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1.
(E)‐,(Z)‐Parallel Preparative Methods for Stereodefined β,β‐Diaryl‐ and α,β‐Diaryl‐α,β‐unsaturated Esters: Application to the Stereocomplementary Concise Synthesis of Zimelidine
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Yuichiro Ashida Yuka Sato Takeyuki Suzuki Kanako Ueno Ken‐ichiro Kai Dr. Hidefumi Nakatsuji Prof. Dr. Yoo Tanabe 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(15):5934-5945
Parallel and practical methods for the preparation of both (E)‐ and (Z)‐β‐aryl1‐β‐aryl2‐α,β‐unsaturated esters 1 and (E)‐ and (Z)‐α‐aryl1‐β‐aryl2‐α,β‐unsaturated esters 2 are described. These methods involve accessible, robust, stereocomplementary N‐methylimidazole (NMI)‐mediated enol tosylations (14 examples, 70–99 % yield), as well as stereoretentive Suzuki–Miyaura cross‐couplings (36 examples, 64–99 % yield). The highlighted feature of the present protocol is the use of parallel and stereocomplementary approaches to obtain highly (E)‐ and (Z)‐pure products 1 and 2 by utilizing sequential enol tosylations and cross‐coupling reactions. An expeditious and parallel synthesis of (E)‐ and (Z)‐zimelidine ( 3 ), which is a highly representative selective serotonin reuptake inhibitor (SSRI), was performed by utilizing the present methods. 相似文献
2.
(E)‐α,β‐Unsaturated pyrazoleamides undergo facile dienolization to furnish copper(I)‐(1Z,3Z)‐dienolates as the major in the presence of a copper(I)‐(R)‐DTBM‐SEGPHOS catalyst and Et3N, which react with aldimines to afford syn‐vinylogous products as the major diastereoisomers in high regio‐ and enantioselectivities. In some cases, the diastereoselectivity is low, possibly due to the low ratio of copper(I)‐(1Z,3Z)‐dienolates to copper(I)‐(1Z,3E)‐dienolates. (Z)‐Allylcopper(I) species is proposed as effective intermediates, which may form an equilibrium with copper(I)‐(1Z,3Z)‐dienolates. Interestingly, the present methodology is a nice complement to our previous report, in which (E)‐β,γ‐unsaturated pyrazoleamides were employed as the prenucleophiles in the copper(I)‐catalyzed asymmetric vinylogous Mannich‐Type reaction and anti‐vinylogous products were obtained. In the previous reaction, copper(I)‐ (1Z,3E)‐dienolates were generated through α‐deprotonation, which might form an equilibrium with (E)‐allylcopper(I) species. Therefore, it is realized in the presence of a copper(I) catalyst that (E)‐α,β‐unsaturated pyrazoleamides lead to syn‐products and (E)‐β,γ‐unsaturated pyrazoleamides lead to anti‐products. Finally, by use of (E)‐β,γ‐unsaturated pyrazoleamide, (E)‐α,β‐unsaturated pyrazoleamide, (R)‐DTBM‐SEGPHOS, and (S)‐DTBM‐SEGPHOS, the stereodivergent synthesis of all four stereoisomers is successfully carried out. Then by following a three‐step reaction sequence, all four stereoisomers of N‐Boc‐2‐Ph‐3‐Me‐piperidine are synthesized in good yields, which potentially serve as common structure units in pharmaceutically active compounds. 相似文献
3.
Thermal Arndt–Eistert reactions of N‐tosyl cyclic α‐amino acids were studied to explore the preparation of α,β‐unsaturated esters bearing a terminal tosylamino group. For L‐N‐tosyl‐aziridine 2‐carboxylic acid and L‐N‐tosyl‐azetidine 2‐carboxylic acid, the corresponding (E)‐α,β‐unsaturated esters were obtained stereospecifically. 相似文献
4.
β‐Bromo‐α,β‐unsaturated amides are coupled and cyclized with terminal alkynes in DMF at 110 °C in the presence of a catalytic amount of CuI and amino acid along with a base to give the corresponding (3Z)‐3‐alkylidenepyrrol‐1‐ones in moderate to good yields. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
5.
