Condensed heteroaromatic ring systems. XVIII. Palladium-catalyzed cross-coupling reaction of aryl bromides with (Z)-1-ethoxy-2-tributylstannylethene and its utilization for construction of condensed heteroaromatics

The palladium-catalyzed cross-coupling reaction of bromobenzenes or bromoheteroarenes such as pyridine, thiophene, indole with (Z)-1-ethoxy-2-tributylstannylethene gives good yields of the corresponding (Z)-1-ethoxy-2-(aryl and heteroaryl)ethenes. This method is effective for introducing an ethoxyethenyl group into an aromatic and heteroaromatic ring and is proved to have versatile utility for the construction of benzo[b]furan, indole, isocoumarin rings from 2-bromophenol, 2-bromoaniline, and 2-bromobenzoate derivatives.