Intramolecular Cycloaddition of O-tert-Butyldimethylsilyloximes in the Presence of BF3×OEt2.
Intramolecular Cycloaddition of O-tert-Butyldimethylsilyloximes in the Presence of BF3×OEt2.
复制标题
BF3×OEt2 存在下 O-叔丁基二甲基甲硅烷基肟的分子内环加成。
DOI：
10.1002/chin.200618117
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发表时间：
2006
期刊：
影响因子：
--
通讯作者：
H. Ishibashi*
中科院分区：
文献类型：
--
作者：
O. Tamura;Takahiro Mitsuya;Xin Huang;Yoshiyuki Tsutsumi;Sanae Hattori;H. Ishibashi*
研究了新型1，3-偶极分子N-硼硝酮的分子内环加成反应。用2当量的BF 3·OEt 2处理具有烯烃部分的O-叔丁基二甲基甲硅烷基肟9 − 12生成N-硼烷硝酮，其在萃取后处理后进行分子内环加成得到N-未取代的环加合物16（和/或18）。尽管路易斯酸性条件下，在本环加成反应中，底物的烯烃几何结构保留在环加合物中。N-硼烷硝酮的电子性质似乎是亲电的。在底物11 c的情况下，在烯烃部分的内部位置具有供电子甲基，环加成得到桥联环加合物18 b。环加成反应在较低的温度下进行，非对映选择性高。
Intramolecular cycloaddition of novel 1,3-dipoles,N-boranonitrones, was examined. Treatment ofO-tert-butyldimethylsilyloximes9−12having olefin moieties with 2 equiv of BF3·OEt2generatedN-boranonitrones, which underwent intramolecular cycloaddition to affordN-nonsubstituted cycloadducts16(and/or18) after extractive workup. Despite the Lewis-acidic conditions, the olefin geometry of the substrates was retained in the cycloadducts in the present cycloaddition. The electronic nature of theN-boranonitrones appeared to be electrophilic. In the case of substrate11c, having an electron-donating methyl group at an internal position of the olefin moiety, the cycloaddition gave the bridged cycloadduct18b. The cycloaddition proceeded at relatively low temperature, and the diastereoselectivity was high.