共查询到20条相似文献,搜索用时 0 毫秒
1.
Synthesis of Strained γ‐Lactams by Palladium(0)‐Catalyzed C(sp3)−H Alkenylation and Application to Alkaloid Synthesis 下载免费PDF全文
Dr. Philipp M. Holstein David Dailler Julien Vantourout Janah Shaya Dr. Anthony Millet Prof. Dr. Olivier Baudoin 《Angewandte Chemie (International ed. in English)》2016,55(8):2805-2809
A variety of strained α‐alkylidene‐γ‐lactams were synthesized by palladium(0)‐catalyzed intramolecular C(sp3)?H alkenylation from easily accessible acyclic and monocyclic bromoalkene precursors. These lactams are valuable intermediates for accessing various classes of mono‐ and bicylic alkaloids containing a pyrrolidine ring, as illustrated with the synthesis of an advanced model of the marine natural product plakoridine A and of the indolizidine alkaloid δ‐coniceine. 相似文献
2.
Sebastian K. Kutz Dr. Carsten Börger Dr. Arndt W. Schmidt Prof. Dr. Hans‐Joachim Knölker 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(7):2487-2500
We describe the total synthesis of methylene‐bridged biscarbazole alkaloids by using a late‐stage Ullmann‐type coupling of fully functionalised carbazole subunits. The carbazole derivatives were synthesised via a sequence of palladium(0)‐ and palladium(II)‐catalysed coupling reactions. Our approach has provided bismurrayafoline‐A, bismurrayafolinol, chrestifolines B–D, and the first total synthesis of murrastifoline‐C and murrafoline‐E. 相似文献
3.
Total Synthesis of 7‐ and 8‐Oxygenated Pyrano[3,2‐a]carbazole and Pyrano[2,3‐a]carbazole Alkaloids via Boronic Acid‐Catalyzed Annulation of the Pyran Ring 下载免费PDF全文
Dr. Konstanze K. Julich‐Gruner Dr. Olga Kataeva Dr. Arndt W. Schmidt Prof. Dr. Hans‐Joachim Knölker 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(28):8536-8540
The boronic acid‐catalyzed annulation of citral opens up a short route to oxygenated cyclized monoterpenoid pyranocarbazole alkaloids. Thus, murrayamine‐D is available in only three steps and 55% overall yield from the corresponding carbazole precursor. 相似文献
4.
Back Cover: Total Synthesis of 7‐ and 8‐Oxygenated Pyrano[3,2‐a]carbazole and Pyrano[2,3‐a]carbazole Alkaloids via Boronic Acid‐Catalyzed Annulation of the Pyran Ring (Chem. Eur. J. 28/2014) 下载免费PDF全文
Dr. Konstanze K. Julich‐Gruner Dr. Olga Kataeva Dr. Arndt W. Schmidt Prof. Dr. Hans‐Joachim Knölker 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(28):8808-8808
5.
Ming Chen Feipeng Liu Prof.Dr. Guangbin Dong 《Angewandte Chemie (International ed. in English)》2018,57(14):3815-3819
A direct and catalytic method is reported here for β‐arylation of N‐protected lactams with simple aryl iodides. The transformation is enabled by merging soft enolization of lactams, palladium‐catalyzed desaturation, Ar?X bond activation, and aryl conjugate addition. The reaction is operated under mild reaction conditions, is scalable, and is chemoselective. Application of this method to concise syntheses of pharmaceutically relevant compounds is demonstrated. 相似文献
6.
Jayachandran Jayakumar Guganchandar Vedarethinam Huan‐Chang Hsiao Shang‐You Sun Shih‐Ching Chuang 《Angewandte Chemie (International ed. in English)》2020,59(2):689-694
Quaternary ammonium salts were synthesized in moderate to good yields through double oxidative C?H bond activation on azobenzenes. The mechanism of the highly regioselective reaction of 2‐azobiaryls with alkenes to give orange‐red‐fluorescent cinnolino[2,3‐f]phenanthridin‐9‐ium salts and 15H‐cinnolino[2,3‐f]phenanthridin‐9‐ium‐10‐ide is proposed to involve ortho C?H olefination of the 2‐azobiaryl compound with the alkene, intramolecular aza‐Michael addition, concerted metalation–deprotonation (CMD), reductive elimination, and oxidation. 相似文献
7.
