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1.
Copper‐Catalyzed Domino Synthesis of 2‐Imino‐1H‐imidazol‐5(2H)‐ones and Quinoxalines Involving CC Bond Cleavage with a 1,3‐Dicarbonyl Unit as a Leaving Group
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Yan Yang Fan Ni Wen‐Ming Shu Prof. An‐Xin Wu 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(37):11776-11782
Although 2‐imino‐1H‐imidazol‐5(2H)‐ones have important biological activities in metabolism, their synthesis has rarely been investigated. Quinoxalines as “privileged scaffolds” in medicinal chemistry have been extensively investigated, but the development of novel and efficient synthetic methods remains very attractive. Herein, we have developed two copper‐catalyzed domino reactions for the synthesis of 2‐imino‐1H‐imidazol‐5(2H)‐ones and quinoxalines involving C?C bond‐cleavage with a 1,3‐dicarbonyl unit as a leaving group. The domino sequence for the synthesis of 2‐imino‐1H‐imidazol‐5(2H)‐ones includes aza‐Michael addition, intramolecular cyclization, C?C bond‐cleavage, 1,2‐rearrangement, and aerobic dehydrogenation reaction, whereas the domino sequence for the synthesis of quinoxalines includes aza‐Michael addition, intramolecular cyclization, elimination reaction, and C?C bond‐cleavage reaction. The two domino reactions have significant advantages including high efficiency, mild reaction conditions, and high tolerance of various functional groups. 相似文献
2.
A new, general palladium‐catalyzed oxidative strategy for the cleavage of the C≡C triple bond is presented. By employing PdCl2, CuBr2, TEMPO and air as the catalytic system and H2O as the carbonyl oxygen atom source, a wide range of 2‐alkynyl carbonyl compounds, including 1,3‐disubstituted prop‐2‐yn‐1‐ones, propiolamides and propiolates, lost an alkynyl carbon to access various 1,2‐dicarbonyl compounds, e.g., 1,2‐diones, 2‐keto amides and 2‐keto esters, through Wacker oxidation, intramolecular cyclization and C—C bond cleavage cascades. 相似文献
3.
Catalyst‐Dependent Chemoselective Formal Insertion of Diazo Compounds into C−C or C−H Bonds of 1,3‐Dicarbonyl Compounds
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Zhaohong Liu Dr. Paramasivam Sivaguru Prof. Giuseppe Zanoni Prof. Edward A. Anderson Prof. Xihe Bi 《Angewandte Chemie (International ed. in English)》2018,57(29):8927-8931
A catalyst‐dependent chemoselective one‐carbon insertion of diazo compounds into the C?C or C?H bonds of 1,3‐dicarbonyl species is reported. In the presence of silver(I) triflate, diazo insertion into the C(=O)?C bond of the 1,3‐dicarbonyl substrate leads to a 1,4‐dicarbonyl product containing an all‐carbon α‐quaternary center. This reaction constitutes the first example of an insertion of diazo‐derived carbenoids into acyclic C?C bonds. When instead scandium(III) triflate was applied as the catalyst, the reaction pathway switched to formal C?H insertion, affording 2‐alkylated 1,3‐dicarbonyl products. Different reaction pathways are proposed to account for this powerful catalyst‐dependent chemoselectivity. 相似文献
4.
A novel one‐pot protocol for the synthesis of valuable 3,4‐dihydropyridin‐2‐ones from the condensation of aldehyde with cyanoacetamide and 1,3‐dicarbonyl compounds in the presence of imidazole was developed. A series of aldehydes and 1,3‐dicarbonyl compounds were employed to examine the scope of substrates for this protocol. This reaction proceeded through the formation of one ring and four new bonds (two C? C, one C? N, one C?C) via the sequence involving Knoevenagel condensation, Michael addition and intramolecular cyclization with moderate to excellent yields. All new compounds were characterized by IR, 1H NMR, 13C NMR and HRMS. 相似文献
5.
《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2017,129(35):10675-10680
The silver‐catalyzed oxidative C(sp3)−H/P−H cross‐coupling of 1,3‐dicarbonyl compounds with H‐phosphonates, followed by a chemo‐ and regioselective C(sp3)−C(CO) bond‐cleavage step, provided heavily functionalized β‐ketophosphonates. This novel method based on a readily available reaction system exhibits wide scope, high functional‐group tolerance, and exclusive selectivity. 相似文献
6.
