Rotational isomers of N-methyl-N-arylacetamides and their derived enolates: implications for asymmetric Hartwig oxindole cyclizations.
Rotational isomers of N-methyl-N-arylacetamides and their derived enolates: implications for asymmetric Hartwig oxindole cyclizations.
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DOI：
10.1021/jo400385t
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发表时间：
2013-04-19
期刊：
影响因子：
--
通讯作者：
Curran DP
中科院分区：
文献类型：
--
作者：
Mandel J;Pan X;Hay EB;Geib SJ;Wilcox CS;Curran DP
研究了N-（2-溴-4，6-二甲基苯基）-N-甲基-2-苯基丙酰胺作为Hartwig不对称羟吲哚环化反应前体模型的旋转选择性.用快速色谱法分离了该化合物的阻转异构体，然后对对映体进行了拆分，并研究了立体中心和N-Ar轴的相互转化。在热条件下，轴非常稳定。在Hartwig环化的基本条件下，立构中心和手性轴通过烯醇化物的形成而平衡。2-苯基乙酰胺类似物的N-Ar旋转势垒从前体的31 kcal mol−1降低到烯醇化物的17 kcal mol−1。这种戏剧性的障碍减少的原因和影响的N-Ar和酰胺C-N旋转Hartwig环化进行了讨论。
The rotational preferences of N-(2-bromo-4,6-dimethylphenyl)-N-methyl 2-phenyl-propanamide were studied as a model of precursors for Hartwig asymmetric oxindole cyclizations. The atropisomers of this compound were separated by flash chromatography, then the enantiomers were resolved and the interconversions of the stereocenter and the N–Ar axis were studied. Under thermal conditions, the axis is very stable. Under the basic conditions of the Hartwig cyclization, both the stere-ocenter and the chiral axis equilibrate via enolate formation. The N–Ar rotation barrier of a 2-phenylacetamide analog was reduced from 31 kcal mol−1 in the precursor to 17 kcal mol−1 in the enolate. Reasons for this dramatic barrier reduction and implications of both N–Ar and amide C–N rotations for Hartwig cyclizations are discussed.
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影响因子：
15
作者：
Guthrie, David B.;Geib, Steven J.;Curran, Dennis P.
通讯作者：
Curran, Dennis P.
影响因子：
3.2
作者：
Cozzi, F;Siegel, JS
通讯作者：
Siegel, JS
影响因子：
1.8
作者：
Arao, T;Kondo, K;Aoyama, T
通讯作者：
Aoyama, T
影响因子：
2.1
作者：
Curran, DP;Chen, CHT;Lapierre, AJB
通讯作者：
Lapierre, AJB
影响因子：
5.2
作者：
Guthrie, David B.;Curran, Dennis P.
通讯作者：
Curran, Dennis P.