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Multicomponent Cyanation of 2-Amino-3-cyano-4H-chromenes in Aqueous Media, Ardevines, S.; Garcés-Marín, M.; Cervantes-Cerrada, P.; Aamir, S.; Herrera, R. P.; Marqués-López, E. Asian J. Org. Chem. 2024, e202400443, early view. DOI: 10.1002/ajoc.202400443.
Abstract. Chromenes represent a pivotal molecular structure found in a diverse range of biologically active compounds. Specifically, derivatives of 2-amino-3-cyano-4H-chromene have demonstrated pharmacological applications, displaying potential antioxidant and anticancer activities. This has heightened interest in the exploration of new and more efficient methods for their synthesis. In recent years, few examples have emerged, focusing on the organocatalytic and enantioselective synthesis of 2-amino-3-cyano-4H-chromene derivatives, although the overall number of works to date is limited. In this study, we present the results of the synthesis of 2-amino-4H-chromen-3,4-dicarbonitriles through a Michael addition of cyanide to 2-iminochromenes. To achieve this, we utilized a mild source of cyanide (acetone cyanohydrin), green solvents and catalytic conditions at room temperature, via a multicomponent approach. Furthermore, we initiated the enantioselective study of this process using chiral organocatalysts obtaining promising preliminary results.
C bond formation reactions. These DESs serve as both organocatalysts and reaction media in the aldol reaction, reducing the need for additional toxic or hazardous chemicals. By employing these DESs, we were able to activate the desired reaction through the condensation of ketones and L-proline via enamine activation. This approach eliminates the requirement for traditional, often environmentally harmful, organic solvents. Notably, diethylene glycol played a crucial role in modulating the reaction performance, including conversion and enantioselectivity. Diethylene glycol is a relatively safer alternative compared to other commonly used solvents or additives with potential environmental and health risks. Moreover, reducing the L-proline content in the DESs led to a slight increase in the enantiomeric excess of the predominant diastereomeric product. This finding suggests the possibility of minimizing the use of L-proline, which can be advantageous from both cost and environmental perspectives.
Herrera-OrganoCatalisis Asimétrica Group 