Next Article in Journal
Microwave Assisted Facile Cleavage of 2,4-Dinitrophenylhydrazones to the Corresponding Carbonyl Compounds with N,N′-Dibromo-N,N′-1,2-ethanediylbis(p-toluenesulphonamide)
Previous Article in Journal
Synthesis of “Acetylene-Expanded” Tridentate Ligands
Article Menu

Export Article

Open AccessArticle
Molecules 2002, 7(5), 456-464; https://doi.org/10.3390/70500456

Niobium Pentachloride Activation of Enone Derivatives: Diels-Alder and Conjugate Addition Products

Departamento de Química, Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, Universidade de São Paulo, Av. Bandeirantes 3900, 14040-901 – Ribeirão Preto – SP, Brazil
*
Author to whom correspondence should be addressed.
Received: 19 March 2002 / Revised: 15 May 2002 / Accepted: 17 May 2002 / Published: 31 May 2002
Full-Text   |   PDF [45 KB, uploaded 18 June 2014]   |  

Abstract

Niobium pentachloride has proven to be a powerful activating agent for Diels-Alder or conjugate addition reactions of cycloenones. The Diels-Alder product was obtained only with an unsubstituted enone (cyclohexenone) and the highly reactive diene cyclopentadiene; substituents in the b-position of enones seem to prevent Diels-Alder reaction: oxygenated substituents favor the formation of vinyl chlorides (ethyl ether or dichloromethane as solvents) or enol ethers (ethyl acetate as solvent), while a methyl substituent prevents any kind of transformation with NbCl5. Less reactive dienes, furan and 2-methylfuran gave the conjugate addition products of the furan ring to the enone system. View Full-Text
Keywords: Niobium pentachloride; Lewis acid; Diels-Alder reaction; vinyl chlorides Niobium pentachloride; Lewis acid; Diels-Alder reaction; vinyl chlorides
Figures

Figure 1

This is an open access article distributed under the Creative Commons Attribution License (CC BY 3.0).
SciFeed

Share & Cite This Article

MDPI and ACS Style

Constantino, M.G.; Júnior, V.L.; Da Silva, G.V.J. Niobium Pentachloride Activation of Enone Derivatives: Diels-Alder and Conjugate Addition Products. Molecules 2002, 7, 456-464.

Show more citation formats Show less citations formats

Related Articles

Article Metrics

Article Access Statistics

1

Comments

[Return to top]
Molecules EISSN 1420-3049 Published by MDPI AG, Basel, Switzerland RSS E-Mail Table of Contents Alert
Back to Top