​・Catalytic Site-Selective C–H Oxidation Utilizing Carboxylic Acid Cooperation

  A newly developed Ru(bpga)(H-dicarboxylate)2 complex, featuring dicarboxylate ligands for intramolecular carboxylic acid activation of oxo intermediate, has been identified as a practical oxidation catalyst. This complex demonstrates outstanding environmental adaptability, utilizing hydrogen peroxide (H2O2) as an oxidant. Remarkably, even at catalyst loadings as low as 0.1 to 0.5 mol%, it facilitates high site-selective C–H oxidation of a wide range of substrates, including complex and multifunctional natural products, at impressive reaction rates (TOF = up to 760 /h).

​・Catalytic Oxygen Isotope Labeling Method: C–H Oxidation Using Water as the Oxygen Source

Stable oxygen isotope-labeled compounds are poised as promising probes for emerging bioimaging techniques like secondary ion mass spectrometry (SIMS) and 17-O MRI. However, a significant challenge arises from the substantial requirement of over 500 equivalents of rare and costly labeled water during their synthesis.
In response, we have initiated the development of a novel method utilizing water as the oxygen source for  Ru(bpga)Cl2 catalyzing C–H oxygen functionalization. Remarkably, with a mere 1.0 to 5.0 equivalents of labeled water, we have achieved synthesis of oxygen isotope-labeled compounds with nearly undiminished labeling efficiency. Leveraging this approach, we have successfully attained gram-scale synthesis of labeled sugars.