Transition-Metal Aqua Complexes of 4,6-Dibenzofurandiyl-2,2‘-bis(4-phenyloxazoline). Effective Catalysis in Diels−Alder Reactions Showing Excellent Enantioselectivity, Extreme Chiral Amplification, and High Tolerance to Water, Alcohols, Amines, and Acids
作者:Shuji Kanemasa、Yoji Oderaotoshi、Shin-ichi Sakaguchi、Hidetoshi Yamamoto、Junji Tanaka、Eiji Wada、Dennis P. Curran
DOI:10.1021/ja973519c
日期:1998.4.1
from nickel(II) perchlorate hexahydrate has an octahedral structure with three aqua ligands, and it can be isolated and stored for months without loss of catalytic activity. Iron(II), cobalt(II), copper(II), and zinc(II) complexes are similarly active. The absoluteconfiguration induced in the reaction can be readily predicted on the basis of the C2-symmetric structure of the complexes as well as the
阳离子水配合物由反式螯合三齿配体 (R,R)-4,6-二苯并呋喃二基-2,2'-双(4-苯基恶唑啉) (DBFOX/Ph) 和各种过渡金属 (II) 制备高氯酸盐。这些配合物是环戊二烯与 3-烯酰基-2-恶唑烷酮亲二烯体的 Diels-Alder 反应的有效催化剂,并显示出优异的对映选择性。由六水合高氯酸镍 (II) 制备的活性催化剂配合物具有八面体结构和三个水配体,可以分离和储存数月而不会损失催化活性。铁 (II)、钴 (II)、铜 (II) 和锌 (II) 配合物具有类似的活性。根据配合物的 C2 对称结构以及底物配合物的简单结构,可以很容易地预测反应中诱导的绝对构型。由 Ni(II) 或 Zn(II) 高氯酸盐制备的水络合物在 Diels-Alder 反应中产生高效的手性放大。使用 DBFOX/Ph 配体...
Site-specific introduction of gold-carbenoids by intermolecular oxidation of ynamides or ynol ethers
作者:Paul W. Davies、Alex Cremonesi、Nicolas Martin
DOI:10.1039/c0cc02736g
日期:——
Ynamides and ynol ethers undergo intermolecular gold-catalysed reaction with a nucleophilic oxidant to access metal-carbenoid reactivity patterns. A site-specific oxidation/1,2-insertion cascade is used for a general access to functionalised α,β-unsaturated carboxylic acid derivatives and vinylogous carbimates.
electron-deficient olefins gave substituted hydrocarbazoles in up to 99% yield and 94% ee. This reaction was catalyzed by a novel chiral holmium(III) complex. Alkylation of the cycloadduct gave a tricyclic compound with four continuous chiral centers, one of which was a quaternarycarbon.
Regioselective functionalisation of dibenzothiophenes through gold-catalysed intermolecular alkyne oxyarylation
作者:Matthew J. Barrett、Paul W. Davies、Richard S. Grainger
DOI:10.1039/c5ob01241d
日期:——
Site-selective and direct C–H functionalisation of dibenzothiophenes is achieved using a gold-catalysed oxyarylation approach.
通过金催化的氧化芳基化方法实现了对二苯并噻吩的位选择性和直接C-H官能化。
Lanthanide triflate-catalyzed 1,3-dipolar cycloaddition reactions of polymer-supported nitrones with alkenes for the preparation of diverse 2-isoxazoline derivatives
作者:Shū Kobayashi、Ryo Akiyama
DOI:10.1016/s0040-4039(98)02100-5
日期:1998.12
1,3-Dipolar cycloadditionreactions of polymer-supported nitrones with alkenes proceeded smoothly in the presence of a catalytic amount of a lanthanide triflate to afford the corresponding 2-isoxazolines in high yields. Diverse 2-isoxazoline derivatives were prepared based on these solid-phase reactions.