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1.
Single‐Flask Multicomponent Palladium‐Catalyzed α,γ‐Coupling of Ketone Enolates: Facile Preparation of Complex Carbon Scaffolds 下载免费PDF全文
Michael Grigalunas Prof. Dr. Per‐Ola Norrby Prof. Dr. Olaf Wiest Prof. Dr. Paul Helquist 《Angewandte Chemie (International ed. in English)》2015,54(40):11822-11825
A three‐component palladium‐catalyzed reaction sequence has been developed in which γ‐substituted α,β‐unsaturated products are obtained in a single flask by an α‐alkenylation with either a subsequent γ‐alkenylation or γ‐arylation of a ketone enolate. Coupling of a variety of electronically and structurally different components was achieved in the presence of a Pd/Q‐Phos catalyst (2 mol %), usually at 22 °C with yields of up to 85 %. Most importantly, access to these products is obtained in one simple operation in place of employing multiple reactions. 相似文献
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Ting Zhao Katarzyna Kurpiewska Justyna Kalinowska‐Tłuścik Eberhardt Herdtweck Prof. Dr. Alexander Dömling 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(9):3009-3018
The synthesis of all 20 common natural proteinogenic and 4 otherα‐amino acid‐isosteric α‐amino tetrazoles has been accomplished, whereby the carboxyl group is replaced by the isosteric 5‐tetrazolyl group. The short process involves the use of the key Ugi tetrazole reaction followed by deprotection chemistries. The tetrazole group is bioisosteric to the carboxylic acid and is widely used in medicinal chemistry and drug design. Surprisingly, several of the common α‐amino acid‐isosteric α‐amino tetrazoles are unknown up to now. Therefore a rapid synthetic access to this compound class and non‐natural derivatives is of high interest to advance the field. 相似文献
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Copper‐Catalyzed Borocarbonylative Coupling of Internal Alkynes with Unactivated Alkyl Halides: Modular Synthesis of Tetrasubstituted β‐Borylenones 下载免费PDF全文
Li‐Jie Cheng Neal P. Mankad 《Angewandte Chemie (International ed. in English)》2018,57(32):10328-10332
Reported is a general procedure to synthesize tetrasubstituted enones, which are borylated in the β‐position, using a copper‐catalyzed four‐component coupling reaction of simple chemical feedstocks: internal alkynes, alkyl halides, bis(pinacolato)diboron (B2pin2), and CO. A broad scope of highly functionalized β‐borylated enones, a largely unknown class of organic compounds, can be accessed efficiently using this method. The synthesis of all‐carbon tetrasubstituted enones was realized by employing the β‐borylated enone unit, without purification, in a Suzuki–Miyaura coupling. The utility of the method was further demonstrated by various transformations, including halogenation, oxidation, and protodeboration, of the corresponding reduced oxaborole species to provide densely substituted allylic alcohol and ketone products. 相似文献
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Dr. Kaushik Chanda Sourav Rej Prof. Dr. Michael H. Huang 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(47):16036-16043
We report the highly facet‐dependent catalytic activity of Cu2O nanocubes, octahedra, and rhombic dodecahedra for the multicomponent direct synthesis of 1,2,3‐triazoles from the reaction of alkynes, organic halides, and NaN3. The catalytic activities of clean surfactant‐removed Cu2O nanocrystals with the same total surface area were compared. Rhombic dodecahedral Cu2O nanocrystals bounded by {110} facets were much more catalytically active than Cu2O octahedra exposing {111} facets, whereas Cu2O nanocubes displayed the slowest catalytic activity. The superior catalytic activity of Cu2O rhombic dodecahedra is attributed to the fully exposed surface Cu atoms on the {110} facet. A large series of 1,4‐disubstituted 1,2,3‐triazoles have been synthesized in excellent yields with high regioselectivity under green conditions by using these rhombic dodecahedral Cu2O catalysts, including the synthesis of rufinamide, an antiepileptic drug, demonstrating the potential of these nanocrystals as promising heterogeneous catalysts for other important coupling reactions. 相似文献
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Stereocontrolled Synthesis of syn‐β‐Hydroxy‐α‐Amino Acids by Direct Aldolization of Pseudoephenamine Glycinamide 下载免费PDF全文
Dr. Ian B. Seiple Jaron A. M. Mercer Robin J. Sussman Ziyang Zhang Prof. Dr. Andrew G. Myers 《Angewandte Chemie (International ed. in English)》2014,53(18):4642-4647
