- Thiocarbamate-directed Cp*Co(III)-Catalyzed Olefinic C?H Amidation: Facile Access to Enamines with High (Z)-Selectivity
-
A thiocarbamate-directed Cp*Co(III)-catalyzed C?H oxidative amidation of olefins is achieved to synthesize a series of enamines. The key feature of this protocol is the use of earth-abundant cobalt as catalyst and thiocarbamate as directing group, which provides an efficient and simple manner to synthesize enamines in good yields with high (Z)-selectivity. This reaction proceeds smoothly under very mild conditions (rt and air), and a wide range of functionalized alkenes, as well as dioxazolones, were compatible with the standard reaction conditions.
- Liang, Ya-Ru,Si, Xiao-Ju,Zhang, He,Yang, Dandan,Niu, Jun-Long,Song, Mao-Ping
-
-
Read Online
- Bimetallic Cooperative Catalysis for Decarbonylative Heteroarylation of Carboxylic Acids via C-O/C-H Coupling
-
Cooperative bimetallic catalysis is a fundamental approach in modern synthetic chemistry. We report bimetallic cooperative catalysis for the direct decarbonylative heteroarylation of ubiquitous carboxylic acids via acyl C-O/C-H coupling. This novel catalytic system exploits the cooperative action of a copper catalyst and a palladium catalyst in decarbonylation, which enables highly chemoselective synthesis of important heterobiaryl motifs through the coupling of carboxylic acids with heteroarenes in the absence of prefunctionalization or directing groups. This cooperative decarbonylative method uses common carboxylic acids and shows a remarkably broad substrate scope (>70 examples), including late-stage modification of pharmaceuticals and streamlined synthesis of bioactive agents. Extensive mechanistic and computational studies were conducted to gain insight into the mechanism of the reaction. The key step involves intersection of the two catalytic cycles via transmetallation of the copper–aryl species with the palladium(II) intermediate generated by oxidative addition/decarbonylation.
- Liu, Chengwei,Ji, Chong-Lei,Zhou, Tongliang,Hong, Xin,Szostak, Michal
-
supporting information
p. 10690 - 10699
(2021/04/09)
-
- Pd/Cu-Catalyzed C-H/C-H Cross Coupling of (Hetero)Arenes with Azoles through Arylsulfonium Intermediates
-
A highly efficient method for the selective formal C-H/C-H cross-coupling of azoles and (hetero)arenes was established through arylsulfonium intermediates under transition-metal catalysis, which produced a variety of 2-(hetero)aryl azoles in good to excellent yields. Advantages of the reaction included mildness, a good functional group tolerance, a wide range of substrates, a high regio- and chemoselectivity, one-pot procedures, and the late-stage functionalization of complex molecules without the use of oxidants, offering a promising strategy for the transition-metal-catalyzed C-H arylation of azoles.
- Lin, Zeng-Hui,Tian, Ze-Yu,Zhang, Cheng-Pan
-
supporting information
p. 4400 - 4405
(2021/06/27)
-
- Synthesis of α-Amidoketones through the Cascade Reaction of Carboxylic Acids with Vinyl Azides under Catalyst-Free Conditions
-
An efficient synthesis of α-amidoketone derivatives through the cascade reactions of carboxylic acids with vinyl azides is presented. Compared with literature protocols, notable features of this new method include catalyst-free conditions, broad substrate scope, good tolerance of a wide range of functional groups, and high efficiency. In addition, the synthetic potential of this method as a tool for late-stage modification was convincingly manifested by its application in the structural elaborations of a number of carboxylic acid drug molecules.
