Imine-Based Catechols and o-Benzoquinones: Synthesis, Structure, and Features of Redox Behavior

Tatiana V Astaf'eva; Maxim V Arsenyev; Roman V Rumyantcev; Georgy K Fukin; Vladimir K Cherkasov; Andrey I Poddel'sky

doi:10.1021/acsomega.0c02277

Imine-Based Catechols and o-Benzoquinones: Synthesis, Structure, and Features of Redox Behavior

ACS Omega. 2020 Aug 21;5(35):22179-22191. doi: 10.1021/acsomega.0c02277. eCollection 2020 Sep 8.

Authors

Tatiana V Astaf'eva^{1

2}, Maxim V Arsenyev^{1

2}, Roman V Rumyantcev¹, Georgy K Fukin¹, Vladimir K Cherkasov^{1

2}, Andrey I Poddel'sky¹

Affiliations

¹ G.A. Razuvaev Institute of Organometallic Chemistry, Russian Academy of Sciences, 49 Tropinina str., Nizhniy Novgorod 603137, Russian Federation.
² Chemical Faculty, National Research Lobachevsky State University of Nizhny Novgorod, 23 Gagarina av., Nizhniy Novgorod 603950, Russian Federation.

Abstract

Novel sterically hindered catechols of the type 3-(RN=CH)-4,6-DBCatH₂ with iminoalkyl or iminoaryl groups in the third position of the aromatic ring have been synthesized and characterized in detail. The o-benzoquinones 3-(RN=CH)-4,6-DBBQ have been synthesized by the oxidation of the corresponding catechols. The oxidation of methylimino-substituted catechol with K₃[Fe(CN)₆] in alkaline medium leads to the formation of two products: o-quinone and diene-dione, the product of the water addition to the corresponding o-quinone. Some o-benzoquinones react with water or methanol to yield products of water or methanol addition. A prototropic tautomerism is characteristic of catecholaldimines: a quinomethide form is observed in the case of aliphatic amine derivatives, while aryl-substituted catecholaldimines can exist both in the catechol and quinomethide forms in the crystalline state. The formation of dimeric structures motifs is observed in crystals. The electrochemical oxidation of imino-based catechols proceeds via two one-electron processes; the second wave is quasi-reversible, which is unusual for catechols.