β‐Hydroxy‐α‐amino acids figure prominently as chiral building blocks in chemical synthesis and serve as precursors to numerous important medicines. Reported herein is a method for the synthesis of β‐hydroxy‐α‐amino acid derivatives by aldolization of pseudoephenamine glycinamide, which can be prepared from pseudoephenamine in a one‐flask protocol. Enolization of (R,R)‐ or (S,S)‐pseudoephenamine glycinamide with lithium hexamethyldisilazide in the presence of LiCl followed by addition of an aldehyde or ketone substrate affords aldol addition products that are stereochemically homologous with L ‐ or D ‐threonine, respectively. These products, which are typically solids, can be obtained in stereoisomerically pure form in yields of 55–98 %, and are readily transformed into β‐hydroxy‐α‐amino acids by mild hydrolysis or into 2‐amino‐1,3‐diols by reduction with sodium borohydride. This new chemistry greatly facilitates the construction of novel antibiotics of several different classes. 相似文献
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Synthesis of Diversely Functionalized Oxindoles Enabled by Migratory Insertion of Isocyanide to a Transient σ‐Alkylpalladium(II) Complex 下载免费PDF全文
Dr. Wangqing Kong Dr. Qian Wang Prof. Dr. Jieping Zhu 《Angewandte Chemie (International ed. in English)》2016,55(33):9714-9718
Palladium‐catalyzed intramolecular carbopalladation of N‐aryl acrylamides followed by migratory insertion of an isocyanide‐coordinated C(sp3)?Pd intermediate afforded an alkylimidoyl?PdII complex, which can be intercepted by a nucleophile, including heteroarenes. In addition to amides, the alkylimidoyl?PdII complex was successfully converted into esters, ketones, and bis‐heterocyclic compounds. An unprecedented palladium‐catalyzed enantioselective domino process involving isocyanide was also documented. 相似文献
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Enantioselective Palladium‐Catalyzed Oxidative β,β‐Fluoroarylation of α,β‐Unsaturated Carbonyl Derivatives 下载免费PDF全文
Javier Miró Dr. Carlos del Pozo Prof. F. Dean Toste Prof. Santos Fustero 《Angewandte Chemie (International ed. in English)》2016,55(31):9045-9049
The site‐selective palladium‐catalyzed three‐component coupling of deactivated alkenes, arylboronic acids, and N‐fluorobenzenesulfonimide is disclosed herein. The developed methodology establishes a general, modular, and step‐economical approach to the stereoselective β‐fluorination of α,β‐unsaturated systems. 相似文献
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Dr. Fabio Morana Dr. Andrea Basso Prof. Dr. Renata Riva Valeria Rocca Prof. Luca Banfi 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(14):4563-4569
A straightforward and fully stereoselective synthesis of a new class of peptidomimetics, that is α‐oxo‐γ‐acylaminoamides, was achieved starting from various benzaldehydes by a sequence of 1) an asymmetric organocatalytic Mannich reaction, 2) a Passerini multicomponent reaction, 3) an amine deprotection–acyl migration protocol, and 4) a final oxidation. The whole sequence can be performed without purification of the intermediates and represents the first example of a homo‐Passerini–amine deprotection–acyl migration (PADAM) strategy. Highly stereoselective reduction of the α‐oxo‐γ‐acylaminoamides afforded α‐hydroxy‐γ‐acylaminoamides as well. In some cases both diastereomers were obtained by simply changing the reducing agent. Finally, starting from protected salicylaldehyde, the same sequence, followed by a Mitsunobu cyclization, afforded highly substituted chromanes. 相似文献
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Highly Stereoselective Synthesis of Natural‐Product‐Like Hybrids by an Organocatalytic/Multicomponent Reaction Sequence 下载免费PDF全文
M. Sc. Radell Echemendía M. Sc. Alexander F. de La Torre M. Sc. Julia L. Monteiro M. Sc. Michel Pila Prof. Dr. Arlene G. Corrêa Prof. Dr. Bernhard Westermann Prof. Dr. Daniel G. Rivera Prof. Dr. Márcio W. Paixão 《Angewandte Chemie (International ed. in English)》2015,54(26):7621-7625
In an endeavor to provide an efficient route to natural product hybrids, described herein is an efficient, highly stereoselective, one‐pot process comprising an organocatalytic conjugate addition of 1,3‐dicarbonyls to α,β‐unsaturated aldehydes followed by an intramolecular isocyanide‐based multicomponent reaction. This approach enables the rapid assembly of complex natural product hybrids including up to four different molecular fragments, such as hydroquinolinone, chromene, piperidine, peptide, lipid, and glycoside moieties. The strategy combines the stereocontrol of organocatalysis with the diversity‐generating character of multicomponent reactions, thus leading to structurally unique peptidomimetics integrating heterocyclic, lipidic, and sugar moieties. 相似文献
