One-pot synthesis of highly diversified tetrahydropyridines by tandem condensation of aldehydes, amines, and β-ketoesters

Silica-supported boron trifluoride (BF3 center dot SiO2) was used as an efficient and reusable catalyst for the synthesis of highly diversified tetrahydropyridines by one-pot multicomponent reactions of amines and aldehydes with beta-ketoester. This method proceeds through the intermolecular Mannich reaction followed by intramolecular Mannich reaction. The observed hydrogen bonding interaction was studied in detail with single crystal X-ray diffraction analysis and Etter's graph. Finally, this method has the advantage of easy work-up, convenient, relatively short reaction times and the products were isolated with high yields. (C) 2011 Elsevier Ltd. All rights reserved.