共查询到20条相似文献,搜索用时 31 毫秒
1.
Asimina Bourboula Olga G. Mountanea George Krasakis Dr. Christiana Mantzourani Prof. Dr. Maroula G. Kokotou Prof. Dr. Christoforos G. Kokotos Prof. Dr. George Kokotos 《European journal of organic chemistry》2023,26(24):e202300008
In recent years, the development of light-mediated methods for synthetic applications has attracted high interest, because such methods constitute alternative approaches for the production of valuable chemical products. We study herein a photochemical protocol for the synthesis of Weinreb amides and morpholine amides from carboxylic acids. Various carboxylic acids were directly coupled to N,O-dimethylhydroxylamine, upon irradiation with either LED 370 nm or sunlight in the presence of 4-dimethylaminopyridine and bromotrichloromethane, providing Weinreb amides in moderate to high yields. Similarly, morpholine amides were obtained in satisfactory to high yields under sunlight or LED 370 nm irradiation. Thus, the versatile building blocks Weinreb amides and morpholine amides may be efficiently synthesized directly from carboxylic acids by light-mediated approaches, without the need of coupling reagents or pre-activation of carboxylic acids. 相似文献
2.
Yong Luo Hao Ding Jing-Song Zhen Xian Du Xiao-Hong Xu Han Yuan Yi-Hui Li Wan-Ying Qi Bing-Zhe Liu Shi-Man Lu Can Xue Qiuping Ding 《Chemical science》2021,12(27):9556
A novel arylation of sulfonamides with boronic acids to afford numerous diaryl sulfones via a visible light-mediated N–S bond cleavage other than the typical transition-metal-catalyzed C(O)–N bond activation is described. This methodology, which represents the first catalyst-free protocol for the sulfonylation of boronic acids, is characterized by its simple reaction conditions, good functional group tolerance and high efficiency. Several successful examples for the late-stage functionalization of diverse sulfonamides indicate the high potential utility of this method in pharmaceutical science and organic synthesis.The simple, catalyst-free sulfonylation of boronic acids with sulfonamides via a visible light-mediated N–S bond cleavage is described, affording diaryl sulfones with high efficiency. Late-stage functionalization of sulfonamide drugs was shown. 相似文献
3.
Céderic Ver Elst Dr. Robby Vroemans Mathias Bal Dr. Sergey Sergeyev Dr. Carl Mensch Prof. Dr. Bert U. W. Maes 《Angewandte Chemie (International ed. in English)》2023,62(46):e202309597
Levulinic acid is a key biorenewable platform molecule. Its current chemical production from sugars is plagued by limited yields, char formation and difficult separations. An alternative and selective route starting from muconic acid via simple heating in water at high temperature (180 °C) has been developed. Muconic acid can be obtained from sugars or catechol fermentation. Chemical oxidation of catechol is another possibility which advantageously can also be applied on substituted catechols, hereby providing substituted muconic acids. When applying the disclosed hydrothermal protocol on these substrates hitherto unknown substituted levulinic acids were accessed. In particular, 3-propyllevulinic acid has been synthesized from 4-propylcatechol, prepared from pine wood. This propylated derivative has been used for the synthesis of a 3-propyllevulinate diester, i.e. butane-1,4-diyl bis(4-oxo-3-propylpentanoate), via esterification with 1,4-butanediol. The diester showed superior performance as plasticizer in comparison to the corresponding levulinate diester in both PVC (polyvinyl chloride) and PLA (polylactic acid). It plasticizes equally effective as the notorious commercial phthalate-based benchmark DEHP (di-2-ethylhexyl phthalate) in PVC. 相似文献
4.
Hua-Chao Liu Yuan-Zheng Hu Zuo-Fei Wang Hai-Yan Tao Prof. Dr. Chun-Jiang Wang 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(37):8681-8685
An unprecedented asymmetric allenylic alkylation of readily available imine esters, which was enabled by a synergistic Cu/Pd catalysis, has been developed. This dual catalytic system possesses good substrate compatibility, delivering a diverse array of nonproteinogenic α-allenylic α-mono- or α,α-disubstituted α-amino acids (α-AAs) with high yields and generally excellent enantioselectivities. Furthermore, the scalability and practicability of the current synthetic protocol were proven by performing gram-scale reactions and by the first catalytic asymmetric synthesis of naturally occurring (S)-γ-allenic α-amino acid, respectively. 相似文献
5.
