Answers are grounded in this paper and cite their sources.
The palladium-catalyzed direct arylation of SO(2)R-substituted thiophene derivatives was found to proceed regioselectively at C5 and in high yields using a variety of aryl bromides and as low as 0.5-0.1 mol % of phosphine-free Pd(OAc)(2) as the catalyst. For these reactions, sulfonyls, sulfonamides, or even a sulfonic ester as the thiophene substituents were successfully employed.
No takes yet. Share an insight, caveat, or question.
Bheeter et al. (2011) studied this question.
Synapse has enriched 10 related papers. Consider them for comparative context: