Unusual spontaneous oxidation of 2,2′-(quinolin-2-ylmethylene)bis(1H-indene-1,3(2H)-dione): An experimental and theoretical study of the mechanism

Mark V. Sigalov, Bagrat A. Shainyan

Research output: Contribution to journalArticlepeer-review

1 Scopus citations

Abstract

2-Quinolinecarbaldehyde reacts with 1,3-indandione to give 2-[(3-hydroxy-1-oxo-1H-inden-2-yl)(quinolin-2-yl)methylene]-1H-indene-1,3(2H)-dione, which is the first example of self-oxidation of the Michael adducts of cycloalkanones with aldehydes. The structure of the product of oxidation is also proved by NMR and elemental analysis of its bromination product 2-[(2-bromo-1,3-dioxo-2,3-dihydro-1H-inden-2-yl)(1,3-dioxo-1,3-dihydro-2H-inden-2-ylidene)-methyl]quinolinium tribromide salt. The mechanism of this unusual reaction is studied experimentally and theoretically in comparison with that of a similar reaction with 2-pyridinecarbaldehyde, which does not lead to self-oxidation. The three-step mechanism includes the formation of a pre-reaction complex, which suffers proton transfer to the pyridinic nitrogen atom, and the hydride ion transfer to the protonated aldehyde. The transition states for the two reactions differ by the position on the reaction coordinate and the heights of the free energy barriers (~25 and ~4 kcal/mol), which allows to explain the observed different reactivity of the two similar hetaryl aldehydes.

Original languageEnglish
Article numbere4410
JournalJournal of Physical Organic Chemistry
Volume35
Issue number12
DOIs
StatePublished - 1 Dec 2022

Keywords

  • 1,3-indandione
  • 2-quinoline carbaldehyde
  • condensation
  • dynamic NMR
  • self-oxidation
  • theoretical calculations

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry
  • Organic Chemistry

Fingerprint

Dive into the research topics of 'Unusual spontaneous oxidation of 2,2′-(quinolin-2-ylmethylene)bis(1H-indene-1,3(2H)-dione): An experimental and theoretical study of the mechanism'. Together they form a unique fingerprint.

Cite this