- Gao, Cai,Zhou, Qianting,Yang, Li,Zhang, Xinying,Fan, Xuesen
-
p. 13710 - 13720
(2020/11/13)
-
- Synthesis method of alpha-acylamino ketone compound
-
The invention discloses a synthesis method of an alpha-acylamino ketone compound, and belongs to the technical field of organic synthesis. The preparation method comprises the following steps: mixingan alkenyl azide compound 1, a carboxylic acid compound 2 and an organic solvent, and heating to react to obtain the alpha-acylamino ketone compound 3. Compared with the prior art, the method has thefollowing advantages: (1) the synthesis process is simple and efficient, no catalyst is needed in the whole process, and the alpha-acylamino ketone compound can be obtained with high yield by dissolving the alkenyl azide compound and the carboxylic acid compound in the solvent and stirring; (2) raw materials are cheap and easy to obtain, reaction conditions are mild, and operation is simple; (3) the substrate is wide in application range and can be used for modifying drug molecules; and (4) the atom economy is high, and the requirements of green chemistry are met.
- -
-
Paragraph 0151-0154
(2020/12/08)
-
- Photoinduced Heterogeneous C?H Arylation by a Reusable Hybrid Copper Catalyst
-
Heterogeneous copper catalysis enabled photoinduced C?H arylations under exceedingly mild conditions at room temperature. The versatile hybrid copper catalyst provided step-economical access to arylated heteroarenes, terpenes and alkaloid natural products with various aryl halides. The hybrid copper catalyst could be reused without significant loss of catalytic efficacy. Detailed studies in terms of TEM, HRTEM and XPS analysis of the hybrid copper catalyst, among others, supported its outstanding stability and reusability.
- Choi, Isaac,Müller, Valentin,Lole, Gaurav,K?hler, Robert,Karius, Volker,Vi?l, Wolfgang,Jooss, Christian,Ackermann, Lutz
-
supporting information
p. 3509 - 3514
(2020/03/03)
-
- Synthesis method of oxazole heterocyclic compound
-
The invention belongs to the technical field of organic synthesis and medicines, and particularly relates to a synthesis method of an oxazole heterocyclic compound. Aryl aldehyde and a triazole derivative are used as raw materials and are heated to react in the presence of trichloromethane and rhodium acetate catalysts to obtain the oxazole heterocyclic compound. By using the method provided by the invention, under the condition of heating and stirring, the oxazole heterocyclic derivative can be obtained at a relatively high yield after reaction for 3-12 hours. According to the method disclosed by the invention, the oxazole heterocyclic derivative is simply, conveniently and efficiently synthesized by using simple and easily available raw materials through a one-step method, and a simple and efficient new synthesis method with wide substrate universality is provided for synthesizing the oxazole heterocyclic derivative.
- -
-
-
- Synthesis of 2,5-diaryloxazoles through rhodium-catalyzed annulation of triazoles and aldehydes
-
An efficient synthesis of a variety of 2,5-diaryloxazole derivatives via a rhodium-catalyzed annulation of triazoles and aldehydes is achieved. Various oxazole derivatives could be obtained in good to excellent yields. A concise synthesis of antimycobaterial natural products balsoxin and texamine has been achieved using this method. This journal is
- Li, Jian,Liu, Li,Lu, Xue-Chen,Wang, Zheng-Bing,Xu, De-Feng,Xu, Yue,Zhu, Shang-Rong
-
p. 24795 - 24799
(2020/07/14)
-
- Reaction Conditions for the Regiodivergent Direct Arylations at C2- or C5-Positions of Oxazoles using Phosphine-Free Palladium Catalysts
-
Two sets of reaction conditions for the regiodivergent C2- or C5- direct arylations of oxazole are reported. In both cases, phosphine-free catalysts and inexpensive bases were employed allowing the access to the arylated oxazoles in moderate to high yields. Using Pd(OAc)2/KOAc as catalyst and base, regioselective C5-arylations were observed; whereas, using Pd(acac)2/Cs2CO3 system, the arylation occurred at the C2-position of oxazole. The higher reactivity of C5-H bond of oxazole as compared to the C2-H bond in the presence of Pd(OAc)2/KOAc system is consistent with a concerted metalation deprotonation mechanism; whereas the C2-arylation likely occurs via a simple base deprotonation of the oxazole C2-position. Then, from these C2- or C5-arylated oxazoles, a second palladium-catalyzed direct C?H bond arylation affords 2,5-diaryloxazoles with two different aryl groups. We also applied these sequential arylations to the straightforward synthesis of 2-arylphenanthro[9,10-d]oxazoles via three C?H bond functionalization steps. The Ru-catalyzed C?H arylation of the aryl unit of 2-aryloxazoles is also described. (Figure presented.).
