共查询到20条相似文献,搜索用时 11 毫秒
1.
Dr. Yoshinari Sawama Yuko Shishido Takahiro Kawajiri Ryota Goto Dr. Yasunari Monguchi Prof. Dr. Hironao Sajiki 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(2):510-516
Friedel–Crafts benzylations between unactivated arenes and benzyl alcohol derivatives are clean and straightforward processes to construct biologically useful di‐ and tri‐arylmethanes. We have established an efficient iron‐catalyzed Friedel–Crafts benzylation method at room temperature that uses benzyl TMS ethers as substrates, which are poorly reactive under common nucleophilic substitution conditions. The reaction seems to progress through iron‐catalyzed self‐condensation of the benzyl TMS ether to the corresponding dibenzylic ether. The use of excess arene relative to benzyl TMS ether produced mono‐benzylated arene (di‐ and tri‐arylmethane products), whereas the use of excess benzyl TMS ether versus arene provided bis‐benzylated arene (polyarylated products) in high yields and regioselectivities. In previous methods, the latter double Friedel–Crafts benzylations hardly proceed. 相似文献
2.
3.
4.
5.
6.
7.
Dr. Yoshihiro Sohtome Bongki Shin Natsuko Horitsugi Prof. Dr. Keiichi Noguchi Prof. Dr. Kazuo Nagasawa 《化学:亚洲杂志》2011,6(9):2463-2470
Herein, we present details of our conformationally flexible, 1,3‐diamine‐tethered guanidine/bisthiourea organocatalysts for chemo‐, regio‐, and enantioselective 1,4‐type Friedel–Crafts reactions of phenols. These organocatalysts show a unique stereo‐discrimination governed by the differential activation entropy (ΔΔS≠), rather than by the differential activation enthalpy (ΔΔH≠). Extensive kinetic analyses using Eyring plots for a series of guanidine/bisthiourea organocatalysts revealed the key structural motif in the catalysts associated with a large magnitude of differential activation entropy (ΔΔS≠). A plausible guanidine–thiourea cooperative mechanism for the enantioselective Friedel–Crafts reaction is proposed. 相似文献
8.
9.
NIS‐Assisted Aza‐Friedel–Crafts Reaction with α‐Carbamoysulfides as Precursors of N‐Carbamoylimines
下载免费PDF全文
![点击此处可从《Chemistry (Weinheim an der Bergstrasse, Germany)》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Dr. Nicolas George Mathieu Bekkaye Dr. Aurélien Alix Prof. Dr. Jieping Zhu Dr. Géraldine Masson 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(13):3621-3625
A general and practical N‐iodosuccinimide (NIS)‐promoted aza‐Friedel–Crafts reaction of various aromatic nucleophiles with N‐acylimines generated in situ from α‐amidosulfides to give a rapid access to highly functionalized amines is described. The newly developed methodology is very mild, fast, efficient, and complementary. 相似文献
10.
Temperature Dual Enantioselective Control in a Rhodium‐Catalyzed Michael‐Type Friedel–Crafts Reaction: A Mechanistic Explanation
下载免费PDF全文
![点击此处可从《Chemistry (Weinheim an der Bergstrasse, Germany)》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Dr. Isabel Méndez Dr. Ricardo Rodríguez Dr. Víctor Polo Dr. Vincenzo Passarelli Prof. Dr. Fernando J. Lahoz Dr. Pilar García‐Orduña Prof. Dr. Daniel Carmona 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(31):11064-11083
By changing the temperature from 283 to 233 K, the S (99 % ee) or R (96 % ee) enantiomer of the Friedel–Crafts (FC) adduct of the reaction between N‐methyl‐2‐methylindole and trans‐β‐nitrostyrene can be obtained by using (SRh,RC)‐[(η5‐C5Me5)Rh{(R)‐Prophos}(H2O)][SbF6]2 as the catalyst precursor. This catalytic system presents two other uncommon features: 1) The ee changes with reaction time showing trends that depend on the reaction temperature and 2) an increase in the catalyst loading results in a decrease in the ee of the S enantiomer. Detection and characterization of the intermediate metal–nitroalkene and metal–aci‐nitro complexes, the free aci‐nitro compound, and the FC adduct‐complex, together with solution NMR measurements, theoretical calculations, and kinetic studies have allowed us to propose two plausible alternative catalytic cycles. On the basis of these cycles, all the above‐mentioned observations can be rationalized. In particular, the reversibility of one of the cycles together with the kinetic resolution of the intermediate aci‐nitro complexes account for the high ee values achieved in both antipodes. On the other hand, the results of kinetic measurements explain the unusual effect of the increment in catalyst loading. 相似文献
11.
12.
