Selective Deuteration of pyridinecarboxylic acid derivatives by decarboxylation and D2O

Nowadays isotopic labeling -as presented in Deuterium-labelled compounds- is known as a unique technique to track the passage of an isotope through a reaction, metabolic pathway, or cell. The reactants are labeled by replacing specific atoms with their isotopes and then allowed them to undergo the certain reaction and therefore, this method is employed for mechanistic investigations of catalytic cycles and reaction pathways [1, 2].The most common protocol involves halogen/D exchange; this is usually mediated by strong bases, with the consequent limitation in functional group scope. In addition employing transition metal catalyst is believed as an alternative for this purpose [3]. In this work, a practical, mild and highly selective protocol for the monodeuteration of pyridinecarboxylic acid derivatives is presented. Decarboxylation process was promoted under Ag catalyst in DMSO/D2O media, facilitating the deutero-decarboxylation of heteroaromatic α-carboxylic acids in high yields with excellent levels of deuterium incorporation.