a
Institut für Chemie, Universität Hohenheim, Garbenstraße 30, 70599 Stuttgart, Germany
› Author AffiliationsWe would like to acknowledge funding from the Deutsche Forschungsgemeinschaft (DFG) for the 600 MHz NMR instrument used for this study (Grant: INST 36/170-1 FUGG). M.A.S. is grateful to Deutscher Akademischer Austauschdienst (DAAD) for financial support [Research Grants - Doctoral Programmes in Germany, 2019/20 (57440921)].
Dedicated to Professor Hiriyakkanavar Ila on the occasion of her 80th birthday
Abstract
An efficient urease-catalyzed approach for the synthesis of highly substituted 6-amino-4H-pyran-3-carbonitriles based on the formation of three bonds in one step is developed. This unprecedented three-component reaction between one molecule of an aromatic aldehyde and two molecules of an aroylacetonitrile proceeds by employing commercially available urease from jack bean (Canavalia ensiformis) as the catalyst in water at 65 °C to deliver the desired 4H-pyrans in yields of up to 92%. The transformation is proposed to occur via a domino Knoevenagel condensation/1,4-addition/O-cyclization/tautomerization sequence, providing a practical and sustainable approach to 6-amino-4H-pyran-3-carbonitriles from commercially available substrates. Full and unambiguous structural elucidation of all the products is achieved by means of NMR spectroscopy and X-ray crystal structure analysis.
46 CCDC 2357923 contains the supplementary crystallographic data for this paper. The data can be obtained free of charge from The Cambridge Crystallographic Data Centre via www.ccdc.cam.ac.uk/structures