The asymmetric Friedel–Crafts alkylation of electron‐rich N‐containing heterocycles with nitroalkenes under catalysis of diphenylamine‐tethered bis(oxazoline) and bis(thiazoline)‐ZnII complexes was investigated. In the reaction of indole derivatives, the complex of ligand 4 f with trans‐diphenyl substitutions afforded better results than previously published ligand 4 e with cis‐diphenyl substitutions. Excellent yields (up to greater than 99 %) and enantioselectivities (up to 97 %) were achieved in most cases. The complex of ligand 4 d bearing tert‐butyl groups gave the best results in the reactions of pyrrole. Moderate to good yields (up to 91 %) and enantioselectivities (up to 91 %) were achieved in most cases. The origin of the enantioselectivity was attributed to the NH–π interaction between the catalyst and the incoming aromatic system in the transition state. Such an interaction was confirmed through comparison of the enantioselectivity and the absolute configuration of the products in the reactions catalyzed by designed ligands. 相似文献
13.
Feng Zhou Zhong‐Yan Cao Jing Zhang Prof. Dr. Hai‐Bo Yang Prof. Dr. Jian Zhou 《化学:亚洲杂志》2012,7(1):233-241
We report a highly efficient Friedel–Crafts reaction of 3‐alkyl or 3‐aryl 3‐hydroxyoxindoles with a variety of aromatic and heteroaromatic compounds to unsymmetrical 3,3‐diaryloxindoles or 3‐alkyl‐3‐aryloxindoles, which are interesting medicinal targets and useful building blocks for the synthesis of natural products. Hg(ClO4)2 ? 3 H2O was identified as a powerful catalyst for this reaction, and is significantly more efficient than other screened metal perchlorate hydrates and Brønsted acids such as HOTf and HClO4. The high catalytic property of Hg(ClO4)2 ? 3 H2O originates from the unprecedented dual activation effects of aromatic mercuration, which could generate a strong protic acid to facilitate the generation of a carbocation at the C3‐position of oxindoles and simultaneously form the more reactive nucleophilic reaction partner. 相似文献
14.
9‐Membered Carbocycle Formation: Development of Distinct Friedel–Crafts Cyclizations and Application to a Scalable Total Synthesis of (±)‐Caraphenol A
下载免费PDF全文
![点击此处可从《Angewandte Chemie (International ed. in English)》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Nathan E. Wright Prof. Dr. Scott A. Snyder 《Angewandte Chemie (International ed. in English)》2014,53(13):3409-3413
Explorations into a series of different approaches for 9‐membered carbocycle formation have afforded the first reported example of a 9‐exo‐dig ring closure via a AuIII‐promoted reaction between an alkyne and an aryl ring as well as several additional, unique Friedel–Crafts‐type cyclizations. Analyses of the factors leading to the success of these transformations are provided, with the application of one of the developed 9‐membered ring closures affording an efficient and scalable synthesis of the bioactive resveratrol trimer caraphenol A. That synthesis proceeded with an average yield of 89 % per step (7.8 % overall yield) and has provided access to more than 600 mg of the target molecule. 相似文献
15.
16.
17.
An Arylation Strategy to Propargylamines: Catalytic Asymmetric Friedel–Crafts‐type Arylation Reactions of C‐Alkynyl Imines
下载免费PDF全文
![点击此处可从《Angewandte Chemie (International ed. in English)》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Yingcheng Wang Liang Jiang Long Li Jun Dai Dan Xiong Prof. Dr. Zhihui Shao 《Angewandte Chemie (International ed. in English)》2016,55(48):15142-15146
The first arylation strategy for the synthesis of enantioenriched propargylamines is disclosed. This approach, which is complementary to previous alkynylation and alkylation strategies, involves a C(sp2)?C(sp3) bond formation, and is based on the first asymmetric Friedel–Crafts‐type arylation reaction of C‐alkynyl imines. Asymmetric Friedel–Crafts reactions with electron‐deficient phenols, a longstanding unsolved challenge, have thus been realized for the first time, enabled by the combination of our recently introduced C‐alkynyl N‐Boc‐protected N,O‐acetals as electrophiles and chiral phosphoric acids as catalysts. The synthetic utility of the resulting structurally diverse and polyfunctional chiral propargylamines was demonstrated by a series of selective transformations, including controlled reduction of the alkynyl group and iterative cross‐couplings. 相似文献
18.
Ghezalla Tabak Thi-Nhn Pham Guy Levesque Rachid Haraoubia 《Journal of polymer science. Part A, Polymer chemistry》1998,36(1):117-127
Thioamide groups were introduced into polystyrenes by the Friedel–Crafts reaction, with phenyl isothiocyanate in nitromethane solution, in the presence of anhydrous aluminium chloride. Free radical copolymerization of 4-vinyl dithiobenzoate with styrene followed by low-temperature solution condensation reactions, with excess of amines in N,N-dimethylformamide, offered another synthetic route to (co)polymers containing thioamine groups in the side chains without crosslinking. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 117–127, 1998 相似文献
19.
Frontispiece: Entropy‐Driven 1,2‐Type Friedel–Crafts Reaction of Phenols with N‐tert‐Butoxycarbonyl Aldimines
下载免费PDF全文
![点击此处可从《Chemistry (Weinheim an der Bergstrasse, Germany)》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Masaru Kato Shogo Hirao Katsuhiro Nakano Dr. Makoto Sato Prof. Dr. Masahiro Yamanaka Dr. Yoshihiro Sohtome Prof. Dr. Kazuo Nagasawa 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(51)