Zhongxing Huang Chengpeng Wang Prof. Dr. Guangbin Dong 《Angewandte Chemie (International ed. in English)》2016,55(17):5299-5303
Described is a new hydrazone‐based exo‐directing group (DG) strategy developed for the functionalization of unactivated primary β C?H bonds of aliphatic amines. Conveniently synthesized from protected primary amines, the hydrazone DGs are shown to site‐selectively promote the β‐acetoxylation and tosyloxylation via five‐membered exo‐palladacycles. Amines with a wide scope of skeletons and functional groups are tolerated. Moreover, the hydrazone DG can be readily removed, and a one‐pot C?H acetoxylation/DG removal protocol was also discovered. 相似文献
8.
Synthesis of Prenyl‐ and Geranyl‐Substituted Carbazole Alkaloids by DIBAL‐H Promoted Reductive Pyran Ring Opening of Dialkylpyrano[3,2‐a]carbazoles 下载免费PDF全文
Ronny Hesse Dr. Olga Kataeva Dr. Arndt W. Schmidt Prof. Dr. Hans‐Joachim Knölker 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(31):9504-9509
The DIBAL‐H promoted reductive pyran ring opening of dialkylpyrano[3,2‐a]carbazoles provides a direct access to a broad range of prenyl‐ and geranyl‐substituted carbazoles. Formation of a pyran ring followed by reductive ring opening represents a new method for the introduction of prenyl and geranyl groups. In the course of the present work, we achieved the first total syntheses of the following eight carbazole alkaloids: clauraila‐E, 7‐hydroxyheptaphylline, 7‐methoxyheptaphylline, mukoenine‐B (clausenatine‐A), mukoenine‐A (girinimbilol), mahanimbinol (mahanimbilol), euchrestine‐A, and isomurrayafoline‐B. 相似文献
9.
Yi Ding Ye‐Qiang Han Le‐Song Wu Tao Zhou Qi‐Jun Yao Ya‐Lan Feng Ya Li Ke‐Xin Kong Bing‐Feng Shi 《Angewandte Chemie (International ed. in English)》2020,59(33):14060-14064
Herein, we describe an unprecedented cascade reaction to β‐stereogenic γ‐lactams involving Pd(II)‐catalyzed enantioselective aliphatic methylene C(sp3)?H alkenylation–aza‐Wacker cyclization through syn‐aminopalladation. Readily available 3,3′‐substituted BINOLs are used as chiral ligands, providing the corresponding γ‐lactams with broad scope and high enantioselectivities (up to 98 % ee). 相似文献
10.
Dr. Ryo Murakami Kentaro Sano Dr. Tomohiro Iwai Prof. Dr. Tohru Taniguchi Prof. Dr. Kenji Monde Prof. Dr. Masaya Sawamura 《Angewandte Chemie (International ed. in English)》2018,57(30):9465-9469
The palladium‐catalyzed asymmetric side‐chain C(α)‐allylation of 2‐alkylpyridines, without using an external base, was developed. The high linear selectivities and enantioselectivities were achieved using new chiral diamidophosphite monodentate ligands. Given that the reaction conditions do not require an external base, this catalyst system enabled chemoselective C(α)‐allylation of 2‐alkylpyridines containing α‐carbonyl C?H bonds, which are more acidic than α‐pyridyl C?H bonds. 相似文献
11.
Bijin Li Brianna Lawrence Guigen Li Haibo Ge 《Angewandte Chemie (International ed. in English)》2020,59(8):3078-3082
The first example of PdII‐catalyzed γ‐C(sp3)?H functionalization of aliphatic and benzoheteroaryl aldehydes has been developed using a transient ligand and an external ligand, concurrently. A wide array of γ‐arylated aldehydes were readily accessed without preinstalling internal directing groups. The catalytic mechanism was studied by performing deuterium‐labelling experiments, which indicated that the γ‐C(sp3)?H bond cleavage is the rate‐limiting step during the reaction process. This reaction could be performed on a gram scale, and also demonstrated its potential application in the synthesis of new mechanofluorochromic materials with blue‐shifted mechanochromic properties. 相似文献
12.
13.
Enantioselective C−H Olefination of α‐Hydroxy and α‐Amino Phenylacetic Acids by Kinetic Resolution 下载免费PDF全文
Dr. Kai‐Jiong Xiao Ling Chu Prof. Dr. Jin‐Quan Yu 《Angewandte Chemie (International ed. in English)》2016,55(8):2856-2860
Significant progress has been made in the past decade regarding the development of enantioselective C?H activation reactions by desymmetrization. However, the requirement for the presence of two chemically identical prochiral C?H bonds represents an inherent limitation in scope. Reported is the first example of kinetic resolution by a palladium(II)‐catalyzed enantioselective C?H activation and C?C bond formation, thus significantly expanding the scope of enantioselective C?H activation reactions. 相似文献
14.
