XY–ZH systems as potential 1,3-dipoles. Part 1. Background and scope
作者:Ronald Grigg、H. Q. Nimal Gunaratne、James Kemp
DOI:10.1039/p19840000041
日期:——
XY–ZH Systems are considered in general terms and divided into four classes according to the number of constituent atoms that possess lone-pair electrons. Those systems in which the central Y atom possesses a lone pair are shown to be capable of participating in formal 1,2-H shifts generating 1,3-dipolar species. The scope of the reaction, including its possible relevance to the biochemistry of pyridoxal
X Y–ZH系统被视为通用术语,根据拥有孤对电子的组成原子的数量分为四类。中心Y原子具有孤对的那些系统显示出能够参与形成1,2-H移位的正式1,2-H移位,从而产生1,3-偶极物种。讨论了反应的范围,包括其可能与吡ido醛酶生物化学的相关性,并通过速率数据证明了一系列苯基甘氨酸和丙氨酸甲酯的芳基亚胺环加成N-苯基马来酰亚胺的速率对结构的影响。
Cycloadditions of arylidene imines of α-aminoacidesters to a range of dipolarophiles show substantial rate enhancements in the presence of Bronsted and Lewis acids. For Bronsted acids the rate is related to the pKa of the acid and cycloadditions to reactive dipolarophiles occur at room temperature. For the Lewis acids studied the rate acceleration decreases in the order Zn(OAc)2 > AgOAc > LiOAc >
Highly Enantioselective Copper(I)−Fesulphos-Catalyzed 1,3-Dipolar Cycloaddition of Azomethine Ylides
作者:Silvia Cabrera、Ramón Gómez Arrayás、Juan C. Carretero
DOI:10.1021/ja0552186
日期:2005.11.30
The catalyst system formed by Cu(CH3CN)4ClO4 and the planar chiral P,S-ligand Fesulphos behaves as a very efficient chiral Lewis acid in the catalytic asymmetric 1,3-dipolarcycloaddition of azomethine ylides. This catalyst shows a remarkable reactivity at low catalyst loading (0.5-3 mol %), affording in good yields the endo adducts with exceptional levels of enantioselectivity (up to >99% ee). This
CuI–Fesulphos complexes: efficient chiral catalysts for asymmetric 1,3-dipolar cycloaddition of azomethine ylides
作者:Silvia Cabrera、Ramón Gómez Arrayás、Belén Martín-Matute、Fernando P. Cossío、Juan C. Carretero
DOI:10.1016/j.tet.2007.03.130
日期:2007.7
The Cu-I-Fesulphos catalyst system (<= 3 mol %) shows an excellent performance in the asymmetric 1,3-dipolar cycloaddition of azomethine ylides. High to very high levels of reactivity, endo/exo selectivity, and enantioselectivity ( 69->99% ee) are generally achieved with a very wide range of azomethine ylides and dipolarophiles. Based on experimental and computational studies data, a model that accounts for this high enantiocontrol is proposed. (c) 2007 Elsevier Ltd. All rights reserved.