Development of Deuterium Labeling Method Based on the Heterogeneous Platinum Group Metal-Catalyzed C-H Activation

Deuterium (D) labeled compounds are utilized in various scientific fields such as mechanistic elucidation of reactions, preparation of new functional materials, tracers for microanalysis, deuterium labeled heavy drugs and so on. Although the H-D exchange reaction is a straightforward method to produce deuterated organic compounds, many precedent methods require expensive deuterium gas and/or harsh reaction conditions. A part of our leading research agendas is intended to the development of novel and functional heterogeneous platinum-group catalysts and the reclamation of unknown functionalities of existing heterogeneous platinum-group catalysts. During the course of the study, benzylic positions of substrates were site-selectively deuterated under mild and palladium-on-carbon (Pd/C) -catalyzed hydrogenation conditions in heavy water (D2O). Heat conditions promoted the H-D exchange reactivity and facilitated the H-D exchange reaction at not only the benzylic sites but also inactive C H bonds and heterocyclic nuclei. It is noteworthy that platinum-on-carbon (Pt/C) indicated a quite high affinity toward aromatic nuclei, and the H-D exchange reaction was strongly enhanced by the use of Pt/C as a catalyst under milder conditions. The mixed use of Pd/C and Pt/C was found to be more efficient in the H-D exchange reaction compared to the independent use of Pd/C or Pt/C. Furthermore, simple alkanes could also be efficiently deuterated under rhodium-on-carbon (Rh/C) -catalyzed conditions. The use of ruthenium-on-carbon (Ru/C) enabled the regiospecific and efficient deuterium incorporation at a-positions of alcohols and results were applied as a regio- and stereoselective multi-deuteration method of sugar derivatives.