Examination of Homo-[3 + 2]-Dipolar Cycloaddition: Mechanistic Insight into Regio- and Diastereoselectivity
作者:Avedis Karadeolian、Michael A. Kerr
DOI:10.1021/jo702073w
日期:2007.12.1
The reaction of 2,3-disubstituted-1,1-cyclopropanediesters with nitrones under Lewis acid conditions produces tetrahydro-1,2-oxazines in which the cis/trans relationship of the cyclopropanes is not conserved. Reacting nitrones with 2,3-cis-disubstituted cyclopropanes lead to 5,6-trans-oxazines, and 2,3-trans-disubstituted cyclopropanes lead to 5,6-cis-oxazines. This observed stereochemical inversion
在路易斯酸条件下,2,3-二取代的1,1-环丙烷二酯与硝基反应生成四氢-1,2-恶嗪,其中环丙烷的顺式/反式关系不守恒。硝酮与2,3-顺式二取代的环丙烷反应生成5,6-反式恶嗪,而2,3-反式二取代的环丙烷则生成5,6-顺式恶嗪。这种观察到的立体化学转化为制备四氢-1,2-恶嗪的逐步环化机理提供了证据。