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NaBH4-TMEDA and a palladium catalyst as efficient regio- and chemoselective system for the hydrodehalogenation of halogenated heterocycles

Chelucci, Giorgio Adolfo and Figus, Susanna (2014) NaBH4-TMEDA and a palladium catalyst as efficient regio- and chemoselective system for the hydrodehalogenation of halogenated heterocycles. Journal of Molecular Catalysis A. Chemical, Vol. 393 , p. 191-209. ISSN 1381-1169. Article.

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DOI: 10.1016/j.molcata.2014.06.012

Abstract

The pair NaBH4-TMEDA as hydride source and a palladium catalyst in THF prove to be an efficient system for the hydrodehalogenation of halogenated heterocycles with one or more heteroatoms. In general, Pd(OAc) 2-PPh3 rapidly hydrodehalogenates reactive halo-heterocycles such as bromo-pyridines, -quinolines, -thiophenes, -indoles, -imidazoles, etc., at room temperature in very good yields, whereas in most cases PdCl2(dppf) reduces less reactive halides such as chloro-pyridines, -quinolines, -pyrimidines and bromo-indoles, -benzofurans, etc. Moreover, PdCl2(tbpf) shows to be even more active removing the 2- and 5-chlorine from both thiophene and thiazole rings. The reaction conditions tolerate various functional groups, allowing highly chemoselective reactions in the presence of halide, ester, alkyne, alkene and nitrile substituents. Moreover, with a proper selection of the catalyst it is also possible to obtain a good control in the regioselective hydrodehalogenation of a variety of polyhalogenated substrates.

Item Type:Article
ID Code:9995
Status:Published
Refereed:Yes
Uncontrolled Keywords:Hydrodehalogenation, reduction, haloheterocycles, palladium catalysts, sodium borohydride, N,N,N′,N′-tetramethylethylenediamine
Subjects:Area 03 - Scienze chimiche > CHIM/06 Chimica organica
Divisions:001 Università di Sassari > 01-a Nuovi Dipartimenti dal 2012 > Agraria
Publisher:Elsevier Science
ISSN:1381-1169
Deposited On:01 Aug 2014 09:40

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