共查询到20条相似文献,搜索用时 12 毫秒
1.
Rhodium‐Catalyzed Sequential Allylic Amination and Olefin Hydroacylation Reactions: Enantioselective Synthesis of Seven‐Membered Nitrogen 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)
Jeffrey S. Arnold Edward T. Mwenda Prof. Dr. Hien M. Nguyen 《Angewandte Chemie (International ed. in English)》2014,53(14):3688-3692
Dynamic kinetic asymmetric amination of branched allylic acetimidates has been applied to the synthesis of 2‐alkyl‐dihydrobenzoazepin‐5‐ones. These seven‐membered‐ring aza ketones are prepared in good yield with high enantiomeric excess by rhodium‐catalyzed allylic substitution with 2‐amino aryl aldehydes followed by intramolecular olefin hydroacylation of the resulting alkenals. This two‐step procedure is amenable to varied functionality and proves useful for the enantioselective preparation of these ring systems. 相似文献
2.
3.
Dr. Thomas Varlet Damien Bouchet Elsa Van Elslande Dr. Géraldine Masson 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(56):e202201707
We report herein a convenient and scalable dearomative hydroacylation reaction of indoles. Employing readily available aldehydes as the acyl source and TBADT as an inexpensive direct HAT photocatalyst, a variety of indoles derivatives were converted into synthetically interesting 2-acylindolines in good to excellent yields as well as great diastereoselectivity under mild conditions. An asymmetric version of the reaction was successfully developed and an experimental mechanistic investigation was carried out in order to gain further insights on the assumed reaction pathway. 相似文献
4.
Well‐Defined and Robust Rhodium Catalysts for the Hydroacylation of Terminal and Internal 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)
Dr. Amparo Prades Dr. Maitane Fernández Dr. Sebastian D. Pike Prof. Michael C. Willis Prof. Andrew S. Weller 《Angewandte Chemie (International ed. in English)》2015,54(29):8520-8524
A Rh‐catalyst system based on the asymmetric ligand tBu2PCH2P(o‐C6H4OMe)2 is reported that allows for the hydroacylation of challenging internal alkenes with β‐substituted aldehydes. Mechanistic studies point to the stabilizing role of both excess alkene and the OMe‐group. 相似文献
5.
6.
RhIII‐Catalyzed Hydroacylation Reactions between N‐Sulfonyl 2‐Aminobenzaldehydes and Olefins
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)
Tao Zhang Zisong Qi Xueyun Zhang Prof. Lamei Wu Prof. Dr. Xingwei Li 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(12):3283-3287
Metal‐catalyzed hydroacylation of olefins represents an important atom‐economic synthetic process in C?H activation. For the first time highly efficient RhIIICp*‐catalyzed hydroacylation was realized in the coupling of N‐sulfonyl 2‐aminobenzaldehydes with both conjugated and aliphatic olefins, leading to the synthesis of various aryl ketones. Occasionally, oxidative coupling occurred when a silver(I) oxidant was used. 相似文献
7.
Javad Azizian Javad Hosseini Mohammadkazem Mohammadi Fatemeh Sheikholeslami 《合成通讯》2013,43(23):3472-3479
A mild and efficient synthesis of highly substituted pyrroles using the reaction of triphenylphosphine, α-diketone, ammonium acetate, and dialkyl acetylenedicarboxylates is described. 相似文献
8.
In an investigation into the chemical reactions of N‐propargyl pyrroles 1 a – c , containing aldehyde, keto, and ester groups on the pyrrole ring, with [Ru]?Cl ([Ru]=Cp(PPh3)2Ru; Cp=C5H5), an aldehyde group in the pyrrole ring is found to play a crucial role in stimulating the cyclization reaction. The reaction of 1 a , containing an aldehyde group, with [Ru]?Cl in the presence of NH4PF6 yields the vinylidene complex 2 a , which further reacts with allyl amine to give the carbene complex 6 a with a pyrrolizine group. However, if 1 a is first reacted with allyl amine to yield the iminenyne 8 a , then the reaction of 8 a with [Ru]?Cl in the presence of NH4PF6 yields the ruthenium complex 9 a , containing a cationic pyrrolopyrazinium group, which has been fully characterized by XRD analysis. These results can be adequately explained by coordination of the triple bond of the propargyl group to the ruthenium metal center first, followed by two processes, that is, formation of a vinylidene intermediate or direct nucleophilic attack. Additionally, the deprotonation of 2 a by R4NOH yields the neutral acetylide complex 3 a . In the presence of NH4PF6, the attempted alkylation of 3 a resulted in the formation the Fischer‐type amino–carbene complex 5 a as a result of the presence of NH3, which served as a nucleophile. With KPF6, the alkylation of 3 a with ethyl and benzyl bromoacetates afforded the disubstituted vinylidene complexes 10 a and 11 a , containing ester groups, which underwent deprotonation reactions to give the furyl complexes 12 a and 13 a , respectively. For 13 a , containing an O‐benzyl group, subsequent 1,3‐migration of the benzyl group was observed to yield product 14 a with a lactone unit. Similar reactivity was not observed for the corresponding N‐propargyl pyrroles 1 b and 1 c , which contained keto and ester groups, respectively, on the pyrrole ring. 相似文献
9.