Lingjian Zhu Ning Lei Zhenyuan Miao Chunquan Sheng Chunlin Zhuang Jianzhong Yao Wannian Zhang 《中国化学》2012,30(1):139-143
A mild and efficient Knoevenagel‐Doebner reaction from malonic acid and a wide range of aldehydes was catalyzed by a catalytic system consisting of β‐alanine and 1,8‐diazabicyclo[5.4.0]undec‐7‐ene (DBU), affording the corresponding (E)‐α,β‐unsaturated carboxylic acids in good to excellent yields and with high stereoselectivity. The advantage of the method is that the reaction could proceed smoothly at ambient temperature so that it can tolerate a variety of functional groups and avoid unnecessary side reactions. 相似文献
6.
Palladium‐catalyzed carbonylative cyclization of β‐bromo‐α,β‐unsaturated carboxylic acids with 2,2‐dimethylhydrazine leading to 1‐(dimethylamino)‐1H‐pyrrole‐2,5‐diones
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β‐Bromo‐α,β‐unsaturated carboxylic acids are carbonylatively cyclized with 2,2‐dimethylhydrazine under carbon monoxide pressure in THF in the presence of a catalytic amount of a palladium catalyst along with a base to give 1‐(dimethylamino)‐1H‐pyrrole‐2,5‐diones. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
7.
A tandem IBX‐promoted oxidation of primary alcohol to aldehyde and opening of intermediate β,γ‐diolcarbonate aldehyde to (E)‐γ‐hydroxy‐α,β‐enal has been developed. Remarkably, the carbonate opening delivered exclusively (E)‐olefin and no over‐oxidation of γ‐hydroxy was observed. The method developed has been extended to complete the stereoselective total synthesis of both (S)‐ and (R)‐coriolides and d ‐xylo‐ and d ‐arabino‐C‐20 guggultetrols. 相似文献
8.
Cyclic β‐bromo‐α,β‐unsaturated carboxylic acids are carbonylatively cyclized with primary amines under carbon monoxide pressure in MeCN in the presence of a catalytic amount of PdCl2(PPh3)2 to give N‐alkylmaleimides. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
9.
Treatment of 3‐methylamino‐5‐phenylthiophene with α,β‐unsaturated esters, i.e., methyl acrylate, (E)‐methyl crotonate, diethyl fumarate, diethyl maleate and ethyl propiolate, in tetrahydrofuran for several days at reflux gave 1‐methyl‐3,4‐dihydrothieno[2,3‐e]pyridin‐2‐ones 4 and/or 1‐methylthieno[2,3‐e]pyridin‐2‐ones 5 , depending on the structure of the esters. On the other hand, the same reactions with α,β‐unsaturated nitriles such as acrylonitrile and tetracyanoethene, gave the corresponding thiophenes 7 and 10 bearing 2‐cyanoethyl and 1,2,2‐tricyanoethenyl groups at C‐2, respectively. The reaction with (Z)‐1,2‐dicyanoethene under the same conditions produced the corresponding thiophene 9 bearing the 1,2‐dicyanoethenyl group and 1,2‐dicyano‐5‐methylaminobiphenyl. 相似文献
10.
Iridium‐Catalyzed Annulation Reactions of Thiophenes with Carboxylic Acids: Direct Evidence for a Heck‐type Pathway
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Guangying Tan Qiulin You Prof. Dr. Jingbo Lan Prof. Dr. Jingsong You 《Angewandte Chemie (International ed. in English)》2018,57(21):6309-6313
The functionalization of thiophenes is a fundamental and important reaction. Herein, we disclose iridium‐catalyzed one‐pot annulation reactions of (benzo)thiophenes with (hetero)aromatic or α,β‐unsaturated carboxylic acids, which afford thiophene‐fused coumarin‐type frameworks. Dearomatization reactions of 2‐substituted thiophenes with α,β‐unsaturated carboxylic acids deliver various thiophene‐containing spirocyclic products. The occurrence of two interconnected reactions provides direct evidence for a Heck‐type pathway. The mechanistic scenario described herein is distinctly different from the SEAr and concerted metalation–protodemetalation (CMD) pathways encountered in the well‐described oxidative C?H/C?H cross‐coupling reactions of thiophenes with other heteroarenes. 相似文献
11.