Application of a Palladium‐Catalyzed C−H Functionalization/Indolization Method to Syntheses of cis‐Trikentrin A and Herbindole B 下载免费PDF全文
Raul A. Leal Caroline Bischof Youjin V. Lee Shota Sawano Christopher C. McAtee Luke N. Latimer Zachary N. Russ Prof. John E. Dueber Prof. Jin‐Quan Yu Prof. Richmond Sarpong 《Angewandte Chemie (International ed. in English)》2016,55(39):11824-11828
We describe herein formal syntheses of the indole alkaloids cis‐trikentrin A and herbindole B from a common meso‐hydroquinone intermediate prepared by a ruthenium‐catalyzed [2+2+1+1] cycloaddition that has not been used previously in natural product synthesis. Key steps include a sterically demanding Buchwald–Hartwig amination as well as a unique C(sp3)?H amination/indole formation. Studies toward a selective desymmetrization of the meso‐hydroquinone are also reported. 相似文献
15.
《化学:亚洲杂志》2017,12(18):2399-2403
An intramolecular exo ‐hydroarylation of 2‐aryloxy‐1,4‐disilylbut‐1‐en‐3‐ynes via ortho ‐C−H bond activation under palladium(0) and acid catalysis was found to give 2,3‐bis(silylmethylidene)‐2,3‐dihydrobenzofurans. The two silyl groups present probably promoted the reaction and played a key role in stabilizing the diene moiety in the product. The products readily led to functionalized condensed cycles by a Diels–Alder reaction. 相似文献
16.
Kiron Kumar Ghosh Alexander Uttry Arup Mondal Francesca Ghiringhelli Philipp Wedi Manuel van Gemmeren 《Angewandte Chemie (International ed. in English)》2020,59(31):12848-12852
We report the ligand‐enabled C?H activation/olefination of free carboxylic acids in the γ‐position. Through an intramolecular Michael addition, δ‐lactones are obtained as products. Two distinct ligand classes are identified that enable the challenging palladium‐catalyzed activation of free carboxylic acids in the γ‐position. The developed protocol features a wide range of acid substrates and olefin reaction partners and is shown to be applicable on a preparatively useful scale. Insights into the underlying reaction mechanism obtained through kinetic studies are reported. 相似文献
17.
Continuous‐Flow Synthesis and Derivatization of Aziridines through Palladium‐Catalyzed C(sp3)−H Activation 下载免费PDF全文
Jacek Zakrzewski Adam P. Smalley Dr. Mikhail A. Kabeshov Prof. Matthew J. Gaunt Prof. Alexei A. Lapkin 《Angewandte Chemie (International ed. in English)》2016,55(31):8878-8883
A continuous‐flow synthesis of aziridines by palladium‐catalyzed C(sp3)?H activation is described. The new flow reaction could be combined with an aziridine‐ring‐opening reaction to give highly functionalized aliphatic amines through a consecutive process. A predictive mechanistic model was developed and used to design the C?H activation flow process and illustrates an approach towards first‐principles design based on novel catalytic reactions. 相似文献
18.
Yinghua Yu Liyao Ma Jiajin Xia Luoting Xin Lei Zhu Xueliang Huang 《Angewandte Chemie (International ed. in English)》2020,59(41):18261-18266
Tricyclic ring systems possessing a dibenzo structure joined to a seven‐membered heterocyclic ring frequently show important biological activities. However, a modular approach to these molecules based on efficient intermolecular reaction of readily available chemicals is lacking. Herein, an unprecedented palladium‐catalyzed formal [4+3] annulation for modular construction of these tricyclic systems is described. This reaction features easily accessible reactants (o‐haloarylaldehydes and N‐tosylhydrazones), broad substrate scope, and excellent functional group compatibility. The synthetic potential is demonstrated by the easy scale‐up reactions, late‐stage modification of complex molecules, and collective synthesis of bioactive molecules and approved drugs. 相似文献
19.
Palladium‐Catalyzed γ‐C(sp3)−H Arylation of Thiols by a Detachable Protecting/Directing Group 下载免费PDF全文
Likun Jin Jianchun Wang Prof. Dr. Guangbin Dong 《Angewandte Chemie (International ed. in English)》2018,57(38):12352-12355
Reported herein is a palladium‐catalyzed, directed γ‐C(sp3)?H arylation of protected thiols. The key is to utilize Michael acceptors as a dual reagent to install a protecting/directing group on thiols by a thiol‐Michael click reaction, and remove it later under basic conditions. The C?H arylation proceeds with high functional‐group tolerance and the deprotected thiols can be further transformed into other sulfur‐containing compounds. This unique mode of activation could open the door for site‐selective functionalization of thiols or other sulfur‐containing compounds at unactivated positions. 相似文献
20.