- Shi, Xinzhe,Soulé, Jean-Fran?ois,Doucet, Henri
-
p. 4748 - 4760
(2019/09/12)
-
- Divergent Conversion of N-Acyl-isoxazol-5(2 H)-ones to Oxazoles and 1,3-Oxazin-6-ones Using Photoredox Catalysis
-
The fragmentation of N-acyl-isoxazol-5-ones using visible light photoredox catalysis has been disclosed. The catalyst-controlled divergent mechanisms, namely the oxidative and reductive quenching catalytic cycle, are utilized. Various oxazoles and 1,3-oxazin-6-ones are selectively obtained from the same isoxazol-5-one skeleton under mild conditions.
- Mei, Mingjing,Anand, Devireddy,Zhou, Lei
-
p. 3548 - 3553
(2019/05/24)
-
- Catalytic C?H/C?F Coupling of Azoles and Acyl Fluorides
-
A method for the palladium/copper-catalyzed direct acylation of azoles with acyl fluorides is described. This study reports the first examples of acyl fluorides being used as acylation reagents in transition-metal-catalyzed aromatic C?H bond functionalization reactions. Depending on the reaction temperature, decarbonylative coupling may also occur. Mechanistic studies suggest that the cleavage of the aromatic C?H bond, promoted by a copper-phosphine species, is not the rate-limiting step of this acylation.
- Ogiwara, Yohei,Iino, Yurika,Sakai, Norio
-
supporting information
p. 6513 - 6516
(2019/04/27)
-
- CO2/Photoredox-Cocatalyzed Tandem Oxidative Cyclization of α-Bromo Ketones and Amines to Construct Substituted Oxazoles
-
CO2/photoredox-cocatalyzed tandem oxidative cyclization of α-bromo ketones and amines for the preparation of substituted oxazoles has been achieved. The avoidance of using both transition-metal catalysts and peroxides makes this method more sustainable and renewable.
- Zhang, Xiaowei,He, Yonghui,Li, Jing,Wang, Rui,Gu, Lijun,Li, Ganpeng
-
p. 8225 - 8231
(2019/06/17)
-
- Silver-Induced [3+2] Cycloaddition of Isocyanides with Acyl Chlorides: Regioselective Synthesis of 2,5-Disubstituted Oxazoles
-
A silver-induced cycloaddition of isocyanides with acyl chlorides has been developed. This transition metal-catalyzed strategy provides an effective and scalable approach for the formation of 2,5-disubstituted oxazoles in good to high yields. The employed silver-based MOF catalyst can be efficiently recycled without compromising the yield.
- Liu, Jian-Quan,Shen, Xuanyu,Shatskiy, Andrey,Zhou, Enlong,K?rk?s, Markus D.,Wang, Xiang-Shan
-
p. 4272 - 4275
(2019/07/19)
-
- A 2, 5 - diaryl five-membered heterocyclic aromatic preparation method
-
The invention relates to a 2, 5 - diaryl five-membered heterocyclic aromatic preparation method, the method is to turn the diaryl Iodized salt compounds, five-membered heterocyclic aromatic compound, catalyst, ligand, alkali and solvent are mixed uniformly, in 100 °C -140 °C lower sealing reaction for 24 hours, the reaction solution obtained after the reaction is complete; the reaction solution are often gauge extraction, drying, concentration, column chromatography separation to obtain the 2, 5 - diaryl five-membered heterocyclic aromatic compounds. The invention belongs to a pot of reaction of the atom economy, simple operation, high yield, can realize the large-scale production, in functional organic material, biological active compounds and pharmaceutical synthesis of better industrial application prospect.