Treatment of α,β‐unsaturated ketones with an electrophilic site at the γ‐position in the presence of trimethylsilyl cyanide with bis(iodozincio)methane afforded the (Z)‐silyl enol ether of the β‐cyclopropyl substituted ketone in good yields. The reaction proceeds by 1,4‐addition to form an enolate, and its sequential intramolecular nucleophilic attack to an adjacent electrophilic site. The reaction of γ‐ethoxycarbonyl‐α,β‐unsaturated ketone and bis(iodozincio)methane in the presence of trimethylsilyl cyanide afforded 1‐ethoxy‐1‐trimethylsiloxycyclopropane derivatives, which can be regarded as the homoenolate equivalent. Additionally, reaction of the obtained homoenolate equivalents with imines give 1‐(E)‐alkenyl‐2‐(1‐aminoalkyl)alkanols diastereoselectively. 相似文献
12.
Divergent Pathways and Competitive Mechanisms of Metathesis Reactions between 3‐Arylprop‐2‐ynyl Esters and Aldehydes: An Experimental and Theoretical Study
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Dr. Cristina Trujillo Dr. Goar Sánchez‐Sanz Ieva Karpavičienė Dr. Ullrich Jahn Dr. Inga Čikotienė Dr. Lubomír Rulíšek 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(33):10360-10370
Mechanistic studies of the reaction between 3‐arylprop‐2‐ynyl esters and aldehydes catalyzed by BF3 ? Et2O were performed by isotopic labeling experiments and quantum chemical calculations. The reactions are shown to proceed by either a classical alkyne–carbonyl metathesis route or an unprecedented addition–rearrangement cascade. Depending on the structure of the starting materials and the reaction conditions, the products of these reactions can be Morita–Baylis–Hillman (MBH) adducts that are unavailable by traditional MBH reactions or E‐ and Z‐α,β‐unsaturated ketones. 18O‐Labeling studies suggested the existence of two different reaction pathways to the products. These pathways were further examined by quantum chemical calculations that employed the DFT(wB97XD)/6‐311+G(2d,p) method, together with the conductor‐like screening model for realistic solvation (COSMO‐RS). By using the wB97XD functional, the accuracy of the computed data is estimated to be 1–2 kcal mol?1, shown by the careful benchmarking of various DFT functionals against coupled cluster calculations at the CCSD(T)/aug‐cc‐pVTZ level of theory. Indeed, most of the experimental data were reproduced and explained by theory and it was convincingly shown that the branching point between the two distinct mechanisms is the formation of the first intermediate on the reaction pathway: either the four‐membered oxete or the six‐membered zwitterion. The deep mechanistic understanding of these reactions opens new synthetic avenues to chemically and biologically important α,β‐unsaturated ketones. 相似文献
13.
(E)‐α‐Arylsulfanylvinylstannanes react with acyl halides in the presence of a catalytic amount of Pd(PPh3)4 and CuI cocatalyst to give stereoselectively the corresponding (Z)‐α‐arylsulfanyl‐α,β‐unsaturated ketones in good yields. © 2009 Wiley Periodicals, Inc. Heteroatom Chem 20:218–223, 2009; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20536 相似文献
14.
Palladium‐catalyzed decarboxylative coupling of α,β‐unsaturated carboxylic acids with aryl tosylates
We report a general method for selective cross‐coupling of α,β‐unsaturated carboxylic acids with aryl tosylates enabled by versatile Pd(II) complexes. This method features the general cross‐coupling of ubiquitous α,β‐unsaturated carboxylic acids by decarboxylation. The transformation is characterized by its operational simplicity, the use of inexpensive, air‐stable Pd(II) catalysts, scalability and wide substrate scope. The reaction proceeds with high trans selectivity to furnish valuable (E)‐1,2‐diarylethenes. 相似文献
15.
