Study On The Synthesis Of Deuterium-labeled Compounds Catalyzed By Base

Deuterium labeled compounds have been widely used in many research fields.Hydrogen isotope exchange（HIE）has shown strong vitality and extensive research interest in recent decades due to its convenient and efficient synthesis steps.However,it is still a great challenge to achieve selective HIE at specific sites of compounds.At the present stage,few studies focus on the hydrogen deuterium exchange of polychlorinated biphenyls（PCBs）,and fewer hydrogen deuterium exchange strategies can achieve their selective H/D exchange.Although there are reports occasionally involving the deuteration of chlorobenzene,which usually have low deuteration level and poor selectivity.In addition,the selective hydrogen deuterium exchange of pyridine and its derivatives mainly focuses on the ortho-position of nitrogen at present,and the reports on the selective hydrogen deuterium exchange reaction strategy to achieve its distal-positions are very rare and challenging.Therefore,the following solutions to the above problems are proposed:（1）Polychlorinated biphenyls are one of the most common and harmful environmental pollutants at present.With the rapid development of mass spectrometry analysis methods,it is very important to develop a synthesis method of deuterium labeled polychlorinated biphenyls for the analysis and detection of this pollutant.Therefore,a new scheme of hydrogen deuterium exchange reaction of polychlorinated biphenyls catalyzed by strong base in DMSO-d₆/D₂O solution is proposed.The reaction mechanism involved in this scheme is also explored by DFT theory study.This scheme achieves excellent deuterium incorporation and good ortho selectivity for a variety of polychlorinated biphenyls and their derivatives,showing considerable prospects for the application of PCBs in future mass spectrometry analysis.（2）Pyridine is an important component of many natural products,agricultural chemicals,chemical industrial products,and also the core structure of many drugs.Therefore,based on our previous work,a new strategy to achieve selective hydrogen deuterium exchange at the distal-sites of pyridine and its derivatives using a strong base catalytic system in the presence of 18-crown-6 is proposed.This strategy has extensive functional group applicability and can maintain good regional selectivity for a variety of substrates while achieving high deuteration levels.Through the control experiment,it is found that the presence of 18-crown-6 was very important for the regioselectivity of the system.