Polybrominated anthracenes: selective synthesis of tetrabromoanthracenes as precursors for the corresponding tetracyanoanthracenes

Selective and efficient methods for the preparation of both 2,7,9,10-tetrabromoanthracene 11 and 2,6,9,10-tetrabromoanthracene 12 are described. Photobromination of 2,9,10-tribromoanthracene 8 resulted in the formation of only one stereoisomeric heptabromide 10. Whilst thermal aromatization of the trans,cis,trans-1,2,3,4,6,9,10-heptabromo-1,2,3,4-tetrahydroanthracene 10 gave mainly 2,6,9,10-tetrabromoanthracene 12, the pyridine-induced elimination yielded 2,7,9,10-tetrabromoanthracene 11 as the only final product. Tetrabromide 11 was transformed into 2,7,9,10-tetracyanoanthracene 14, by copper-assisted nucleophilic substitution reaction, as a potential photoconductive product.