Rhodium Catalysed Direct Arylation of Pyridines and Quinolines

Pyridines are often difficult to functionalise, particularly by aryl groups and often a “de novo” synthesis may be required when cross-coupling methods fail.  A new reaction from the group of Ellmann at University of California, Berkley allows arylation of pyridines in the 2-position, though unfortunately the reaction does not work with pyridine itself.  Another disadvantage at present is that the paper measures yield based on the arylating agent, not the pyridine/quinoline, and the small print indicates that 3-6 mole equivalents are currently required.  This may help stabilise the active catalyst.  (J Am Chem Soc, 2008, 130, 14926).

The paper does not comment on the use of dioxane at temperatures well above its boiling point.

Previous papers have examined alkylation of pyridines (J Am Chem Soc, 2008, 130, 2493).