標題: Regioselective, Unconventional Pictet-Spengler Cyclization Strategy Toward the Synthesis of Benzimidazole-Linked Imidazoquinoxalines on a Soluble Polymer Support
作者: Chen, Chih-Hau
Kuo, Jaren
Yellol, Gorakh S.
Sun, Chung-Ming
應用化學系
Department of Applied Chemistry
關鍵字: diversity-oriented synthesis;heterocycles;microwave chemistry;Pictet-Spengler cyclization;solid-phase synthesis
公開日期: 6-六月-2011
摘要: A novel strategy for an unconventional Pictet-Spengler reaction has been developed for the regioselective cyclization of the imidazole ring system at the C2 position. The developed strategy was utilized to develop a diversity-oriented parallel synthesis for bis(heterocyclic) skeletal novel analogs of benzimidazole-linked imidazoquinoxalines on a soluble polymer support under microwave conditions. Condensation of polymer-immobilized o-phenylenediamines with 4-fluoro-3-nitrobenzoic acid followed by nucleophilic aromatic substitution with an imidazole motif affords bis(heterocyclic) skeletal precursors for the Pictet-Spengler reaction. The unconventional Pictet-Spengler cyclization with various aldehydes was achieved regioselectively at the C2 position of the imidazole ring to furnish rare imidazole-fused quinoxaline skeletons. During the Pictet-Spengler cyclization, aldehydes bearing electron-donating groups afford 4,5-dihydro-imidazoquinoxalines, which then auto-aromatize into benzimidazole-linked imidazo[1,2-a]quinoxalines. However, interestingly, aldehydes bearing electron-withdrawing groups directly provide aromatized imidazo[1,2-a]quinoxalines, which unexpectedly afford novel benzimidazole-linked 4-methoxy-4,5-dihydro-imidazo[1,2-a] quinoxalines after polymer cleavage.
URI: http://dx.doi.org/10.1002/asia.201000913
http://hdl.handle.net/11536/22758
ISSN: 1861-4728
DOI: 10.1002/asia.201000913
期刊: CHEMISTRY-AN ASIAN JOURNAL
Volume: 6
Issue: 6
起始頁: 1557
結束頁: 1565
顯示於類別:期刊論文


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  1. 000292097700038.pdf