Work

A Photo-Smiles Rearrangement: Mechanistic Investigation of the Formation of Blatter Radical Helicenes

Year: 2025

Type: article

Abstract: High Resolution Image Download MS PowerPoint Slide Photocyclization of 8-aryloxy-3-phenylbenzo[ e ][1,2,4]triazines leads to helicene radicals. Structural analysis of radicals leuco forms by two-dimensional correlation nuclear magnetic resonance methods demonstrated that the photocyclization involves a Smiles rearrangement and exclusive formation of a single rearranged product for all substrates. Density functional theory investigations indicate that the mechanism requires the T 1 state with (n, π*) character localized on the benzo[ e ][1,2,4]triazine (BT) fragment and at least one occupied π molecular orbital (MO) localized on the aryloxy fragment with an energy that is higher than that of the n MO. This electronic structure is favorable for aryl-to-BT single-electron transfer and formation of a zwitterion, which undergoes an intramolecular polar cyclization followed by ring opening of the resulting spirooxazole. The proposed mechanism represents a new variation of photo-Smiles rearrangement and appears to be general for the photochemical formation of planar Blatter radicals.

Source: The Journal of Organic Chemistry

DOI: 10.1021/acs.joc.4c02893

Authors: Hemant K. Singh, Sławomir Kaźmierski, Piotr Kaszyński

Institutions: Centrum Badań Molekularnych i Makromolekularnych Polskiej Akademii Nauk, Polish Academy of Sciences, Middle Tennessee State University, University of Łódź

Language: English

Topic: Synthesis and Properties of Aromatic Compounds

Subfield: Organic Chemistry

Field: Chemistry

Domain: Physical Sciences

Open Access status: hybrid

Estimated APC paid: $4,500

Funder: Narodowe Centrum Nauki