Modified Chemoselective Reduction and Consecutive Regioselective Deuteration Reaction Catalyzed by B(C6F5)3

An efficient chemoselective reduction of isatin derivatives using catalyst B(C₆F₅)₃, benzyldimethylsilane, and H₂O is described. Notably, a small amount of water is shown to be a highly effective reaction promoter that decreases the reaction time and temperature for the synthesis of indolin-3-ones. Moreover, using method, excellent deuterium incorporation is achieved via the catalytic α-deuteration of indolin-3-ones using B(C₆F₅)₃ and D₂O.

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.

Catalytic Hydrogen Isotope Exchange Reactions in Late-Stage Functionalization

The introduction of deuterium and tritium into molecules is of great importance in drug discovery. Many attempts have been made to develop late-stage hydrogen isotope exchange (HIE) reactions to avoid multistep syntheses using commercially available labeled precursors. In this review, we summarize recent progress in catalytic HIE reactions, with our main focus on their applications in the late-stage labeling of bioactive complex molecules and pharmaceuticals1 Introduction

2 Non-Transition-Metal-Catalyzed Hydrogen Isotope Exchange

2.1 Organocatalysis

2.2 Photoredox Catalysis

3 Transition-Metal-Catalyzed Hydrogen Isotope Exchang

3.1 Palladium

3.2 Ruthenium

3.3 Iridium

3.4 Other Metals

4 Summary

The unique catalytic role of water in aromatic C–H activation at neutral pH: a combined NMR and DFT study of polyphenolic compounds

NMR and DFT studies demonstrate the unique catalytic role of H₂O in aromatic C–H activation which results in a reduction of ΔG^# values by a factor of 20–30 kcal mol⁻¹.

B(C6F5)3-Catalyzed α-Deuteration of Bioactive Carbonyl Compounds with D2O

An efficient deuteration process of α-C-H bonds in various carbonyl-based pharmaceutical compounds has been developed. Catalytic reactions are initiated by the action of Lewis acidic B(C₆F₅)₃ and D₂O, converting a drug molecule into the corresponding boron-enolate. Ensuing deuteration of the enolate by in situ-generated D₂O⁺-H then results in the formation of α-deuterated bioactive carbonyl compounds with up to >98% deuterium incorporation.

Synthesis of deuterium-labeled crizotinib, a potent and selective dual inhibitor of mesenchymal-epithelial transition factor (c-MET) kinase and anaplastic lymphoma kinase (ALK)

To more accurately and rapidly achieve quantitative detection of clinical crizotinib samples, stable isotope labeled crizotinib was required as an internal standard. We have developed a method to prepare racemic [D₉ ] crizotinib using a base-catalyzed H/D exchange of both nitroso compound 2 and the acetophenone compound 6 with D₂ O and NaBD₄ reduction of 7 as the key steps to introduce the 9 deuterium atoms. Starting with 4-hydroxypiperidine, 14-step synthesis furnished the desired racemic [D₉ ] crizotinib 18. The deuterium-labeled compound 18 with the chemical purity of 99.62% was applicable for use as internal standards in the drug clinical study.

A simple method for α-position deuterated carbonyl compounds with pyrrolidine as catalyst

A simple, cost-effective method for deuteration of carbonyl compounds employing pyrrolidine as catalyst and D2O as deuterium source was described. High degree of deuterium incorporation (up to 99%) and extensive functional group tolerance were achieved. It is the first time that secondary amines are used as catalysts for H/D exchange of carbonyl compounds, which also allow the deuteration of complex pharmaceutically interesting substrates. A possible catalytic mechanism, based on the hydrolysis of 1-pyrrolidino-1-cyclohexene, for this pyrrolidine-catalyzed H/D exchange reaction has been proposed.

The renaissance of H/D exchange

The increasing demand for stable isotopically labeled compounds has led to an increased interest in H/D-exchange reactions at carbon centers. Today deuterium-labeled compounds are used as internal standards in mass spectrometry or to help elucidate mechanistic theories. Access to these deuterated compounds takes place significantly more efficiently and more cost effectively by exchange of hydrogen by deuterium in the target molecule than by classical synthesis. This Review will concentrate on the preparative application of the H/D-exchange reaction in the preparation of deuterium-labeled compounds. Advances over the last ten years are brought together and critically evaluated.

Triazabicyclodecene: An Effective Isotope Exchange Catalyst in CDCl3

We describe the first effective H/D exchange reaction with acidic substrates in CDCl(3) at room temperature. The particularly mild reaction conditions involved (solvent, base, and temperature) allow the chemoselective deuteration of ketones over esters. An NMR study was conducted with the aim of rationalizing the results obtained in the presence of TBD as catalyst.