Du Chen Liangxuan Xu Yi Yu Qinliang Mo Xiaotian Qi Prof. Dr. Chao Liu 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2023,135(2):e202215168
Building up new and efficient methods for the controlled conversion of carboxylic acids to aldehydes is important. Herein, we report a rapid, modular and scalable method for the conversion of carboxylic acids to aldehydes using pinacolborane at ambient temperature, in which a triflylpyridinium reagent is used. The conversion of carboxylic acid to intermediate acylpyridinium by triflylpyridinium is new. A binary pyridine-coordinated boronium complex is generated after reduction. The unprecedented reduction of the acylpyridinium by HBpin opens up a practically direct synthesis of aldehydes from carboxylic acids. Theoretical studies indicate that the reduction of acylpyridinium requires a lower activation free energy than that of the product aldehyde. The synthetic advantage of this protocol is further highlighted by the scalable synthesis of aldehyde via continuous flow process. Configuration retention for chiral acids are presented in those syntheses. 相似文献
6.
A novel and efficient procedure was developed for direct preparation of aryl‐substituted lactones from corresponding aryl‐substituted alkanoic acids, catalyzed by the in situ generated hypervalent iodine intermediate from iodobenzene (PhI). In this protocol, aryl‐substituted alkanoic acids were treated with m‐chloroperbenzoic acid (mCPBA) and KBr in the presence of a catalytic amount of PhI in 2,2,2‐trifluoroethanol at room temperature for 24 h, resulting in corresponding aryl lactones in moderate‐to‐good yields. 相似文献
7.
Jonas Rydfjord Fredrik Svensson Dr. Alejandro Trejos Dr. Per J. R. Sjöberg Dr. Christian Sköld Dr. Jonas Sävmarker Dr. Luke R. Odell Prof. Dr. Mats Larhed 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(41):13803-13810
A fast and convenient synthesis of aryl amidines starting from carboxylic acids and cyanamides is reported. The reaction was achieved by palladium(II)‐catalysis in a one‐step microwave protocol using [Pd(O2CCF3)2], 6‐methyl‐2,2′‐bipyridyl and trifluoroacetic acid (TFA) in N‐methylpyrrolidinone (NMP), providing the corresponding aryl amidines in moderate to excellent yields. The protocol is very robust with regards to the cyanamide coupling partner but requires electron‐rich ortho‐substituted aryl carboxylic acids. Mechanistic insight was provided by a DFT investigation and direct ESI‐MS studies of the reaction. The results of the DFT study correlated well with the experimental findings and, together with the ESI‐MS study, support the suggested mechanism. Furthermore, a scale‐out (scale‐up) was performed with a non‐resonant microwave continuous‐flow system, achieving a maximum throughput of 11 mmol h?1 by using a glass reactor with an inner diameter of 3 mm at a flow rate of 1 mL min?1. 相似文献
8.
Dr. Michele Retini Dr. Silvia Bartolucci Dr. Francesca Bartoccini Prof. Giovanni Piersanti 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(57):e202201994
The growing importance of structurally diverse and functionalized enantiomerically pure unnatural amino acids in the design of drugs, including peptides, has stimulated the development of new synthetic methods. This study reports the challenging direct asymmetric alkylation of cyclic ketones with dehydroalanine derivatives via a conjugate addition reaction for the synthesis of enantiopure ketone-based α-unnatural amino acids. The key to success was the design of a bifunctional primary amine-thiourea catalyst that combines H-bond-directing activation and enamine catalysis. The simultaneous dual activation of the two relatively unreactive partners, confirmed by mass spectrometry studies, results in high reactivity while securing high levels of stereocontrol. A broad substrate scope is accompanied by versatile downstream chemical modifications. The mild reaction conditions and consistently excellent enantioselectivities (>95 % ee in most cases) render this protocol highly practical for the rapid construction of valuable noncanonical enantiopure α-amino-acid building blocks. 相似文献
9.
Stereocontrolled Synthesis of syn‐β‐Hydroxy‐α‐Amino Acids by Direct Aldolization of Pseudoephenamine Glycinamide
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. 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
10.
