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A Direct, Early Stage Guanidinylation Protocol for the Synthesis of Complex Aminoguanidine-containing Natural Products
Published on: September 9, 2016
In Situ Formed N-Sulfonyl Guanidinium for Efficient Amide Coupling
Yue Zhang1, Hongyun Li1, Weifeng Wang1
1Key Laboratory of Bioorganic Phosphorus Chemistry and Chemical Biology (Ministry of Education), Department of Chemistry, Tsinghua University, Beijing100084, China.
Abstract:
Amides are ubiquitous in the world; therefore, it is highly desired to develop an effective and practical method for the synthesis of amides. In this paper, in situ formed N-sulfonyl guanidinium by inexpensive 2-(tert-butyl)-1,1,3,3-tetramethylguanidine and trifluoromethanesulfonic anhydride was used as the efficient and robust coupling reagent of carboxylic acids and amines. In this protocol, reactions of N-sulfonyl guanidinium with carboxylic acids provided carboxylic acid-sulfonic acid mixed anhydrides, and treatments of the mixed anhydrides with 2-(tert-butyl)-1,1,3,3-tetramethylguanidine afforded N-acyl guanidiniums. Subsequent nucleophilic attacks of amines to highly active mixed anhydrides or N-acyl guanidiniums in the presence of 2-(tert-butyl)-1,1,3,3-tetramethylguanidine at room temperature gave corresponding amides or dipeptides (almost without epimerization) in excellent yields. Therefore, the present method provides a novel and useful strategy for the synthesis of amides and peptides.
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