Hydrogen Isotope Labeling\nof Pharmaceuticals Via Dual\nHydrogen Isotope Exchange Pathways Using CdS Quantum Dot Photocatalyst

Isotopic labeling is a powerful technique extensively\nused in the\npharmaceutical industry. By tracking isotope-labeled molecules, researchers\ngain unique and invaluable insights into the pharmacokinetics and\npharmacodynamics of new drug candidates. Hydrogen isotope labeling\nis particularly important as hydrogen is ubiquitous in organic molecules\nin biological systems, and it can be introduced effectively through\nlate-stage hydrogen isotope exchange (HIE). However, hydrogen isotope\nmethods that simultaneously label multiple sites with varying types\nof C–H bonds in the different types of molecules are still\nlacking. Herein, we demonstrate a heterogeneous photocatalytic system\nusing a CdS quantum dot catalyst that proceeds via a unique dual HIE\npathway mechanismone occurs in the reaction solution and the\nother on the catalytic surfaceto address it. This unique mechanism\nunlocked several unique labeling capabilities, including simultaneous\nlabeling of multiple and challenging sites such as secondary α-amino,\nα-ethereal, allyl, and vinyl sites, providing great versatility\nin practical uses for pharmaceutical labeling.