含氟β-氨基酸及其衍生物具有特殊的生理活性, 其合成方法的研究近年来受到广泛关注. 以直接氟化法和间接氟化法分类, 概述了含氟β-氨基酸及其衍生物的合成方法及最新研究进展, 对一些已知化合物的生理活性及药用价值作了初步归纳. 相似文献
11.
Directly Bridging Indoles to 3,3′‐Bisindolylmethanes by Using Carboxylic Acids and Hydrosilanes under Mild Conditions
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)
《化学:亚洲杂志》2018,13(18):2664-2670
A straightforward Lewis acid‐promoted protocol for 3,3′‐bisindolylmethanes (BIMs) synthesis by reductive alkylation of indoles at the C3 position with carboxylic acids in the presence of hydrosilane was developed for the first time. Instead of aldehydes, more readily available, stable, and easy‐to‐handle carboxylic acids have been employed as alternative alkylating agents. As an efficient organocatalyst, B(C6F5)3 enables the reductive alkylation of various substituted indole derivatives with carboxylic acids with up to 98 % yield at room temperature and under neat conditions. This metal‐free strategy offers an alternative approach for the direct functionalization of indoles to BIMs with carboxylic acids and such protocol allows selective reduction of carboxylic acid to aldehyde in combination with C−C bond formation. 相似文献
12.
An improved procedure for the asymmetric synthesis of α-aminoalkylphosphonic acids using S-2-anilinomethylpyrrolidine as the chiral auxiliary was described. The chemical transformations involved in this protocol could proceed under mild reaction condition to provide good chemical and enantiomeric yields. 相似文献
13.
David M. Whalley Hung A. Duong Prof. Michael F. Greaney 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(8):1927-1930
A light-mediated Truce–Smiles arylative rearrangement is described that proceeds in the absence of any photocatalyst. The protocol creates two C−C bonds from simple starting materials, with the installation of an aryl ring and a difluoroacetate moiety across unactivated alkenes. The reaction proceeds via a radical mechanism, utilizing a light-mediated reduction of ethyl bromodifluoroacetate by N,N,N′,N′-tetramethylethylenediamine (TMEDA) to set up intermolecular addition to an unactivated alkene, followed by Truce–Smiles rearrangement. 相似文献
14.
A straightforward synthesis of orthogonally protected nucleoproline (Nup) amino acids and their coupling to oligomers are described. A key step is the attachment of alkynylated nucleobases to Fmoc‐protected 4‐azidoproline (Fmoc‐Azp‐OH) by a Cu‐catalyzed 1,3‐dipolar cycloaddition (‘click reaction’). The developed protocol allows preparation of the nucleoprolines in scales of >30 g. Solid‐phase peptide synthesis proved to be straightforward with these Nup amino acids. The resulting oligonucleoproline peptides adopt defined helices, are very well H2O soluble, and show comparable cell‐penetrating properties as recently reported α‐nucleoalanine peptides. 相似文献
15.
Unsaturated nitro fatty acids (NO2-FAs) constitute a category of molecules that may be formed endogenously by the reaction of unsaturated fatty acids (UFAs) with secondary species of nitrogen monoxide and nitrite anions. The warhead of NO2-FAs is a nitroalkene moiety, which is a potent Michael acceptor and can undergo nucleophilic attack from thiol groups of biologically relevant proteins, showcasing the value of these molecules regarding their therapeutic potential against many diseases. In general, NO2-FAs inhibit nuclear factorκ-B (NF-κB), and simultaneously they activate nuclear factor (erythroid derived)-like 2 (Nrf2), which activates an antioxidant signaling pathway. NO2-FAs can be synthesized not only endogenously in the organism, but in a synthetic laboratory as well, either by a step-by-step synthesis or by a direct nitration of UFAs. The step-by-step synthesis requires specific precursor compounds and is in position to afford the desired NO2-FAs with a certain position of the nitro group. On the contrary, the direct nitration of UFAs is not a selective methodology; thus, it affords a mixture of all possible nitro isomers. 相似文献
16.
Vadiga Shanthi Kumar Veera Babu Gudise Eeda Koti Reddy Shaik Anwar 《Journal of heterocyclic chemistry》2019,56(10):2753-2760
An efficient protocol has been developed for the synthesis of 2‐oxazolines from carboxylic acids and silylated amino alcohols. The advantage of this method was demonstrated by preparing O‐silylated amino alcohols. The reaction proceeds via in situ desilylation of O‐silylated amide followed by cyclization. Studies on silyl deprotection were carried out to explain yield for 2‐oxazolines. 相似文献
17.
