzothiadiazole, which in turn is prepared by the Stille coupling reaction of 4,7-dibromo-2,1,3-benzothiadiazole with tributyl(thien-2-yl)stannane as described by Kitamura et al., Chem. Mater., Vol. 8, 1996, pp. 570–578. Unfortunately, tributyl(thien-2-yl) stannane is a highly toxic and costly material that produces a toxic by-product tributyltin bromide. The process is further disadvantaged because the subsequent bromination reaction is carried out in a mixture of N-bromosuccinimide, chloroform, and acetic acid, which requires numerous crystallizations of the product to obtain a suitably pure material in the subsequent copolymerization reaction.

Provenance & Evidence