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Molecules 2016, 21(11), 1571; doi:10.3390/molecules21111571

A Metal-Free Regioselective Multicomponent Approach for the Synthesis of Free Radical Scavenging Pyrimido-Fused Indazoles and Their Fluorescence Studies

1
Chemistry of Heterocycles & Natural Product Research Laboratory, Department of Chemistry, School of Advanced Sciences, VIT University, Vellore 632014, Tamilnadu, India
2
G Mokesh Rayalu, Department of mathematics, School of Advanced Sciences, VIT University, Vellore 632014, Tamilnadu, India
3
Department of Botany and Microbiology, Addiriyah Chair for Environmental Studies, College of Science, King Saud University, P.O. Box 2455, Riyadh 11451, Saudi Arabia
*
Author to whom correspondence should be addressed.
Academic Editor: Roman Dembinski
Received: 23 September 2016 / Revised: 8 November 2016 / Accepted: 11 November 2016 / Published: 18 November 2016
(This article belongs to the Collection Heterocyclic Compounds)
View Full-Text   |   Download PDF [2326 KB, uploaded 18 November 2016]   |  

Abstract

This study deals with a new and efficient metal-free regioselective synthesis of pyrimido-fused indazoles with nitrogen ring junction motifs. We have developed a metal-free domino type reaction between 3-aminoindazole, aryl aldehydes and aceotophenones in the presence of KOH/DMF that leads to pyrimido[1,2-b]indazole analogues. Response Surface Methodology (RSM) coupled with a Box-Behnken design (BBD) were utilized for exploring the effect of base used (A), temperature of reaction (B) and (C), reaction time. This approach can allow access to a variety of pyrimidoindazole fluorophores and related compounds. The compound N,N-dimethyl-4-(2-phenylpyrimido[1,2-b]indazol-4-yl)aniline (4e) displays the maximum fluorescence intensity at 518 nm and shows a fluorescence quantum yield of 0.068. The synthesized pyramido-fused indazoles have been evaluated for their free radical scavenging activity and compound 4f showed good antioxidant activity. View Full-Text
Keywords: N-fused pyrimidine; Strecker synthesis; A3 coupling; Box-Behnken design (BBD); fluorescence N-fused pyrimidine; Strecker synthesis; A3 coupling; Box-Behnken design (BBD); fluorescence
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This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. (CC BY 4.0).

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Palaniraja, J.; Mohana Roopan, S.; Mokesh Rayalu, G.; Abdullah Al-Dhabi, N.; Valan Arasu, M. A Metal-Free Regioselective Multicomponent Approach for the Synthesis of Free Radical Scavenging Pyrimido-Fused Indazoles and Their Fluorescence Studies. Molecules 2016, 21, 1571.

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