Browsing by Author "Thummanagoti, Suman"

Now showing 1 - 4 of 4

Diversity-Oriented Synthesis of Angular Bis-benzimidazole Derivatives under Microwave Irradiation
(2009-11-01)
Chen, Chih-Hau
;
Chien, Ming-Hsien
;
Kuo, Min-Liang
;
Chou, Cheng-Ting
;
Lai, Jin-Ji
Pharmaceutically interesting, angular bis-benzimidazoles with three appendages have been synthesized successfully through a diversity-oriented approach with soluble support under microwave irradiation. Polymer immobilized o-phenylenediamine was selectively N-acylated with 2-chloro-3-nitrobenzoic acid in a primary aromatic amino moiety. The obtained amide was cyclized to benzimidazole in an acidic condition, and subsequently nucleophilic aromatic substitution with different amines was performed. Successive reduction, cyclization with various aldehydes and activated isothiocyanates yielded angular biheterocyclic benzimidazoles in good quantities. Reaction progress on polymer support was precisely monitored using the conventional proton NMR spectroscopy. Preliminary screening results showed some of these interesting compounds exhibited moderately to good inhibition against vascular endothelial growth factor receptor 3 (VEGFR-3), which is related to invasion and migration of cancer cells.
Ionic liquid supported multistep divergent synthesis of benzimidazole linked pyrrolo-/pyrido-/isoindolo-benzimidazolones
(2011-06-01)
Thummanagoti, Suman
;
Yellol, Gorakh S.
;
Sun, Chung-Ming
;
應用化學系
;
Department of Applied Chemistry
Diversity oriented parallel synthesis for bis-heterocyclic skeletal novel benzimidazole linked pyrrolo-/pyrido-benzimidazolones and benzimidazole linked isoindolo-benzimidazolones has been developed on ionic liquid support under microwave irradiation by utilizing the cascade cyclization. The key tandem transformation comprises (i) amino-alkylation of immobilized o-phenylenediamine with ketoacids, (ii) intramolecular cyclization through secondary amine on electrophilic imine carbon toward pentacyclic aza-ring and (iii) second amido-cyclization to deliver cycloamide ring. The synergy arises by combined use of microwave heating with ionic liquid support which is very effectively used to speed up multistep synthesis of biological interesting heterocycles. (C) 2011 Elsevier Ltd. All rights reserved.
Microwave-Assisted Tandem Transformation on an Ionic-Liquid Support: Efficient Synthesis of Pyrrolo/Pyridobenzimidazolones and Isoindolinone-Fused Benzimidazoles
(2011-09-05)
Thummanagoti, Suman
;
Yellol, Gorakh S.
;
Sun, Chung-Ming
;
應用化學系
;
Department of Applied Chemistry
A tandem transformation that involves the formation of three bonds and two heterocyclic rings in a one-pot fashion through amino-alkylation of an ionic-liquid-immobilized diamine with keto acids followed by successive double intramolecular cyclizations to afford a tricyclic framework has been explored. This tandem cyclization has been utilized to develop a rapid and efficient method to synthesize various pyrrolo[1,2-a]benzimidazolones and pyrido[1,2-a]benzimidazolones on an ionic-liquid support by using focused microwave irradiation. The application of this tandem cyclization was further extended to the aromatic keto acids to provide isoindolinone-fused benzimidazoles, a structurally heterogeneous library with skeletal diversity. The outcome of the cascade reaction was confirmed by the X-ray crystallographic study of the product directly attached to the ionic-liquid support. Use of the ionic liquid as a soluble support facilitates purification by simple precipitation along with advantages like high loading capacity, homogeneous reaction conditions, and monitoring of the reaction progress by regular conventional spectroscopic methods, whereas application of microwave irradiation greatly accelerates the rate of the reactions.
Scaffold-directed and traceless synthesis of tricyclic quinoxalinone imidazoles under microwave irradiation
(2011-02-01)
Thummanagoti, Suman
;
Chen, Chih-Hau
;
Xu, Zhan-Hui
;
Sun, Chung-Ming
;
應用化學系
Traceless synthesis of 2-aminoimidazoquinoxalinones has been performed on soluble polymer support under open-vessel microwave dielectric heating. The reaction progression is monitored directly by the conventional proton NMR which indicated no release of the substrate from the support. Fmoc-deprotected amino acid polymer conjugates react with 1,5-difluoro-2,4-dinitro benzene to yield polymer bound dinitro fluoro amines, which are further substituted by various primary amines to yield PEG-immobilized dinitrodiamines. Simultaneous reduction of aromatic meta-dinitro group leads to the traceless release of 2-quinoxalinones, followed by N-hetero cyclization with various isothiocyanates in the presence of mercury(II)chloride to furnish 2-aminoimidazoquinolinone rings with three points of diversity at rapid pace.