共查询到20条相似文献,搜索用时 0 毫秒
1.
2.
An efficient NaBArF4‐catalyzed oxidative cyclization of readily available 1,5‐ and 1,6‐diynes has been developed. Importantly, this transition metal‐free oxidative catalysis proceeds via a presumable Lewis acid‐catalyzed SN2’ pathway, which is distinct from the relevant oxidative rhodium and gold catalysis. This method leads to the facile and practical construction of a diverse range of synthetically useful γ‐ and δ‐lactams in mostly good to excellent yields with broad substrate scope. 相似文献
3.
4.
Palladium‐Catalyzed Enantioselective Reductive Heck Reactions: Convenient Access to 3,3‐Disubstituted 2,3‐Dihydrobenzofuran
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)
Zhan‐Ming Zhang Bing Xu Yanyan Qian Lizuo Wu Yuanqi Wu Lujia Zhou Prof. Dr. Yu Liu Prof. Dr. Junliang Zhang 《Angewandte Chemie (International ed. in English)》2018,57(32):10373-10377
The first example of highly enantioselective intramolecular hydroarylation of allyl aryl ethers was realized by palladium‐catalyzed reductive heck reactions utilizing a new chiral sulfinamide phosphine ligand (N‐Me‐ XuPhos ). N‐Me‐ XuPhos can be easily prepared on gram scale from readily available starting materials in a one‐pot synthesis approach. A series of optically active 2,3‐dihydrobenzofurans bearing a quaternary stereocenter were obtained in good yields and with excellent enantioselectivities. The practicality of this reaction was validated in the straightforward synthesis of CB2 receptor agonists. Moreover, deuterium was efficiently incorporated into the products. 相似文献
5.
6.
Combining Photoredox‐Catalyzed Trifluoromethylation and Oxidation with DMSO: Facile Synthesis of α‐Trifluoromethylated Ketones from Aromatic Alkenes
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)
Ren Tomita Dr. Yusuke Yasu Dr. Takashi Koike Prof. Dr. Munetaka Akita 《Angewandte Chemie (International ed. in English)》2014,53(28):7144-7148
Trifluoromethylated ketones are useful building blocks for organic compounds with a trifluoromethyl group. A new and facile synthesis of ketones with a trifluoromethyl substituent in the α‐position proceeds through a one‐pot photoredox‐catalyzed trifluoromethylation–oxidation sequence of aromatic alkenes. Dimethyl sulfoxide (DMSO) serves as a key and mild oxidant under these photocatalytic conditions. Furthermore, an iridium photocatalyst, fac[Ir(ppy)3] (ppy=2‐phenylpyridine), turned out to be crucial for the present photoredox process. 相似文献
7.
8.
9.
10.
Liliana Boiaryna Dr. Mohamed Kamal El Mkaddem Dr. Catherine Taillier Prof. Vincent Dalla Dr. Mohamed Othman 《Chemistry (Weinheim an der Bergstrasse, Germany)》2012,18(44):14192-14200
Gold catalysts have been applied in cascade‐type reactions for the synthesis of different nitrogen‐based compounds. The reactions likely proceed by a new gold‐catalyzed cascade intermolecular α‐amidoalkylation/intramolecular carbocyclization cascade process by unifying both the σ‐ and π‐Lewis acid properties of the gold salts. In the first part of this report we show that the σ‐Lewis acidity of gold(I) and gold(III) could be exploited to efficiently catalyze the nucleophilic substitution of various alkoxy‐ and acetoxylactams. The reaction was found to be applicable to a wide range of cyclic N‐acyliminium ion precursors and various nucleophiles, including allyltrimethylsilane, silyl enol ethers, arenes, and active methylene derivatives. As a logical progression of this study, a combined hard/soft binary catalytic gold system was then used to implement an unprecedented tandem intermolecular Friedel–Crafts amidoalkylation/intramolecular hydroarylation sequence allowing an expedient access to new, complex, fused polyheterocyclic structures from trivial materials. 相似文献
11.
