Ugi/Robinson-Gabriel reactions directed toward the synthesis of 2,4,5-trisubstituted oxazoles

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• 作者：Arthur Y. Shaw^a ; Zhigang Xu^a ; Christopher Hulme^a ; ^b ; ^{hulme@pharmacy.arizona.edu}
• 关键词：Multicomponent reactions ; Ugi reaction ; Robinson&ndash ; Gabriel reaction ; 2 ; 4 ; 5-Trisubstituted oxazoles ; Vilsmeier&ndash ; Haack reaction
• 刊名：Tetrahedron Letters
• 出版年：2012
• 期刊代码：109_00404039
• 类别：ch
• 出版时间：11 April, 2012
• 卷：53
• 期：15
• 页码：1998-2000
• 文件大小：373 K

摘要

This Letter discloses a novel concise synthesis of a series of 2,4,5-trisubstituted oxazoles via a tandem Ugi/Robinson-Gabriel sequence. Herein, 2,4-dimethoxybenzylamine 1 was used as an ammonia equivalent in combination with arylglyoxal 3 and supporting Ugi reagents, an isonitrile and carboxylic acid. As such the product of the acid treated Ugi intermediate is ideally configured to undergo a Robinson-Gabriel cyclodehydration reaction to yield the desired oxazole scaffold 5.