Asymmetric Desymmetrization via Metal‐Free C−F Bond Activation: Synthesis of 3,5‐Diaryl‐5‐fluoromethyloxazolidin‐2‐ones with Quaternary Carbon Centers
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Junki Tanaka Satoru Suzuki Etsuko Tokunaga Prof. Dr. Günter Haufe Prof. Dr. Norio Shibata 《Angewandte Chemie (International ed. in English)》2016,55(32):9432-9436
We disclose the first asymmetric activation of a non‐activated aliphatic C?F bond in which a conceptually new desymmetrization of 1,3‐difluorides by silicon‐induced selective C?F bond scission is a key step. The combination of a cinchona alkaloid based chiral ammonium bifluoride catalyst and N,O‐bis(trimethylsilyl)acetoamide (BSA) as the silicon reagent enabled the efficient catalytic cycle of asymmetric Csp3?F bond cleavage under mild conditions with high enantioselectivities. The ortho effect of the aryl group at the prostereogenic center is remarkable. This concept was applied for the asymmetric synthesis of promising agrochemical compounds, 3,5‐diaryl‐5‐fluoromethyloxazolidin‐2‐ones bearing a quaternary carbon center. 相似文献
7.
Martin S. Seyfried Anthony Linden Grzegorz Mlostoń Heinz Heimgartner 《Helvetica chimica acta》2009,92(9):1800-1816
The reactions of 5‐benzylidene‐3‐phenylrhodanine ( 2 ; rhodanine=2‐thioxo‐1,3‐thiazolidin‐4‐one) with diazomethane ( 7a ) and phenyldiazomethane ( 7b ) occurred chemoselectively at the exocyclic C?C bond to give the spirocyclopropane derivatives 9 and, in the case of 7a , also the C‐methylated products 8 (Scheme 1). In contrast, diphenyldiazomethane ( 7c ) reacted exclusively with the C?S group leading to the 2‐(diphenylmethylidene)‐1,3‐thiazolidine 11 via [2+3] cycloaddition and a ‘two‐fold extrusion reaction’. Treatment of 8 or 9b with an excess of 7a in refluxing CH2Cl2 and in THF at room temperature in the presence of [Rh2(OAc)4], respectively, led to the 1,3‐thiazolidine‐2,4‐diones 15 and 20 , respectively, i.e., the products of the hydrolysis of the intermediate thiocarbonyl ylide. On the other hand, the reactions with 7b and 7c in boiling toluene yielded the corresponding 2‐methylidene derivatives 16, 21a , and 21b . Finally, the reaction of 11 with 7a occurred exclusively at the electron‐poor C?C bond, which is conjugated with the C?O group. In addition to the spirocyclopropane 23 , the C‐methylated 22 was formed as a minor product. The structures of the products (Z)‐ 8, 9a, 9b, 11 , and 23 were established by X‐ray crystallography. 相似文献
8.
Evgeny V. Shchegol'kov Anna E. Ivanova Yanina V. Burgart Viktor I. Saloutin 《Journal of heterocyclic chemistry》2013,50(Z1):E80-E86
Azo coupling of 1,3‐dicarbonyl compounds with tetrazolyl‐5‐diazonium chloride is used to develop a convenient one‐step procedure for the synthesis of 4,7‐dihydrotetrazolo[5,1‐c][1,2,4]triazines. In contrast to nonfluorinated analogs, 7‐hydroxy‐7‐polyfluoroalkyl‐4,7‐dihydrotetrazolo[5,1‐c][1,2,4]triazines undergo a ring‐chain isomerism resulting from the cleavage at the C7―N7a bond. A distinctive feature of nonfluorinated 4,7‐dihydrotetrazolo[5,1‐c][1,2,4]triazines is the possibility to dehydration, which is accompanied by an azide rearrangement due to the tetrazole ring cleavage with the formation of tetrazolo[1,5‐b][1,2,4]triazines. 相似文献
9.
4‐Ethoxycarbonyl‐5‐phenyl‐2,3‐dihydrofuran‐2,3‐dione 1 reacts with aldehydes via the acylketene intermediate 2 giving the 1,3‐dioxin‐4‐ones 3a‐e and the 1,4‐bis(5‐ethoxycarbonyl‐4‐oxo‐6‐phenyl‐4H‐1,3‐dioxin‐2‐yl)benzene 4 , and a one step reaction between dibenzoylmethane and oxalylchloride gave 3,5‐dibenzoyl‐2,6‐diphenyl‐4‐pyrone 7 . The reaction of 1 with dibenzoylmethane, a dicarbonyl compound, provided ethyl 3‐benzoyl‐4‐oxo‐2,6‐diphenylpyran‐5‐carboxylate derivative 9 . Compound 9 was converted into the corresponding ethyl 3‐benzoyl‐4‐hydroxy‐2,6‐diphenylpyridine‐5‐carboxylate derivative 10 via its reaction with ammonium hydroxyde solution in 1 ‐butanol. 相似文献
10.
