Lewis Acid-Catalyzed Chemoselective Reduction of β,γ-Unsaturated-α-Keto Esters with Hantzsch's Ester
Arun K Ghosh1, Tristan John McDonald1
1Department of Chemistry, Department of Medicinal Chemistry and Molecular Pharmacology, Purdue University, West Lafayette, Indiana 47907, United States.
Abstract:
We investigated chemoselective reduction of β,γ-unsaturated α-keto esters with Hantzsch ester in the presence of various Lewis acids. Among conditions surveyed for reduction with Hantzsch ester, stoichiometric TiCl4 (1.05 equiv) provided various keto esters in moderate to good yields (40-72%). However, we examined conditions with various catalytic Lewis acids subsequently. This led to the development of catalytic and chemoselective conditions with as low as 5 mol% FeCl3 in CH2Cl2 at 23 °C to provide α-keto esters in good to excellent yields (78-95%) with good substrate scopes.
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