Anionic cyclizations of alpha-aminoorganolithiums. Determination of the stereoselectivity at the carbanion center and the synthesis of (+)-pseudoheliotridane
Anionic cyclizations of alpha-aminoorganolithiums. Determination of the stereoselectivity at the carbanion center and the synthesis of (+)-pseudoheliotridane
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DOI：
10.1021/ja9607906
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发表时间：
1996-06-05
影响因子：
15
通讯作者：
Snowden, DJ
中科院分区：
文献类型：
--
作者：
Coldham, I;Hufton, R;Snowden, DJ
最近许多研究小组对R-氨基有机锂的构型稳定性感兴趣，发现在低温下，锡-锂交换和外部亲电试剂的淬灭都可以在负碳离子中心进行完全的构型稳定性。已知发生构型保留、反转和外消旋的反应。[1]最近Gawley 2报道了在[2，3]-σ迁移重排过程中，在R-氨基碳负离子中心发生构型反转。本文报道了在阴离子环化反应中碳负离子中心的立体选择性的第一个例子。此外，我们报告的第一个显着的例子的R-氨基有机锂，这是在室温下构型稳定。
The recent interest in the configurational stability of R-aminoorganolithiums by a number of research groups1 has led to the discovery that at low temperatures both a tin-lithium exchange and quench by an external electrophile can proceed with complete configurational stability at the carbanion center. Reactions occurring with retention, inversion, and racemization of configuration are known. 1 Recently, Gawley2 has reported that inversion of configuration occurs at the R-aminocarbanion center during a [2, 3]-sigmatropic rearrangement. In this communication we report the first example of the stereoselectivity at the carbanion center during an anionic cyclization. In addition, we report the first remarkable example of an R-aminoorganolithium which is configurationally stable at room temperature.