Stereoselective synthesis of 1,2,3-triazolyl-functionalized isoxazolidines, via two consecutive 1,3-dipolar cycloadditions, as precursors of unnatural amino acids
作者:Kaïss Aouadi、Sébastien Vidal、Moncef Msaddek、Jean-Pierre Praly
DOI:10.1016/j.tetlet.2013.01.125
日期:2013.4
isoxazolidines, which were isolated in modest yields. For a general and reliable access to 5-(triazolyl)methyl-substituted isoxazolidines, which are new compounds and valuable precursors of unnatural amino acids, performing the CuAAC cycloaddition as the final step is recommended.
在微波辐射下,将(-)-薄荷酮衍生的硝酮与烯丙基溴进行1,3-偶极环加成,立体选择性地得到相应的手性异恶唑烷,收率为98%。用叠氮化物基团取代溴原子后(收率98%),另一种由各种炔烃进行的1,3-环加成反应生成了一系列1,2,3-三唑基官能化的异恶唑烷(收率约85%)。在酸催化下除去手性助剂似乎是迈向5取代的异恶唑烷的限制步骤,后者以适度的收率分离。为了普遍可靠地获得5-(三唑基)甲基取代的异恶唑烷,它们是新化合物和非天然氨基酸的宝贵前体,建议将CuAAC环加成作为最后一步。