11.
Highly Selective Copper‐Catalyzed Asymmetric [3+2] Cycloaddition of Azomethine Ylides with Acyclic 1,3‐Dienes
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María González‐Esguevillas Ana Pascual‐Escudero Dr. Javier Adrio Prof. Dr. Juan C. Carretero 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(12):4561-4565
The first examples of the catalytic asymmetric 1,3‐dipolar cycloaddition of azomethine ylides with acyclic activated 1,3‐dienes (and 1,3‐enynes) are described. Under copper catalysis, a selective cycloaddition at the terminal γ,δ‐C?C bond is observed. In addition, depending on the ligand used, either the exo or the endo adduct can be obtained with high selectivity. Under appropriate reaction conditions, the acyclic 1,6‐addition product is detected, suggesting a stepwise mechanism. The resulting C4‐alkenyl‐substituted pyrrolidines are suitable substrates for further access to polycyclic systems, as highlighted by the preparation of hexahydrochromeno[4,3‐b]pyrrole and the tetracyclic core of the alkaloid gracilamine. 相似文献
12.
Cycloadditions of 2‐cyclopropylidene‐1,3‐dimethylimidazolidine ( 1 ), a strong, electron‐rich C‐nucleophile, with a variety of aryl‐substituted 1,2,4‐triazines occur at temperatures between ?100 and +100°, depending on the substitution pattern. At low temperatures, zwitterions, formed by nucleophilic attack of 1 on the triazines, could be detected spectroscopically and, in some cases, isolated. Two types of zwitterions were found: 1) those where the new bond was linked to C(5) of the triazine and which were formed in a reversible dead‐end equilibrium, and 2) those where the new bond was linked either to C(3) or C(6). The latter exhibited the same regiochemistry as the final cycloadducts, and might be intermediates of a two‐step Diels–Alder reaction. Energies and structural characteristics for stationary points in the reaction of monosubstituted triazines with 1 in the gas phase and in CH2Cl2 solution were calculated at the Becke3LYP/6‐311+G(d,p)//Becke3LYP/6‐31G(d) level of theory. Different reaction mechanisms are discussed on the basis of steric, electronic, and solvent effects. 相似文献
13.
3(2H)‐Furanones are efficiently generated from 3‐alkynyl oxireno[2,3‐b]chromenones by an Au/DDQ‐catalyzed domino reaction through a pathway composed of cyclization, C? C cleavage, nucleophilic addition, oxidation, and nucleophilic addition. It was found that stoichiometric AuCl3 or catalytic Au with stoichiometric DDQ can oxidize the benzylic sp3 C? H bond to facilitate nucleophilic addition. 相似文献
14.
Hiroaki Oie Atsushi Sudo Takeshi Endo 《Journal of polymer science. Part A, Polymer chemistry》2010,48(23):5357-5363
Thermally induced ring‐opening polymerization of monofunctional N‐allyl‐1,3‐benzoxazine 1a was compared with that of N‐(n‐propyl)‐1,3‐benzoxazine 1b to clarify an unexpected effect of allyl group to promote the polymerization, that is, in spite of the comparable bulkiness of allyl group to n‐propyl group, the polymerization of 1a was much faster than that of 1b . Such a difference in polymerization rate was also observed similarly in the comparison of thermally induced polymerization of a bifunctional N‐allyl‐benzoxazine 2a with that of a bifunctional N‐(n‐propyl) analogue 2b . These observations implied a certain contribution of an electron‐rich C? C double bond of the N‐ally group to promotion of the ring‐opening reaction of 1,3‐benzoxazine into the corresponding zwitterionic species, which would involve a mechanism to stabilize the cationic part of the zwitterionic species based on “neighboring group participation” of the C? C double bond. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2010 相似文献
15.
The 2‐thienyl‐substituted 4,5‐dihydrofuran derivatives 3 – 8 were obtained by the radical cyclization reaction of 1,3‐dicarbonyl compounds 1a – 1f with 2‐thienyl‐substituted conjugated alkenes 2a – 2e by using [Mn(OAc)3] (Tables 1–5). In this study, reactions of 1,3‐dicarbonyl compounds 1a – 1e with alkenes 2a – 2c gave 4,5‐dihydrofuran derivatives 3 – 5 in high yields (Tables 1–3). Also the cyclic alkenes 2d and 2e gave the dihydrobenzofuran compounds, i.e., 6 and 7 in good yields (Table 4). Interestingly, the reaction of benzoylacetone (=1‐phenylbutane‐1,3‐dione; 1f ) with some alkenes gave two products due to generation of two stable carbocation intermediates (Table 5). 相似文献
16.
