Aminocarbenechromium complexes of the general structure (CO)5CrC(R)N-(CH2)nXCH2 (n = 0, X CH2; n = 1, X CH2; n = 1, X CHCH; n = 2, X molecules of alkyne and one molecule of CO, and CN bond cleavage, new polycyclic heterocycles. The reactions of the pyrroline-, the tetrahydropyridine-, the pyrrolidine- and the methylaziridine-substituted complexes are mainly considered, and the results of
Physical Organic Chemistry of Transition Metal Carbene Complexes. 29. Kinetics of Reactions of [Ethoxy(phenyl)carbene]pentacarbonylchromium(0) and [Ethoxy(phenyl)(Cr(CO)<sub>3</sub>)carbene]pentacarbonylchromium(0) with Water, OH<sup>-</sup>, and Amines. Mechanistic Changes Induced by the Cr(CO)<sub>3</sub> Group
作者:Claude F. Bernasconi、Santanu Bhattacharya
DOI:10.1021/om030696f
日期:2004.4.1
minor effect on the electrophilic reactivity of the carbene carbon; that is, the nucleophilic attack by OH- and the amines on 7-Cr and 8-Cr occurs at similar rates. However, the Cr(CO)3 group exerts a strong influence on the mechanisms of both types of reactions, which results in changes of what steps are rate limiting. In the hydrolysis reaction these changes lead to a more complex rate versus pH
(CO)5 Cr C(OEt)C 6 H 5(7-Cr)和(CO)5 Cr C(OEt)C 6 H 5(Cr(CO)3)(8-Cr)氨解的动力学研究报道了由5种伯脂族胺和25-℃下50%MeCN-50%水(v / v)中8-Cr的水解。Cr(CO)3基团的引入对卡宾碳的亲电反应性影响很小。即,由OH的亲核攻击-和胺7 -铬和8的Cr以相似的速率发生。但是,Cr(CO)3组对这两种类型的反应机理都有很大的影响,从而改变了限制速率的步骤。在水解反应中,与先前报道的7-Cr相比,这些变化导致8-Cr的速率与pH曲线更为复杂。在氨解反应中,其作用是改变一般的碱催化机理,从7-Cr反应的限速离去基团离开转变为8-Cr反应的限速质子转移。我们将对这些更改的原因进行详细分析。
Reaction of aminocarbene complexes of chromium with alkynes. 2. Intramolecular insertions leading to polycyclic lactams
作者:Evelyne Chelain、Andree Parlier、Max Audouin、Henri Rudler、Jean Claude Daran、Jacqueline Vaissermann
DOI:10.1021/ja00076a015
日期:1993.11
Thermolysis of chromium-containing carbene complexes of the general structure (CO) 5 Cr=C(NR 2 R 3 )-(CH 2 ) n C=C-R 1 has been examined. When nitrogen is part of a strained cycle (R 2 R 3 =(CH 2 ) m , m=2, 3) or in an allylic position, or if m>4, then the insertions of the triple bond and of CO, followed by a rearrangement to tricyclic lactams, are observed. This was the case for 14 (R 2 R 3 =(CH
已经检查了一般结构 (CO) 5 Cr=C(NR 2 R 3 )-(CH 2 ) n C=CR 1 的含铬卡宾配合物的热解。当氮是应变循环的一部分 (R 2 R 3 =(CH 2 ) m , m=2, 3) 或处于烯丙基位置时,或者如果 m>4,则三键和 CO 的插入,随后通过重排为三环内酰胺,观察到。14 (R 2 R 3 =(CH 2 ) 3 ,n=4,R 1 =Ph),18 (R 2 R 3 =(CH 2 ) 3 ,n=3,R 1 =Ph) 就是这种情况),对于 27 (R 2 R 3 =CH 2 CH=CHCH 2 ,n=4,R 1 =Ph),分别导致 15、19 和 28,其结构可以通过 X 射线确定晶体学
Reaction of aminocarbene complexes of chromium with alkynes 10. From large to small cyclic amines: single versus double alkyne insertions
of comparing the reaction of various aminocarbene complexes of chromium with alkynes and to ascertain several points of the mechanism of their interaction, a series of complexes derived from large cyclic amines, HN(CH2)n (n≥6) and from a small cyclic amine (n=2) was synthesized. In the case of the larger amines, all the complexes examined herein, led to the expected bridgehead lactams 12 as the major
Control over the <i>E</i>/<i>Z</i> Selectivity of the Catalytic Dimerization of Group 6 (Fischer) Metal Carbene Complexes
作者:Gong M. Chu、Israel Fernández、Miguel A. Sierra
DOI:10.1021/jo302130h
日期:2013.2.1
additives in the reaction of self-dimerization of alkoxychromium(0) (Fischer) carbenecomplexes resulted in the selection of Pd(PtBu3)2 to effect this transformation with good to excellent E selectivities and acceptable to excellent chemical yields. This catalyst will allow the control of the geometry in the synthesis of polyconjugated olefins, one emerging application of these catalytic reactions.
对烷氧基铬(0)(Fischer)卡宾配合物自二聚反应中不同催化剂和添加剂的影响进行系统研究后,选择了Pd(P t Bu 3)2来实现具有良好或优异E的转化。选择性和优良的化学收率是可以接受的。该催化剂将允许控制聚共轭烯烃的合成中的几何形状,这些催化反应的一种新兴应用。