A general method for alkali-metal-promoted reductive difunctionalization of alkenes has been developed by means of reduction-resistant alkoxy-substituted electrophiles. A series of 1,2-diboration and 1,2-dicarbofunctionalization products can be synthesized by employing trimethoxyborane and strained cyclic ethers such as oxirane and oxetane. In addition, unsymmetrical carbo- or thioborations have been
Stereocontrolled Synthesis of Contiguous C(sp<sup>3</sup>)−C(aryl) Bonds by Lanthanide(III)-Catalyzed Domino Aryl-Claisen [3,3]-Sigmatropic Rearrangements
作者:Timothy R. Ramadhar、Jun-ichi Kawakami、Alan J. Lough、Robert A. Batey
DOI:10.1021/ol1018147
日期:2010.10.15
A domino [3,3]-sigmatropic aryl-Claisen rearrangement of cyclic and acyclic bisaryloxy-substituted alkenes can be performed in high yield by using Ln(fod)3 catalysis to obtain bisphenolic products incorporating two contiguous aryl−C(sp3) bonds. Stereospecific rearrangement was observed for cyclic substrates. The precursordiaryl ethers were typically synthesized from the corresponding diols by double
Enantioselective, Stereoconvergent Resolution Copolymerization of Racemic
<i>cis</i>
‐Internal Epoxides and Anhydrides
作者:Guang‐Hui He、Bai‐Hao Ren、Shi‐Yu Chen、Ye Liu、Xiao‐Bing Lu
DOI:10.1002/anie.202011259
日期:2021.3.8
unreacted epoxide at various conversions. Catalytic activity and copolymer enantioselectivity are strongly influenced by the phenolate ortho‐substituents of the ligand set, as well as the axial linker and its chirality. An enantiopure binaphthol‐linked bimetallic AlIII complex allows stereoconvergent access to the stereoregular semi‐crystalline polyesters and a concomitant kinetic resolution of the
外消旋的顺式-内部环氧化物和酸酐的前所未有的对映选择性拆分共聚反应,是由具有多个手性的双核铝配合物介导的,提供了具有两个连续立体中心的旋光聚酯,以及未反应的底物具有良好的对映选择性。在该拆分共聚中观察到了意外的立体收敛,其中共聚物的对映选择性形成的选择性因子大大超过了在各种转化率下基于未反应的环氧化物的动力学拆分系数。催化活性和共聚物的对映选择性受配体组的酚酸酯邻位取代基,轴向连接基及其手性的影响很大。对映纯联萘酚双金属Al III 配合物可以使立体收敛地接触到有规立构的半结晶聚酯,并伴随着环氧底物的动力学拆分。
Synthetic applications of functionalized silyl anions: Aminosilyl anions as hydroxy anion equivalent
作者:Kohei Tamao、Atsushi Kawachi、Yoko Tanaka、Hitoshi Ohtani、Yoshihiko Ito
DOI:10.1016/0040-4020(96)00212-8
日期:1996.4
An (aminosilyl)lithium and the corresponding copper and magnesium reagents serve as a hydroxy anion equivalent through (1) allylic substitution, (2) addition to vinyloxirane, and (3) addition to acetylene, followed by oxidative cleavage of the silicon-carbon bonds. Highly regio- and stereoselective transformations have been achieved in all cases.
Stereoselective preparation of phosphine oxides via a 2,3-sigmatropic shift of allylic diphenylphosphinites
作者:Stéphane Demay、Klaus Harms、Paul Knochel
DOI:10.1016/s0040-4039(99)00952-1
日期:1999.7
The thermic rearrangement of various chiral or racemic allylic diphenylphosphinites to allylic phosphine oxides has been applied for the preparation of several chiral diphosphine oxides of interest for asymmetric catalysis.