Rhodium Enalcarbenoids: Direct Synthesis of Indoles by Rhodium(II)‐Catalyzed [4+2] Benzannulation of Pyrroles
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)
Sudam Ganpat Dawande Vinaykumar Kanchupalli Jagadeesh Kalepu Haribabu Chennamsetti Bapurao Sudam Lad Dr. Sreenivas Katukojvala 《Angewandte Chemie (International ed. in English)》2014,53(16):4076-4080
Disclosed herein is the design of an unprecedented electrophilic rhodium enalcarbenoid which results from rhodium(II)‐catalyzed decomposition of a new class of enaldiazo compounds. The synthetic utility of these enalcarbenoids has been successfully demonstrated in the first transition‐metal‐catalyzed [4+2] benzannulation of pyrroles, thus leading to substituted indoles. The new benzannulation has been applied to the efficient synthesis of the natural product leiocarpone as well as a potent adipocyte fatty‐acid binding protein inhibitor. 相似文献
10.
Efficient Synthesis of Eight‐Membered Nitrogen Heterocycles from O‐Propargylic Oximes by Rhodium‐Catalyzed Cascade Reactions
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)
Prof. Dr. Itaru Nakamura Yoshinori Sato Keisuke Takeda Prof. Dr. Masahiro Terada 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(33):10214-10219
Azocine derivatives were successfully synthesized from O‐propargylic oximes by means of a Rh‐catalyzed 2,3‐rearrangement/heterocyclization cascade reaction. Moreover, the chirality of the substrate was maintained throughout the cascade process to afford the corresponding optically active azocines. 相似文献
11.
Wentao Liu Wenfang Qin Xiaobei Wang Dr. Fei Xue Prof. Xiao‐Yu Liu Prof. Yong Qin 《Angewandte Chemie (International ed. in English)》2018,57(38):12299-12302
The development of efficient syntheses of complex natural products has long been a major challenge in synthetic chemistry. Designing cascade reactions and employing bioinspired transformations are an important and reliable means of achieving this goal. Presented here is a combination of these two strategies, which allow efficient asymmetric synthesis of the cinchona alkaloid (+)‐cinchonidine. The key steps of this synthesis are a controllable, visible‐light‐induced photoredox radical cascade reaction to efficiently access the tetracyclic monoterpenoid indole alkaloid core, as well as a practical biomimetic cascade rearrangement for the indole to quinoline transformation. The use of stereoselective chemical transformations in this work makes it an efficient synthesis of (+)‐cinchonidine. 相似文献
12.
QQ Yang C Xiao LQ Lu J An F Tan BJ Li WJ Xiao 《Angewandte Chemie (International ed. in English)》2012,51(36):9137-9140
Batting the ylides: A simple procedure carried out under mild conditions allows the direct and efficient synthesis of structurally diverse indoles. This approach involves a cascade reaction of sulfur ylides and N-(ortho-chloromethyl)aryl amides. 相似文献
13.
《化学:亚洲杂志》2017,12(18):2383-2387
Efficient [Cu(NHC)]‐catalyzed syntheses of pyrroles via two and three‐component coupling methods are described. Various 1,2‐, 1,2,3‐, 1,2,3,5‐ and fully substituted pyrroles were readily accessible through a suitable choice of ketone, primary amine and diol in a three‐component reaction. The N‐unsubstituted pyrrole formation is also feasible through a two‐component reaction involving a β‐amino alcohol and a ketone. 相似文献
14.
