نتایج جستجو برای: enol tautomerization
تعداد نتایج: 1689 فیلتر نتایج به سال:
The Paternò-Büchi reaction is a photochemical reaction between a carbonyl compound and an alkene to give the corresponding oxetane. In this review the mechanism of the reaction is discussed. On this basis the described use in the reaction with electron rich alkenes (enolethers, enol esters, enol silyl ethers, enanines, heterocyclic compounds has been reported. The stereochemical behavior of the...
Conjugate addition of organometallic reagents to enones to form silyl enol ether products is a versatile method to difunctionalize activated olefins, but the organometallic reagents required can be limiting. The reductive cross-electrophile coupling of unhindered primary alkyl bromides with enones and chlorosilanes to form silyl enol ether products is catalyzed by a nickel-complexed ortho-bromi...
The absorption spectrum of the asymmetric 9-amino-2,7,12,17-tetraphenylporphycene shows new, strongly red-shifted bands compared to the symmetric parental 2,7,12,17-tetraphenylporphycene and to the also asymmetric 9-acetoxy-2,7,12,17-tetraphenylporphycene. Dual emission is also observed with relative contributions that depend strongly on the excitation wavelength and temperature. The gap betwee...
The mechanism of acylation of oxaloacetic acid (OA) with acetyl—CoA was studied at the DFT level using basis functions 6-311G(d,p) and different numbers of diffuse functions. Four mechanisms were considered in this study. It was found that the most probable mechanism, in the approximation of isolated molecules, starts with the enol forms of oxaloacetic acid and acetylcysteamine (final fragment ...
AM1 calculations on equilibrium and transition state geometries of keto and enol forms of glitazones were carried out and compared with those of some carbonyl compounds. The results show that the energy requirements for enolisation of glitazones are much higher than the standard carbonyl systems. Neither the ring system, nor the additional functional groups in thiazolidinedione terminal ring fa...
A new procedure for the stereoselective synthesis of syn α-amino β-oxy ketones is reported. It consists of two steps; in the first step, α-amino silyl enol ethers having a (Z) geometry are prepared from 1-alkynes via 1-sulfonyl-1,2,3-triazoles. In the second step, the silyl enol ethers undergo the TiCl4-mediated Mukaiyama aldol reaction with aldehydes to produce α-amino β-oxy ketones with excel...
This work presents a study on thermo-optical properties of three Schiff bases (imines) in the solid state. The Schiff bases were obtained by means of mechanochemical synthesis using monosubstituted o-hydroxy aromatic aldehydes and monosubstituted aromatic amines. The keto-enol tautomerism and proton transfer via intramolecular O∙∙∙N hydrogen bond of the reported compounds was found to be influe...
Hidden Isomer of Trifluoroacetylacetone Revealed by Matrix Isolation Infrared and Raman Spectroscopy
Enol forms of trifluoroacetylacetone (TFacac) isolated in molecular and rare gas matrices were studied using infrared (IR) Raman spectroscopy. Additionally, calculations DFT B3LYP M06...
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