An efficient proline‐catalyzed synthesis of 4,5‐disubstituted‐N‐sulfonyl‐1,2,3‐triazoles has been accomplished from 1,3‐dicarbonyl compounds and sulfonyl azides. The developed reaction is suitable for various symmetrical and unsymmetrical 1,3‐dicarbonyl compounds, tolerates various functional groups and affords 4,5‐disubstituted‐N‐sulfonyl‐1,2,3‐triazoles in good yield with excellent regioselectivity. Rhodium‐catalyzed denitrogenative functionalization of 4,5‐disubstituted‐N‐sulfonyl‐1,2,3‐triazoles further demonstrates their utility in organic synthesis. 相似文献
17.
A series of novel 4‐(2‐(4‐bromophenyl)‐1,2,3‐triazol‐4‐yl)‐3,4‐dihydropyrimidin‐2(1H)‐ones/thiones were prepared by condensing 2‐(4‐bromophenyl)‐4‐formyl‐1,2,3‐triazole with 1,3‐dicarbonyl compound and urea or thiourea using Mg(NO3)2 as an efficient and cheap catalyst. The satisfactory results were obtained with excellent yields and short reaction time. J. Heterocyclic Chem., (2010). 相似文献
18.
α,β‐Double Electrophilic Addition of Allene‐1,3‐Dicarboxylic Esters for the Construction of Polysubstituted Furans by KI/tert‐Butyl Hydroperoxide (TBHP)‐Promoted Oxidative Annulation
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Hong‐Liang Li Yu Wang Pei‐Pei Sun Prof. Dr. Xiaoyan Luo Prof. Dr. Zhenlu Shen Prof. Dr. Wei‐Ping Deng 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(27):9348-9355
An unprecedented KI/tert‐butyl hydroperoxide promoted tandem Michael addition/oxidative annulation of allene‐1,3‐dicarboxylic esters and 1,3‐dicarbonyl compounds has been developed. This procedure provides a new, facile, and transition‐metal‐free synthetic approach to afford polysubstituted furans in moderate to excellent yields (up to 93 %). This method first establishes a α,β‐double electrophilic reaction mode of allene‐1,3‐dicarboxylic esters to form 1,3‐dicarbonyl compounds. 相似文献
19.
Stereoselective Synthesis of 1,3‐Diaminotruxillic Acid Derivatives: An Advantageous Combination of CH‐ortho‐Palladation and On‐Flow [2+2]‐Photocycloaddition in Microreactors
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Dr. Elena Serrano Dr. Alberto Juan Angel García‐Montero Dr. Tatiana Soler Francisco Jiménez‐Márquez Prof. Dr. Carlos Cativiela Dr. M. Victoria Gomez Dr. Esteban P. Urriolabeitia 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(1):144-152
The stereoselective synthesis of ε‐isomers of dimethyl esters of 1,3‐diaminotruxillic acid in three steps is reported. The first step is the ortho‐palladation of (Z)‐2‐aryl‐4‐aryliden‐5(4H)‐oxazolones 1 to give dinuclear complexes 2 with bridging carboxylates. The reaction occurs through regioselective activation of the ortho‐C?H bond of the 4‐arylidene ring in carboxylic acids. The second step is the [2+2]‐photocycloaddition of the C?C exocyclic bonds of the oxazolone skeleton in 2 to afford the corresponding dinuclear ortho‐palladated cyclobutanes 3 . This key step was performed very efficiently by using LED light sources with different wavelengths (465, 525 or 625 nm) in flow microreactors. The final step involved the depalladation of 3 by hydrogenation in methanol to afford the ε‐1,3‐diaminotruxillic acid derivatives as single isomers. 相似文献
20.
Ruthenium(II)‐Catalyzed C−H Activation of Imidamides and Divergent Couplings with Diazo Compounds: Substrate‐Controlled Synthesis of Indoles and 3H‐Indoles
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Yunyun Li Dr. Zisong Qi Dr. He Wang Xifa Yang Prof. Xingwei Li 《Angewandte Chemie (International ed. in English)》2016,55(39):11877-11881
Indoles are an important structural motif that is commonly found in biologically active molecules. In this work, conditions for divergent couplings between imidamides and acceptor–acceptor diazo compounds were developed that afforded NH indoles and 3H‐indoles under ruthenium catalysis. The coupling of α‐diazoketoesters afforded NH indoles by cleavage of the C(N2)?C(acyl) bond whereas α‐diazomalonates gave 3H‐indoles by C?N bond cleavage. This reaction constitutes the first intermolecular coupling of diazo substrates with arenes by ruthenium‐catalyzed C?H activation. 相似文献