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Manganese-catalyzed selective C–H activation and deuteration by means of a catalytic transient directing group strategy
A novel manganese-catalyzed C-H activation methodology for selective hydrogen isotope exchange of benzaldehydes is presented. Using D2O as a cheap and convenient source of deuterium, the reaction proceeds with excellent functional group tolerance. Highortho-selectivity is achieved in the presence of catalytic amounts of specific amines, whichin situform a transient directing group. © The Royal Society of Chemistry 2021.
Ruthenium-Catalyzed Deuteration of Aromatic Carbonyl Compounds with a Catalytic Transient Directing Group
A novel ruthenium-catalyzed C−H activation methodology for hydrogen isotope exchange of aromatic carbonyl compounds is presented. In the presence of catalytic amounts of specific amine additives, a transient directing group is formed in situ, which directs selective deuteration. A high degree of deuteration is achieved for α-carbonyl and aromatic ortho-positions. In addition, appropriate choice of conditions allows for exclusive labeling of the α-carbonyl position while a procedure for the preparation of merely ortho-deuterated compounds is also reported. This methodology proceeds with good functional group tolerance and can be also applied for deuteration of pharmaceutical drugs. Mechanistic studies reveal a kinetic isotope effect of 2.2, showing that the C−H activation is likely the rate-determining step of the catalytic cycle. Using deuterium oxide as a cheap and convenient source of deuterium, the methodology presents a cost-efficient alternative to state-of-the-art iridium-catalyzed procedures. © 2021 The Authors. Chemistry - A European Journal published by Wiley-VCH GmbH