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Oxidative Asymmetric Aza‐Friedel–Crafts Alkylation of Indoles with 3‐Indolinone‐2‐carboxylates Catalyzed by a BINOL Phosphoric Acid and Promoted by DDQ 下载免费PDF全文
An asymmetric aza‐Friedel–Crafts alkylation reaction between indoles and indolenines that were derived in situ from 3‐indolinone‐2‐carboxylates has been developed by using 3,3′‐bis(triphenylsilyl)‐1,1′‐binaphthyl‐2,2′‐diyl hydrogen phosphate as a catalyst. The reaction proceeded under mild conditions and provided chiral indol‐3‐yl‐3‐indolinone‐2‐carboxylate derivatives in good yields with excellent ee values (up to 98.6 %). Similarly, the Mannich‐type addition of indoline‐3‐ones to indolenines provided heterodimers with vicinal chiral quaternary centers. This method was successfully applied to the construction of the core structure of trigonoliimine C. 相似文献
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Direct Synthesis of Benzofuro[2,3‐b]pyrroles through a Radical Addition/[3,3]‐Sigmatropic Rearrangement/Cyclization/Lactamization Cascade 下载免费PDF全文
Dr. Masafumi Ueda Yuta Ito Yuki Ichii Maiko Kakiuchi Hiroko Shono Prof. Dr. Okiko Miyata 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(22):6763-6770
A straightforward synthetic method for the construction of benzofuro[2,3‐b]pyrrol‐2‐ones by a novel domino reaction through a radical addition/[3,3]‐sigmatropic rearrangement/cyclization/lactamization cascade has been developed. The domino reaction of O‐phenyl‐conjugated oxime ether with an alkyl radical allows the construction of two heterocycles with three stereogenic centers as a result of the formation of two C?C bonds, a C?O bond, and a C?N bond in a single operation, leading to pyrrolidine‐fused dihydrobenzofurans, which are not easily accessible by existing synthetic methods. Furthermore, asymmetric synthesis of benzofuro[2,3‐b]pyrrol‐2‐one derivatives through a diastereoselective radical addition reaction to a chiral oxime ether was also developed. 相似文献
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The multicomponent reactions of aldehydes, electron deficient alkynes and amines have been successfully performed to yield a number of symmetrical 2,6‐unsubstituted 1,4‐dihydropyridines (1,4‐DHPs). This method has been found generally applicable for the synthesis of both N‐substituted and N‐unsubstituted 1,4‐DHPs by employing secondary amine to activate the alkyne component via enaminoester intermediates. The present method runs through an enamine type activation, which is different from the known approach employing AcOH as solvent. 相似文献
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Bidyut Kumar Senapati Dr. Geum‐Sook Hwang Prof. Dr. Sungil Lee Do Hyun Ryu Prof. Dr. 《Angewandte Chemie (International ed. in English)》2009,48(24):4398-4401
A catalytic route toward chiral Morita–Baylis–Hillman esters by asymmetric coupling between α,β‐acetylenic esters, aldehydes, and trimethylsilyl iodide has been developed (see scheme). The reaction proceeds with high to excellent enantioselectivities, and the products can be transformed into β‐branched derivatives in a single step and with excellent retention of configuration. TMS=trimethylsilyl
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Xiaodong Jia Xiangning Chen Congde Huo Fangfang Peng Chang Qing Xicun Wang 《中国化学》2012,30(7):1504-1510
A multicomponent double Mannich reaction of amines, aldehydes and ketones was efficiently catalyzed by molecular iodine, producing a series of 4‐piperidones in a stereoselective way. A variety of amines, aldehydes and ketones were tolerated in this tandem process, including those with labile functinal groups. Further investigation of the reaction between alkyl‐imines and ketones showed that imines from amines and ketones were formed in situ and isomerized to enamine in the presence of molecular iodine to accelerate the corresponding Mannich addition. 相似文献
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A simple, efficient and eco‐friendly route has been developed for the synthesis of β‐mercapto diketones via a multicomponent reaction of an aldehyde, acetylacetone and thiol in water. This methodology affords a number of β‐mercapto diketone derivatives in moderate to good yields. 相似文献