Title of article :
First application of hexaaquaaluminium(III) tetrafluoroborate as a mild, recyclable, non-hygroscopic acid catalyst in organic synthesis: a simple and efficient protocol for the multigram scale synthesis of 3,4-dihydropyrimidinones by Biginelli reaction
Author/Authors :
Mladen Litvi?، نويسنده , , Ivana Ve?enaj، نويسنده , , Zrinka Mikulda? Ladi?i?، نويسنده , , Marija Lovri?، نويسنده , , Vladimir Vinkovi?، نويسنده , , Mirela Filipan-Litvi?، نويسنده ,
Issue Information :
هفته نامه با شماره پیاپی سال 2010
Abstract :
For the first time hexaaquaaluminium(III) tetrafluoroborate has been used as a mild acid catalyst in organic synthesis. A simple method of its preparation based on the reaction of aluminium triisopropoxide and tetrafluoroboric acid in isopropanol afforded catalyst of high purity and activity. The three-component Biginelli condensation of acetoacetate esters, urea and aldehydes catalyzed by 10 mol % of [Al(H2O)6](BF4)3 in refluxing acetonitrile afforded 3,4-dihydropyrimidonones in good to high yields on multigram scales. The tolerance to acid sensitive reactants such as thienyl and furyl carbaldehydes, applicability to sterically hindered β-ketoesters and simple recyclability without losing catalytic activity make this catalyst as good replacement to literature methods. The mechanism of the reaction includes formation of the so called ‘ureido-crotonate’ rather than corresponding acylimino intermediate as found with Brønsted type catalysts.
Keywords :
3 , Biginelli reaction , Heterocycles , Condensation , 4-Dihydropyrimidinone , Hexaaquaaluminium(III) tetrafluoroborate
Journal title :
Tetrahedron
Journal title :
Tetrahedron