Rehanguli Ruzi Junyang Ma Prof. Dr. Xiang-Ai Yuan Wenliang Wang Shanshan Wang Dr. Muliang Zhang Dr. Jie Dai Prof. Dr. Jin Xie Prof. Dr. Chengjian Zhu 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(55):12724-12729
An unprecedented deoxygenative arylation of aromatic carboxylic acids has been achieved, allowing the construction of an enhanced library of unsymmetrical diaryl ketones. The synergistic photoredox catalysis and phosphoranyl radical chemistry allows for precise cleavage of a stronger C−O bond and formation of a weaker C−C bond by 1,5-aryl migration under mild reaction conditions. This new protocol is independent of substrate redox-potential, electronic, and substituent effects. It affords a general and promising access to 60 examples of synthetically versatile o-amino and o-hydroxy diaryl ketones under redox-neutral conditions. Furthermore, it also brings one concise route to the total synthesis of quinolone alkaloid, (±)-yaequinolone A2, and a viridicatin derivative in satisfying yields. 相似文献
18.
An Enantioselective Assembly of Dihydropyranones through an NHC/LiCl‐Mediated in situ Activation of α,β‐Unsaturated Carboxylic Acids
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)
Yonglei Que Yinan Lu Wenjing Wang Yuhong Wang Haotian Wang Chenxia Yu Tuanjie Li Xiang‐Shan Wang Shide Shen Changsheng Yao 《化学:亚洲杂志》2016,11(5):678-681
A straightforward N‐heterocyclic carbene (NHC)/LiCl‐mediated synthesis of dihydropyranones from α,β‐unsaturated carboxylic acids and 1,3‐dicarbonyl compounds was realized through the in situ activation strategy. The key advantages of this protocol include ready availability and high stability of starting materials, good yields, and excellent enantioselectivity. 相似文献
19.
Practical Synthesis of anti‐β‐Hydroxy‐α‐Amino Acids by PdII‐Catalyzed Sequential C(sp3)H Functionalization
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)
Kai Chen Shuo‐Qing Zhang Huai‐Zhi Jiang Jing‐Wen Xu Prof. Dr. Bing‐Feng Shi 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(8):3264-3270
An improved and practical procedure for the stereoselective synthesis of anti‐β‐hydroxy‐α‐amino acids (anti‐βhAAs), by palladium‐catalyzed sequential C(sp3)?H functionalization directed by 8‐aminoquinoline auxiliary, is described. followed by a previously established monoarylation and/or alkylation of the β‐methyl C(sp3)?H of alanine derivative, β‐acetoxylation of both alkylic and benzylic methylene C(sp3)?H bonds affords various anti‐β‐hydroxy‐α‐amino acid derivatives. As an example, the synthesis of β‐mercapto‐α‐amino acids, which are highly important to the extension of native chemical ligation chemistry beyond cysteine, is described. The synthetic potential of this protocol is further demonstrated by the synthesis of diverse β‐branched α‐amino acids. The observed diastereoselectivities are strongly influenced by electronic effects of aromatic AAs and steric effects of the linear side‐chain AAs, which could be explained by the competition of intramolecular C?OAc bond reductive elimination from PdIV intermediates vs. intermolecular attack by an external nucleophile (AcO?) in an SN2‐type process. 相似文献
20.
Ning‐Xin Xu Bi‐Xiao Li Chao Wang Masanobu Uchiyama 《Angewandte Chemie (International ed. in English)》2020,59(26):10639-10644
Silicon‐containing compounds are widely used as synthetic building blocks, functional materials, and bioactive reagents. In particular, silyl radicals are important intermediates for the synthesis and transformation of organosilicon compounds. Herein, we describe the first protocol for the generation of silyl radicals by photoinduced decarboxylation of silacarboxylic acids, which can be easily prepared in high yield on a gram scale and are very stable to air and moisture. Irradiation of silacarboxylic acids with blue LEDs (455 nm) in the presence of a commercially available photocatalyst releases silyl radicals, which can further react with various alkenes to give the corresponding silylated products in good‐to‐high yields with broad functional‐group compatibility. This reaction proceeds in the presence of water, enabling efficient deuterosilylation of alkenes with D2O as the deuterium source. Germyl radicals were similarly obtained. 相似文献