Lithium Imidazole for the Synthesis of Potential Biological Active Compound

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Title:	Lithium Imidazole for the Synthesis of Potential Biological Active Compound
Authors:	黃建智(Jiann-Jyh Huang);翁豐富(Wong, Fung Fuh)
Contributors:	藥學院藥物化學研究所
Date:	2006-08-23?
Issue Date:	2009-09-07 12:26:19 (UTC+8)
Abstract:	A convenient method for the synthesis 1-substituted imidazoles was developed by the reaction of α-bromoketone with lithium imidazole. The reaction gave the desired products in improved yields without the formation of 1,3-disubstituted imidazolium salts. A mechanistic study on the newly developed nucleophilic substitution was elucidated by use of a strictly geometric 21-bromo-3α-hydroxyl-3β-methoxymethyl-5α-pregnan-20-one. Data from HPLC and proton NMR suggested an epoxide as the intermediate. Lithium imidazole was thus applied for the synthesis of biologically active 3α-hydroxyl-21-(1’-imidazolyl)-3β-methoxymethyl-5α-pregnan-20-one. The key steps were the improvement of stereoselectivity for acetyl isomers in C-17 and the introduction of imidazole into the core structure by use of lithium imidazole. This latter key step provided the desired product in 82% yield without the formation of 1,3-disubstituted imidazolium salt as impurity, which is generally observed in traditional method.
Relation:	2006 藥物化學研討會
Appears in Collections:	[Graduate Institute of Pharmaceutical Chemistry] Proceedings

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