Steric and electronic limitations for the Dِtz benzannulation of aromatic alkynes

As part of an investigation into a new strategy for biaryl synthesis, the Dِtz benzannulation of a series of substituted aryl acetylenes was undertaken to determine possible steric and electronic effects exerted by the aryl group. In the ortho position it was found that methyl, methoxy, chloro and N-amide substituents give moderate to good yields of product, whereas carbonyl derivatives and the nitro group are deleterious.