Organocatalytic Diastereoselective Multicomponent Domino Knoevenagel/Diels-Alder Reaction: Synthesis of Densely Functionalized Spiro[5.5]undecane

The domino Knoevenagel/Diels-Alder condensation is a highly efficient strategy for the preparation of heterocyclic compounds. In order to study this reaction with an imine catalyst, a three-component reaction involving aromatic aldehydes, benzylideneacetone and meldrum acid catalyzed by a series of new organocyclic amino acid catalysts was developed. This simple experiment and environmentally friendly method is beneficial for us to get numerous pharmacological multi substituted spiro[5,5]undecane-1,5,9-triones in moderate to good yields (up to 81%) with excellent diastereolectivities (>99:1 dr). Moreover, we expanded the reaction substrates, such as barbituric acid, and the catalytic activity was compared with L-proline that is one of the most commonly secondary amine organocatalysts.