Modular synthesis of 3-substituted isocoumarins <i>via</i> silver-catalyzed aerobic oxidation/<i>6-endo</i> heterocyclization of <i>ortho</i>-alkynylbenzaldehydes
Hao Wu, Yichun Wang, Andrey Shatskiy, Qiuyan Li, Jian‐Quan Liu, Markus D. Kärkäs, Xiang‐Shan Wang
Abstract
A method involving silver-catalyzed aerobic oxidation/6-endo heterocyclization of ortho-alkynylbenzaldehydes to yield 3-substituted isocoumarins is described. The developed protocol allows convenient access to a range of synthetically useful 3-substituted isocoumarins and related fused heterocyclolactones in good to high yields, using silver tetrafluoroborate as the catalyst, and atmospheric oxygen as the terminal oxidant and the source of endocyclic oxygen. Mechanistic studies suggest the involvement of a free-radical pathway.
Topics & Concepts
IsocoumarinsChemistryCatalysisYield (engineering)Combinatorial chemistryMolecular oxygenOxygenTetrafluoroborateOrganic chemistryIonic liquidMetallurgyMaterials scienceSynthesis and Biological ActivityCatalytic C–H Functionalization MethodsOxidative Organic Chemistry Reactions