双环[2,2,1]庚-2,5-二烯和环辛-1,5-二烯(联膦)铑四氟硼酸酯在1个大气压下在甲醇或其他极性溶剂中与氢反应。初始产物可以是溶剂化的二氢化物或溶剂化物。根据磷化氢的结构,这两种物质之间的平衡差异很大。当配体为单膦时,二酐通常是稳定的产物,尽管(邻-甲氧基苯基)甲基苯基膦是一个例外。顺式螯合双膦通常形成对氢没有亲和力的溶剂合物。R-苯基双-二苯基膦基乙烷属于此类,但31其配合物的1 H NMR光谱表明单体和二聚体之间达到平衡,三乙胺的添加产生三聚体。反式螯合双膦具有更多的可变性,并且在双1,5-二苯基膦基戊烷的情况下,观察到许多复合物,包括需要CHH活化的复合物。
Stereospecific Copper(II)-Catalyzed Tandem Ring Opening/Oxidative Alkylation of Donor–Acceptor Cyclopropanes with Hydrazones: Synthesis of Tetrahydropyridazines
Aerobic copper(II)-catalyzed tandem ringopening and oxidative C–H alkylation of donor–acceptorcyclopropanes with bisaryl hydrazones is accomplished to produce tetrahydropyridazines, in which copper(II) plays dual role as a Lewis acid as well as redox catalyst. The reaction is stereospecific, and optically active cyclopropanes can be reacted with high optical purities (89–98% enantiomeric excess)
We herein report a transition-metal-free cross-coupling between secondaryalkylhalides/mesylates and aryl/alkenylboronic acid, providing expedited access to a series of nonchiral/chiral coupling products in moderate to good yields. Stereospecific SN2-type coupling is developed for the first time with alkenylboronic acids as pure nucleophiles, offering an attractive alternative to the stereospecific
A new approach to cycloocta[b]indolethroughformal [5+3] cycloaddition was developed. This methodology was realized by using an indolederivative as a C5 unit and a cyclopropane derivative as a C3 unit. Two carbon–carbon bonds were formed stepwise by the addition of a Lewis acidic catalyst and a Brønsted base. The reaction could be performed as a one‐pot process.
通过正式的[5 + 3]环加成反应,开发了一种新的方法来制备环辛八烯[ b ]吲哚。通过使用吲哚衍生物作为C5单元和环丙烷衍生物作为C3单元来实现该方法。通过添加路易斯酸性催化剂和布朗斯台德碱逐步形成两个碳-碳键。该反应可以作为一锅法进行。
(3+3)‐Annulation of Carbonyl Ylides with Donor–Acceptor Cyclopropanes: Synergistic Dirhodium(II) and Lewis Acid Catalysis
作者:Martin Petzold、Peter G. Jones、Daniel B. Werz
DOI:10.1002/anie.201814409
日期:2019.5.6
The first (3+3)‐annulation process of donor–acceptorcyclopropanes using synergistic catalysis is reported. The Rh2(OAc)4‐catalyzed decomposition of diazo carbonyl compounds generated carbonyl ylides in situ. These 1,3‐dipoles were converted with donor–acceptorcyclopropanes, activated by Lewisacid catalysis, to afford multiply substituted pyran scaffolds in high yield and diastereoselectivity. Extensive
Accessing substituted pyrrolidines via formal [3+2] cycloaddition of 1,3,5-triazinanes and donor-acceptor cyclopropanes
作者:Zhi-Yao Chu、Na Li、Dan Liang、Zheng-Hui Li、Yong-Sheng Zheng、Ji-Kai Liu
DOI:10.1016/j.tetlet.2018.01.016
日期:2018.2
The formal [3+2] cycloaddition of 1,3,5-triaryl-1,3,5-triazinanes with donor-acceptor cyclopropanes has been found to provide pyrrolidines in good to excellent yields under mild reaction conditions. Preliminary mechanistic investigation indicates that this formal [3+2] cycloaddition reaction proceeds through competing SN1 and SN2 pathways.
已经发现,在温和的反应条件下,将1,3,5-三芳基-1,3,5-三嗪酮与供体-受体环丙烷进行正式的[3 + 2]环加成反应可提供吡咯烷类化合物。初步的机理研究表明,这种正式的[3 + 2]环加成反应是通过竞争性的S N 1和S N 2途径进行的。