6-(Arylvinylene)-3-pyridinylboronic esters. Part 2: Versatile building blocks for push-pull nonlinear optical chromophores

This paper describes a general approach for the synthesis of push-pull 6,6′-disubstituted-3,3′-bipyridine chromophores. As examples, 6-(4-ethanol-2-thienylvinylene)-5-methyl-3-bromopyridine, 6-(4-hydroxy-phenylvinylene)-5-methyl-3-bromopyridine, and the corresponding 3-pyridinylboronic esters have been prepared as building blocks end-capped with electron donor groups (D). 6-(4-Cyano-phenylvinylene)-5-methyl-3-bromopyridine, and 6-(4-cyano-phenylvinylene)-3-bromopyridine have been synthesized as building blocks end-capped with electron acceptor groups (A). {A x D} type cross-couplings via Suzuki reaction gave the push-pull chromophores (I) and (II) in high yields and multigram scales.