Hydrogenative Dearomatization of Pyridine and an Asymmetric Aza‐Friedel–Crafts Alkylation Sequence
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)
Shuo‐Guo Wang Prof. Dr. Shu‐Li You 《Angewandte Chemie (International ed. in English)》2014,53(8):2194-2197
Highly efficient synthesis of enantiomerically enriched substituted piperidines has been realized via chiral phosphoric acid catalyzed cascade hydrogenative dearomatization of substituted pyridines and aza‐Friedel‐Crafts reaction in good to excellent yields and enantioselectivity. 相似文献
12.
13.
14.
Zinc‐Catalyzed Alkyne Oxidation/CH Functionalization: Highly Site‐Selective Synthesis of Versatile Isoquinolones and β‐Carbolines
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)
Long Li Bo Zhou Yong‐Heng Wang Chao Shu Yi‐Fei Pan Prof. Dr. Xin Lu Prof. Dr. Long‐Wu Ye 《Angewandte Chemie (International ed. in English)》2015,54(28):8245-8249
An efficient zinc(II)‐catalyzed alkyne oxidation/C? H functionalization sequence was developed, thus leading to highly site‐selective synthesis of a variety of isoquinolones and β‐carbolines. Importantly, in contrast to the well‐established gold‐catalyzed intermolecular alkyne oxidation, over‐oxidation can be completely suppressed in this system and the reaction most likely proceeds by a Friedel–Crafts‐type pathway. Mechanistic studies and theoretical calculations are described. 相似文献
15.
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
16.
17.
Pd‐Catalyzed Carboamination of Alkylidenecyclopropanes: Synthesis of Congested Pyrrolidines and Piperidines
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)
Phillip R. Lazzara Keegan P. Fitzpatrick Dr. Chad C. Eichman 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(47):16779-16782
The synthesis of densely functionalized N‐heterocycles is an ongoing challenge in chemical synthesis. Herein, we report an efficient method for the construction of pyrrolidine and piperidine scaffolds using a palladium‐catalyzed carboamination of alkylidenecyclopropanes. 相似文献
18.
Xin Liu Ze‐Shu Wang Tong‐Yi Zhai Chen Luo Yi‐Ping Zhang Yang‐Bo Chen Chao Deng Rai‐Shung Liu Long‐Wu Ye 《Angewandte Chemie (International ed. in English)》2020,59(41):17984-17990
Here an efficient copper‐catalyzed cascade cyclization of azide‐ynamides via α‐imino copper carbene intermediates is reported, representing the first generation of α‐imino copper carbenes from alkynes. This protocol enables the practical and divergent synthesis of an array of polycyclic N‐heterocycles in generally good to excellent yields with broad substrate scope and excellent diastereoselectivities. Moreover, an asymmetric azide–ynamide cyclization has been achieved with high enantioselectivities (up to 98:2 e.r.) by employing BOX‐Cu complexes as chiral catalysts. Thus, this protocol constitutes the first example of an asymmetric azide–alkyne cyclization. The proposed mechanistic rationale for this cascade cyclization is further supported by theoretical calculations. 相似文献
19.
20.
Rhodium(II)‐Catalyzed Cycloaddition Reactions of Non‐classical 1,5‐Dipoles for the Formation of Eight‐Membered Heterocycles
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)
Dong Jin Lee Donguk Ko Prof. Eun Jeong Yoo 《Angewandte Chemie (International ed. in English)》2015,54(46):13715-13718
A new type of intermolecular rhodium(II)‐catalyzed [5+3] cycloaddition has been developed. This higher‐order cycloaddition between pyridinium zwitterion 1,5‐dipole equivalents and enol diazoacetates enables the formation of eight‐membered heterocyclic skeletons, which are otherwise difficult to construct. The optimized cycloaddition occurs efficiently under mild conditions with a wide range of pyridinium zwitterions and with high functional‐group tolerance. 相似文献