Synthesis of Spiro-Bridged 3,4-Dihydrocoumarins Through an Organocatalytic Cascade Sequence Diels-Alder/Nucleophilic Ring Closing
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Updated: Aug 28, 2026

Efficient Construction of Drug-like Bispirocyclic Scaffolds Via Organocatalytic Cycloadditions of α-Imino γ-Lactones and Alkylidene Pyrazolones
Published on: February 7, 2019
Alberto Medina-Ortíz1, José Luis Olivares-Romero2, Alfonso Reyes-Luna1
1Departamento de Química, División de Ciencias Naturales y Exactas, Universidad de Guanajuato, Noria Alta S/N, Guanajuato 36050, Mexico.
Abstract:
3,4-dihydrocoumarins and spiro compounds constitute an important class of privileged frameworks present in a wide variety of natural and synthetic molecules with diverse applications. In this study, we developed an organocatalytic methodology for the construction of complex and diverse chiral spiro-bridged 3,4-dihydrocoumarins through a Diels-Alder/Nucleophilic ring-closing cascade via trienamine activation. The reaction proceeds efficiently with different trienamine precursors and a range of coumarin-3-carboxamides, which act as both dienophile and intramolecular nucleophile species. This process affords the desired products in good yields and with a high degree of stereocontrol. Furthermore, several transformations on the newly formed spiro-piperidone ring demonstrate the synthetic utility of the obtained compounds.
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The simplest example of a diene is 1,3-butadiene, an acyclic conjugated π system. At room temperature, the molecule exists as a mixture of s-cis and s-trans conformers by virtue of rotation around the carbon–carbon single bond. Although the s-trans isomer is more stable, the...

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