Iridium-Catalyzed Formyl-Selective Deuteration of Aldehydes.

We report the first direct catalytic method for formyl-selective deuterium labeling of aromatic aldehydes under mild conditions, using an iridium-based catalyst designed to favor formyl over aromatic C-H activation. A good range of aromatic aldehydes is selectively labeled, and a one-pot labeling/olefination method is also described. Computational studies support kinetic product control over competing aromatic labeling and decarbonylation pathways.