An efficient and operationally simple three-component coupling synthesis of varieties of N-aryl substituted pyrroles is described in the presence of sustainable and environmentally benign metal catalyst, FeCl3. This method provides a straightforward approach for the synthesis of N-aryl substituted pyrroles in good yields from easily accessible starting materials such as nitroalkenes, 1,3-dicarbonyl compounds, and primary aromatic amines. The reaction proceeds through a catalytic sequence of Fe(III)-catalyzed amination/Michael/cycloisomerization reactions. Supplemental materials are available for this article. Go to the publisher's online edition of Synthetic Communications® to view the free supplemental file. 相似文献
15.
Synthesis of Substituted Pyrroles via Copper‐Catalyzed Cyclization of Ethyl Allenoates with Activated Isocyanides
下载免费PDF全文
![点击此处可从《化学:亚洲杂志》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Prof. Kui Lu Fang Ding Long Qin Xiaoliang Jia Chuanming Xu Prof. Xia Zhao Dr. Qingwei Yao Prof. Peng Yu 《化学:亚洲杂志》2016,11(15):2121-2125
A new method for the synthesis of di‐ and trisubstituted pyrroles via copper‐catalyzed cyclization of ethyl allenoates with activated isocyanides has been developed. In contrast to related annulation reactions previously reported, this new process features a skeletal rearrangement in which the aryl sulfonyl moiety, which functions as the electron‐withdrawing group in the α‐carbon of the isocyanide, was found to migrate to the γ‐carbon of the starting allenoate in the final product for the first time. 相似文献
16.
17.
18.
Substrate‐Directed Hydroacylation: Rhodium‐Catalyzed Coupling of Vinylphenols and Nonchelating Aldehydes
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)
Stephen K. Murphy Dr. Achim Bruch Dr. Vy M. Dong 《Angewandte Chemie (International ed. in English)》2014,53(9):2455-2459
We report a protocol for the hydroacylation of vinylphenols with aryl, alkenyl, and alkyl aldehydes to form branched products with high selectivity. This cross‐coupling yields α‐aryl ketones that can be cyclized to benzofurans, and it enables access to eupomatenoid natural products in four steps or less from eugenol. Excellent reactivity and high levels of regioselectivity for the formation of the branched products were observed. We propose that aldehyde decarbonylation is avoided by the use of an anionic directing group on the alkene and a diphosphine ligand with a small bite angle. 相似文献
19.
Gold‐Catalyzed Oxa‐Povarov Reactions for the Synthesis of Highly Substituted Dihydrobenzopyrans from Diaryloxymethylarenes and Olefins
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)
Vinayak Vishnu Pagar Chang‐Chin Tseng Prof. Dr. Rai‐Shung Liu 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(33):10519-10526
Oxa‐Povarov reactions involving readily available diaryloxymethylarenes and aryl‐substituted alkenes are reported. Their [4+2] cycloadditions were efficiently catalyzed by IPrAuSbF6 (IPr=1,3‐bis(diisopropylphenyl)imidazol‐2‐ylidene) with high diastereoselectivity. Product analysis revealed that the reactions likely proceed by a stepwise ionic mechanism, because both E‐ and Z‐configured β‐methylstyrene gave the same cycloadducts in the same proportions. 相似文献
20.
Dr. Pavel Ryabchuk Thomas Leischner Dr. Carsten Kreyenschulte Dr. Anke Spannenberg Dr. Kathrin Junge Prof. Dr. Matthias Beller 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(42):18838-18844
A bifunctional 3d-metal catalyst for the cascade synthesis of diverse pyrroles from nitroarenes is presented. The optimal catalytic system Co/NGr-C@SiO2-L is obtained by pyrolysis of a cobalt-impregnated composite followed by subsequent selective leaching. In the presence of this material, (transfer) hydrogenation of easily available nitroarenes and subsequent Paal–Knorr/Clauson-Kass condensation provides >40 pyrroles in good to high yields using dihydrogen, formic acid, or a CO/H2O mixture (WGSR conditions) as reductant. In addition to the favorable step economy, this straightforward domino process does not require any solvents or external co-catalysts. The general synthetic utility of this methodology was demonstrated on a variety of functionalized substrates including the preparation of biologically active and pharmaceutically relevant compounds, for example, (+)-Isamoltane. 相似文献