《Chemistry (Weinheim an der Bergstrasse, Germany)》2006,12(1):63-71
New asymmetric conjugate reduction of β,β‐disubstituted α,β‐unsaturated ketones and esters was accomplished with alkoxylhydrosilanes in the presence of chiral rhodium(2,6‐bisoxazolinylphenyl) complexes in high yields and high enantioselectivity. (E)‐4‐Phenyl‐3‐penten‐2‐one and (E)‐4‐phenyl‐4‐isopropyl‐3‐penten‐2‐one were readily reduced at 60 °C in 95 % ee and 98 % ee, respectively, by 1 mol % of catalyst loading. (EtO)2MeSiH proved to be the best hydrogen donor of choice. tert‐Butyl (E)‐β‐methylcinnamate and β‐isopropylcinnamate could also be reduced to the corresponding dihydrocinnamate derivatives up to 98 % ee. 相似文献
16.
β‐Bromo‐α,β‐unsaturated ketones are condensed with arylhydrazines to form hydrazones, which are in situ intramolecularly cyclized into 3‐substituted 1‐aryl‐1 H‐pyrazoles under a catalytic system of Pd(OAc)2/1,3‐bis(diphenylhosphino)propane (dppp)/NaOtBu. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
17.
Synthesis of Linear (Z)‐α,β‐Unsaturated Esters by Catalytic Cross‐Metathesis. The Influence of Acetonitrile
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Elsie C. Yu Brett M. Johnson Erik M. Townsend Prof. Richard R. Schrock Prof. Amir H. Hoveyda 《Angewandte Chemie (International ed. in English)》2016,55(42):13210-13214
Kinetically controlled catalytic cross‐metathesis reactions that generate (Z)‐α,β‐unsaturated esters selectively are disclosed. A key finding is that the presence of acetonitrile obviates the need for using excess amounts of a more valuable terminal alkene substrates. On the basis of X‐ray structure and spectroscopic investigations a rationale for the positive impact of acetonitrile is provided. Transformations leading to various E,Z‐dienoates are highly Z‐selective as well. Utility is highlighted by application to stereoselective synthesis of the C1–C12 fragment of biologically active natural product (?)‐laulimalide. 相似文献
18.
A series of new N‐aryl‐α,β‐disubstituted amides (gem or E1; trans or E2) were synthesized in good yields by carbonylative addition of aniline derivatives 1a–f to aromatic alkynes 2a,b catalyzed by Pd(OAc)2 and 1,3‐bis(diphenylphosphino)propane. The catalytic synthesis of tertiary α,β‐unsaturated amides was also successfully achieved. Traces of products were observed in the absence of p‐toluenesulfonic acid used as an additive. The reaction is sensitive to the type of phosphine ligand and solvent. Copyright © 2002 John Wiley & Sons, Ltd. 相似文献
19.
A Free‐Radical‐Promoted Stereospecific Decarboxylative Silylation of α,β‐Unsaturated Acids with Silanes
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Lizhi Zhang Zhaojia Hang Prof. Dr. Zhong‐Quan Liu 《Angewandte Chemie (International ed. in English)》2016,55(1):236-239
A stereospecific decarboxylative silylation of acrylic and propiolic acids with silanes was developed. This reaction represents the first example of decarboxylative C? Si bond formation and provides an efficient and convenient approach to various synthetically useful alkenyl and alkynyl organosilicon compounds through the reaction of α,β‐unsaturated acids with silanes. Spin‐trapping and EPR experiments support a radical addition/elimination process. 相似文献
20.
Dale C. Swenson Xiaobang Gao Donald J. Burton 《Acta Crystallographica. Section C, Structural Chemistry》2000,56(8):1040-1041
The title triene, C18H10F6, was prepared via the Pd0 coupling reaction of (E)‐(1,2‐difluoro‐1,2‐ethenediyl)bis(tributylstannane) with (Z)‐β‐iodo‐α,β‐difluorostyrene in N,N′‐dimethylformamide/tetrahydrofuran. The crystal structure shows the product to be the 1E,3E,5E isomer. Due to steric interactions between F atoms, the double bonds are not coplanar. The planes defined by the two terminal double bonds are almost perpendicular. 相似文献