Synthesis of 4-oxo-6-styryl-4H-pyran-2-carbonitriles and their application for the construction of new 4-pyrone derivatives

Synthesis of 2-cyano-6-styryl-4-pyrones has been developed on the basis of 6-metylcomanic acid via modifications of the methyl and carboxyl groups. Reactions of these pyrones with nucleophiles proceeded as an attack at the cyano group, whereas 1,3-dipolar cycloaddition of stabilized azomethine ylides occurred at the styryl moiety stereo- and regioselectively. The effective approach based on the side chain manipulation of the 2-cyano-6-styryl-4-pyrones led to 2-azolyl-6-styryl-4-pyrones and 4-pyrone conjugates with the pyrrolidine moiety. Reactivity of the prepared 2-cyano-6-styryl-4-pyrones was estimated with the use of quantum chemical calculations, and the observed chemoselectivity was explained by charge and orbital controls. The photophysical properties of the cyanopyrones were determined in view of further application as simple molecular fluorophores with large Stokes shifts.

Automated summary

A synthesis method for 2-cyano-6-styryl-4-pyrones has been developed through modifications of the methyl and carboxyl groups of 6-metylcomanic acid. These pyrones react with nucleophiles at the cyano group and undergo 1,3-dipolar cycloaddition at the styryl moiety with stereo- and regioselectivity. The synthesized compounds show potential as molecular fluorophores with large Stokes shifts.