Please use this identifier to cite or link to this item: http://lib.jncasr.ac.in:8080/jspui/handle/10572/2205
Title: One-Pot Synthesis of 2,4,5-Trisubstituted Imidazoles via [2+2+1] Cycloannulation of 1,3-Bishet(aryl)-monothio-1,3-diketones, alpha-Substituted Methylamines and Sodium Nitrite through alpha-Nitrosation of Enaminones
Authors: Yugandar, S.
Konda, S.
Parameshwarappa, G.
Ila, H.
Keywords: Chemistry
Diversity-Oriented Synthesis
Oxidative Coupling Reaction
Bond-Forming Reactions
Hetero-Fused Analogs
Tetrasubstituted Imidazoles
Multicomponent Synthesis
1,2,4,5-Tetrasubstituted Imidazoles
Complementary Regioselectivity
Trisubstituted Imidazoles
Multisubstituted Indoles
Issue Date: 2016
Publisher: American Chemical Society
Citation: Yugandar, S.; Konda, S.; Parameshwarappa, G.; Ila, H., One-Pot Synthesis of 2,4,5-Trisubstituted Imidazoles via 2+2+1 Cycloannulation of 1,3-Bishet(aryl)-monothio-1,3-diketones, alpha-Substituted Methylamines and Sodium Nitrite through alpha-Nitrosation of Enaminones. Journal of Organic Chemistry 2016, 81 (13), 5606-5622 http://dx.doi.org/10.1021/acs.joc.6b00938
Journal of Organic Chemistry
81
13
Abstract: An efficient one-pot synthesis of a series of diversely functionalized trisubstituted 4(5)het(aroyl)-2,5(4)-het(aryl)/alkylimidazoles from readily available 1,3-bishet(aryl)monothio-1,3-diketones has been reported. This novel sequential one-pot, three step protocol, wherein three new carbon nitrogen bonds are formed in contiguous fashion, involves in situ generation of enaminones by reaction of monothio-1,3-diketones with alpha-substituted methylamines, followed by their alpha-nitrosation with sodium nitrite and subsequent base mediated intramolecular heterocyclization of the resulting alpha-hydroxyiminoimines to trisubstituted imidazoles in high yields under mild conditions. These newly prepared 4(5)-het(aroyl)-5(4)-het(aryl)/alkylimidazoles are shown to exist as tautomeric mixture, however, their subsequent alkylation with methyl iodide in the presence of potassium carbonate affords 1-N-methy-2,5-bishet(aryl)-4-het(aroyl)imidazoles in highly regioselective fashion in most of the cases. Synthesis of few 4(5)-(2-hydroxyphenyl)-2,5(4)-substituted imidazoles, which are known to be good coordinating ligands, has also been reported. A probable mechanism for the formation of these imidazoles from hydroxyiminoimine intermediates has also been suggested.
Description: Restricted Access
URI: http://hdl.handle.net/10572/2205
ISSN: 0022-3263
Appears in Collections:Research Papers (H. Ila)

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