Iridium-Catalyzed Kinetic Asymmetric Transformations of Racemic Allylic Benzoates
摘要:
Versatile methods for iridium-catalyzed, kinetic asymmetric substitution of racemic, branched allylic esters are reported. These reactions occur with a variety of aliphatic, aryl, and heteroaryl allylic benzoates to form the corresponding allylic substitution products in high yields (74-96%) with good to excellent enantioselectivity (84-98% ee) with a scope that encompasses a range of anionic carbon and heteroatom nucleophiles. These kinetic asymmetric processes occur with distinct stereochemical courses for racemic aliphatic and aromatic allylic benzoates, and the high reactivity of branched allylic benzoates enables enantioselective allylic substitutions that are slow or poorly selective with linear allylic electrophiles.
Nucleophilic Reactivities of Imide and Amide Anions
作者:Martin Breugst、Takahiro Tokuyasu、Herbert Mayr
DOI:10.1021/jo1009883
日期:2010.8.6
1994, 33, 938−957), allowing us to determine the nucleophilicity parameters N and the nucleophile-specific parameters s for these nucleophiles. The reactivities of all sulfonamide and diacylimide anions are found in a relatively small range (15 < N < 22). Comparison with structurally related carbanions revealed that amide and imide anions are less reactive than carbanions of the same pKaH. These effects
在DMSO和乙腈溶液中,通过紫外可见光谱研究了酰胺和酰亚胺阴离子2a - o与二苯甲基铵离子1a - i和与结构相关的醌甲基化物1j - q的反应动力学。二阶速率常数(日志ķ 2)与亲电性参数线性相关ë的1A - q根据相关日志ķ 2 =小号(Ñ + ë)(Angew化学,诠释埃德英格兰。。。1994年,33(938-957),这使我们能够确定这些亲核试剂的亲核参数N和亲核试剂特异性参数s。发现所有磺酰胺和二酰基酰亚胺阴离子的反应性都在相对较小的范围内(15 < N <22)。与结构相关的碳负离子的比较显示,酰胺和酰亚胺阴离子的反应性低于相同p K aH的碳负离子。这些作用可以归因于酰胺或酰亚胺阴离子中孤对之一的不存在共振稳定作用。由于酰胺和酰亚胺阴离子仅在氮原子上受到苄鎓离子的攻击,因此必须修改科恩布鲁姆对酰胺阴离子的环境反应性的解释。
Enantioselective Iridium-Catalyzed Allylic Amination of Ammonia and Convenient Ammonia Surrogates
作者:Mark J. Pouy、Andreas Leitner、Daniel J. Weix、Satoshi Ueno、John F. Hartwig
DOI:10.1021/ol701562p
日期:2007.9.1
Iridium-catalyzed, asymmetric allylation of ammonia as a nucleophile occurs with stereoselectivity to form a symmetric diallylamine, and related allylation of the inexpensive ammoniaequivalent potassium trifluoroacetamide or the highly reactive ammoniaequivalent lithium di-tert-butyliminodicarboxylate forms a range of conveniently protected, primary, alpha-branched allylicamines in high yields,
Iridium-Catalyzed Kinetic Asymmetric Transformations of Racemic Allylic Benzoates
作者:Levi M. Stanley、Chen Bai、Mitsuhiro Ueda、John F. Hartwig
DOI:10.1021/ja103779e
日期:2010.7.7
Versatile methods for iridium-catalyzed, kinetic asymmetric substitution of racemic, branched allylic esters are reported. These reactions occur with a variety of aliphatic, aryl, and heteroaryl allylic benzoates to form the corresponding allylic substitution products in high yields (74-96%) with good to excellent enantioselectivity (84-98% ee) with a scope that encompasses a range of anionic carbon and heteroatom nucleophiles. These kinetic asymmetric processes occur with distinct stereochemical courses for racemic aliphatic and aromatic allylic benzoates, and the high reactivity of branched allylic benzoates enables enantioselective allylic substitutions that are slow or poorly selective with linear allylic electrophiles.