Palladium-catalyzed decarboxylative cyanation of aromatic carboxylic acids using [13C] and [14C]-KCN

The development of robust and straightforward methods to efficiently label aromatic moieties starting from simple and convenient radio-synthetic sources still represents a considerable challenge. In this report, a new palladium-catalyzed decarboxylative cyanation protocol has been described. This procedure utilizes [14C]-labeled potassium cyanide, one of the simplest and commercially available sources of carbon-14. Under the optimized reaction conditions, a series of [13C] and [14C]-aromatic nitriles were easily prepared (12–74% yield starting from potassium cyanide). The usefulness of this methodology is highlighted by a rare example of a formal two-step [12C]–[14C] carbon isotope exchange. The current synthetic approach may represent a promising alternative to traditional preparations of relevant building blocks such as labeled aromatic nitriles.