Reaction of quinaldine with 4,6-di(tert-butyl)-3-nitro-1,2-benzoquinone. Dependence of the outcome on the reaction conditions and a deeper insight into the mechanism

Tatyana A Krasnikova; Yurii A Sayapin; Inna O Tupaeva; Eugeny A Gusakov; Ilya V Ozhogin; Anton V Lisovin; Mikhail V Nikogosov; Oleg P Demidov; Duong Nghia Bang; Tran Dai Lam; Nguyen Thi Thu Trang; Alexander D Dubonosov; Vladimir I Minkin

doi:10.1016/j.heliyon.2023.e16943

Reaction of quinaldine with 4,6-di(tert-butyl)-3-nitro-1,2-benzoquinone. Dependence of the outcome on the reaction conditions and a deeper insight into the mechanism

Heliyon. 2023 Jun 7;9(6):e16943. doi: 10.1016/j.heliyon.2023.e16943. eCollection 2023 Jun.

Affiliations

¹ Institute of Physical and Organic Chemistry, Southern Federal University, Rostov on Don 344090, Russian Federation.
² Federal Research Centre the Southern Scientific Centre of the Russian Academy of Sciences, Rostov on Don 344006, Russian Federation.
³ North Caucasus Federal University, Stavropol 355009, Russian Federation.
⁴ Office of the State Council for Professorship, Ministry of Education and Training, Hanoi, 10000, Viet Nam.
⁵ Institute for Tropical Technology, Vietnam Academy of Science and Technology, Hanoi, 10000, Viet Nam.

Abstract

Condensation of quinaldine with 4,6-di (tert-butyl)-3-nitro-1,2-benzoquinone results in the formation of 5,7-di (tert-butyl)-2-(quinoline-2-yl)-1,3-tropolone, 5,7-di (tert-butyl)-4-nitro-2-(quinoline-2-yl)-1,3-tropolone, 3,3-dimethyl-2-(5-hydroxy-4-nitro-3-tert-butyl-6-quinoline-2-yl-pyridine-2-yl)butanoic acid, 6-(2,2-dimethylprop-3-yl)-5-tert-butyl-4-nitro-2-(quinoline-2-yl)-pyridine-3-ol, 1,7-di (tert-butyl)-3-(quinoline-2-yl)-2-azabicyclo-[3.3.0]octa-2,7-diene-4,6-dione-N-oxide. The formation of 1,3-tropolone and pyridine-2-yl butanoic acid derivatives proceeds through a ring expansion and 2-azabicyclo [3.3.0]octa-2,7-diene-4,6-dione-N-oxide via the contraction of the o-quinone ring. The structure of the heterocyclic compounds obtained was justified by X-ray diffraction analysis, NMR spectroscopy, IR- and HRMS-spectrometry, and the proposed mechanisms of their formation include the participation of an intermediate product of the expansion reaction of the o-quinone cycle - 5,7-di (tert-butyl)-4-nitro-2-(quinoline-2-yl)-cyclohepta-1,3,5-triene-1,3-diol, which was first isolated preparatively. The DFT/B3LYP/6-311++G** methods were used to determine the thermodynamic stability of tautomeric forms of intermediate products, as well as the relative stability of NH and OH tautomers of 5,7-di (tert-butyl)-2-(quinolin-2-yl)-1,3-tropolone and 5,7-di (tert-butyl)-4-nitro-2-(quinolin-2-yl)-1,3-tropolone.

Keywords: 1,3-Tropolones; 4,6-Di(tert-butyl)-3-nitro-1,2-benzoquinone; Contraction of the o-quinone ring; DFT; X-ray spectroscopy; o-Quinone ring expansion.