Diels-Alder reaction of 1-methylcycloprop-2-ene-1-carbonitrile with methyl 2-Oxo-2H-pyran-5-carboxylate

Article abstract of DOI:10.1134/S1070428006070074

The Diels-Alder reaction of 1-methylcycloprop-2-ene-1-carbonitrile and coumalic acid methyl ester (methyl 2-oxo-2H-pyran-5-carboxylate) gave a 2:1 adduct with endo-syn configuration of both cyclopropane fragments, which was established by X-ray analysis. According to the ¹H NMR data, the reaction involves intermediate formation of decarboxylated 1:1 adduct having a cycloheptatriene structure; its isomerization into the corresponding caradiene, followed by addition of the second dienophile molecule, was confirmed by quantum-chemical calculations. Pleiades Publishing, Inc., 2006.