Catalyst-transfer direct arylation allows multiple cross-coupling reactions to occur on a polyhalide substrate, even under substoichiometric conditions. For example, reacting one equivalent of 1,3,5-tribromobenzene with one equivalent of 2-methylthiophene generates only the starting tribromide and the corresponding 1,3,5-trithienylbenzene. Unfortunately, unselective C-H activation can occur in these reactions, leading to oligomeric side products. Utilizing several model systems and quantitative GCMS analysis, optimization afforded moderate to high yields of the desired product. Consistent with previous work, temperature, catalyst loading, and ligand choice appear to be the key factors in selective catalyst-transfer direct arylation. Related investigation of an air-stable palladium initiator will also be presented, which could enable controlled growth polymerization of conjugated monomers.

Catalyst-transfer direct arylation: Selectivity and potential initiators

249th National Meeting (2015)

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