open access

https://hdl.handle.net/2115/91030

Toward calix[2]-type macrocycles: Synthesis and structural analysis of cyclic tetraketone and highly strained furanophane

英語

polyketone

2023-07

World Scientific Publishing

Journal of porphyrins and phthalocyanines

27(07n10)

1067-1073

Recent progress in the synthesis of calix[3]pyrrole has proven that cyclic polyketones composed of 3,3-dialkylated pentane-2,4-diones as the repeating unit are promising precursors for strained calix-type macrocycles. Toward the synthesis of calix[2]pyrrole and calix[2]furan, which are the most strained congeners among the possible calix[n]pyrroles and calix[n]furans, we report the synthesis of a cyclic dimer of 3,3-dimethylpentane-2,4-dione and its furanophane derivative. These compounds were produced from a linear tetraketone precursor. Single crystal X-ray diffraction analysis revealed that the furan ring in the furanophane was highly strained with deformation angles alpha and beta of 3.69 degrees and 16.00 degrees, respectively. These deformation angles were the largest in the series of 1,4-diketone-linked oligofuran macrocycles. Although these two macrocyclic compounds are likely the most promising precursors for calix[2]-type macrocycles, Paal-Knorr-type pyrrole or furan ring formation did not proceed under standard conditions used for calix[3]pyrrole or calix[3]furan. Theoretical calculations indicated that the second aromatic ring formation on the cyclic tetraketone is a highly uphill process whose activation energy cannot be overcome by standard thermal reactions.

学術雑誌論文

Accepted Manuscript

Electronic version of an article published as Journal of Porphyrins and Phthalocyanines, Vol. 27, No. 07n10, pp. 1067-1073 (2023), 10.1142/S1088424623500189, copyright© World Scientific Publishing Company, https://doi.org/10.1142/S1088424623500189

1088-4246