Duality of Reactivity of a Biradicaloid Compound with an o-Quinodimethane Scaffold

Sahara, Keisuke; Abe, Manabu; Zipse, Hendrik und Kubo, Takashi (2020): Duality of Reactivity of a Biradicaloid Compound with an o-Quinodimethane Scaffold. In: Journal of the American Chemical Society, Vol. 142, No. 11: pp. 5408-5418

Abstract

Sigmarene, which is a Kekule hydrocarbon with appreciable singlet biradical character originating from an o-quinodimethane scaffold, is isolated as a doubly sigma-bonded dimer. The dimer dissociates into a monomeric sigmarene upon heating or photoirradiation. The monomeric species undergoes a rapid [4 + 4] cycloaddition reaction under dark conditions even at room temperature to produce the dimer. Contrarily, the monomeric sigmarene undergoes a [4 + 2] cycloaddition reaction in the presence of dienophile as an orbital symmetry allowed process. Therefore, the sigmarene shows high reactivity for both symmetry-forbidden and allowed processes in the framework of the orbital symmetry rule. This duality of reactivity of the sigmarene is consistent with the intermediate singlet biradical character (44%) estimated by a density functional theory (DFT) calculation.

• Item Type: Journal article
• Faculties: Chemistry and Pharmacy > Department of Chemistry
• Subjects: 500 Science > 540 Chemistry
• ISSN: 0002-7863
• Language: English