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Browsing by Author "Sun, Mei-Lian"

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    Microwave assisted straightforward synthetic method for benzimidazole linked quinoxalinones on soluble polymer support
    (2011-03-18)
    Chou, Cheng-Ting
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    Yellol, Gorakh S.
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    Chang, Wong-Jin
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    Sun, Mei-Lian
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    Sun, Chung-Ming
    The simple and efficient method was developed for the synthesis of benzimidazole linked quinoxalinones on soluble polymer support using microwave conditions. The acid catalyzed condensation of 4-fluoro-3-nitrobenzoic acid with polymer immobilized o-phenylenediamine, ipso-fluoro nucleophilic substitution with various primary amines and cyclization with acetyl chloride are the key steps involved in implemented linear synthesis. In key cyclization step, the regioselective N-acylation at secondary amine with chloroacetyl chloride followed by spontaneous intramolecular ring closure through ortho-amine functionality generate the quinoxaline skeleton under microwave irradiation. The removal of polymer support and exposure of quinoxalines for auto-oxidation finally produce the benzimidazole linked quinoxalinone derivatives with high purity and yields. (C) 2011 Elsevier Ltd. All rights reserved.
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    Microwave-assisted traceless synthesis of hydantion-fused beta-carboline scaffold
    (2007-11-26)
    Yeh, Wen-Pin
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    Chang, Wong-Jin
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    Sun, Mei-Lian
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    Sun, Chung-Ming
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    應用化學系
    Multistep microwave-assisted reactions toward the synthesis of hydantoin-fused tricyclic tetrahydro-beta-carbolines on the soluble polymer support have been developed. Polymer-bound tryptophan with various aldehydes has been subjected to Pictet-Spengler reaction to obtain tricyclic beta-carboline conjugates. The terminal hydantoinyl moiety is constructed across polymer-bound beta-carbolines by the reaction with various isocyanates under microwave irradiation to form urea intermediate. Simultaneous intramolecular cyclization of urea followed by cleavage of the polymer support leads to a traceless synthesis of tetracyclic scaffolds in high yield and high purity. (c) 2007 Elsevier Ltd. All rights reserved.