Polytopal Rearrangement Governing Stereochemistry of Bicyclic Oxime Ether Synthesis (CROSBI ID 315544)
Prilog u časopisu | izvorni znanstveni rad | međunarodna recenzija
Podaci o odgovornosti
Spahić, Zlatan ; Hrenar, Tomica ; Primožič, Ines
engleski
Polytopal Rearrangement Governing Stereochemistry of Bicyclic Oxime Ether Synthesis
In the present study, four O-substituted oximes of quinuclidin-3-one were synthesized using appropriate O-substituted hydroxylamine hydrochlorides. In order to perform these reactions in a solvent, a mixture of (E) and (Z) products was yielded. Using mechanochemical and microwave synthesis, we then obtained pure (E) oximes. In almost all cases, the conversion to oxime ethers was completed. Reactions were monitored by ATR spectroscopy and the ratios of (E) and (Z) oxime ethers were deduced from 1H NMR data. Several reactions were very rapid (1 min) with 100% conversion and stereospecificity. To investigate the reaction mechanisms, full conformational analyses of the reaction intermediates were performed and the lowest energy conformers were determined. These conformers differed in spatial arrangement around the nitrogen atom of the amino group and were in the correct orientation for reactions to occur. Calculated standard Gibbs energies of the formation were in agreement with the experimentally obtained ratios of (E) and (Z) isomers. This work shows alternatives to the classical synthesis of O-substituted oxime ether precursors and highlights the fast reaction rate and stereoselectivity of microwave synthesis as well as the “green” aspects of mechanochemistry.
O-substituted ketoximes ; stereoselectivity ; mechanochemical and microwave synthesis ; conformational analysis
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Podaci o izdanju
23 (20)
2022.
12331
14
objavljeno
1422-0067
10.3390/ijms232012331