- -
-
Paragraph 0024; 0025; 0026; 0027; 0028; 0029
(2019/05/15)
-
- Synthesis of 2,5-Disubstituted Oxazoles from Arylacetylenes and α-Amino Acids through an i 2 /Cu(NO 3) 2 ?3H 2 O-Assisted Domino Sequence
-
A new strategy has been developed for the synthesis of 2,5-disubstituted oxazoles from easily available arylacetylenes and α-amino acids in the presence of Cu(NO 3) 2 ?3H 2 O and iodine. This reaction process involves the I 2 /Cu(NO 3) 2 ?3H 2 O-assisted transformation of arylacetylene to α-iodo acetophenone, Kornblum oxidation to phenylglyoxal, condensation to imine, decarboxylation/annulation/oxidation reaction sequence to approach 2,5-disubstituted oxazoles.
- Wang, Jungang,Cheng, Yan,Xiang, Jiachen,Wu, Anxin
-
supporting information
p. 743 - 747
(2019/03/26)
-
- Photoactivated N-Acyliminoiodinanes Applied to Amination: an ortho-Methoxymethyl Group Stabilizes Reactive Precursors
-
N-Acyliminoiodinanes were characterized for the first time by X-ray structural analysis. The ortho-methoxymethyl group and the carbonyl oxygen coordinate to the iodine atom of the iminoiodinane. Activation of the N-acyliminoiodinane was achieved by photoirradiation at 370 nm, thereby enabling reaction with various silyl enol ethers to give α-aminoketone derivatives in good to high yield. N-sulfonyliminoiodinanes bearing ortho substituents were used in photoinduced amination.
- Kobayashi, Yusuke,Masakado, Sota,Takemoto, Yoshiji
-
supporting information
p. 693 - 697
(2018/01/17)
-
- Displacement of η5-cyclopentadienyl ligands from half-sandwich: C, C -(NHC-cyanoalkyl)-nickel(II) metallacycles: Further insight into the structure of the resulting Cp-free nickelacycles and a catalytic activity study
-
Four cationic C,C-(NHC-cyanoalkyl)-nickel(ii) metallacyclic complexes, [Ni{Me-NHC-CH2CH(CN)}(NCMe)](PF6) (2a), [Ni{Mes-NHC-CH2CH(CN)}(NCMe)](PF6) (2b), [Ni{Mes-NHC-(CH2)2CH(CN)}(NCMe)](PF6) (2c) and [Ni{DiPP-NHC-(CH2)2CH(CN)}(NCMe)](PF6) (2d), were prepared by the removal of the Cp ligand under acidic conditions at 0 °C from the corresponding half-sandwich nickelacycles [NiCp{R-NHC-(CH2)nCH(CN)}] (1a-1d; Cp = η5-C5H5; n = 1 or 2; R-NHC-(CH2)nCH(CN) = 1-R-3-[(CH2)nCH(CN)]-imidazol-2-ylidene). Full characterization of 2a-d by 1H and 13C{1H} NMR spectroscopy in CD3CN and pyridine-d5, ATR-FTIR spectroscopy, mass spectrometry, and CHN microanalyses established the presence of only one acetonitrile ligand per nickel atom in the solid state. A DFT structural study conducted on the cations of the methyl-substituted 5-membered nickelacycle 2a and the mesityl-substituted 6-membered cycle 2c found a small energetic cost (ΔG = 7-12 kcal mol-1) for the loss of one acetonitrile ligand from the square-planar structures existing in solution, that should be easily amenable upon solvent evaporation (ΔG? = 14 kcal mol-1 in the case of 2c). Two structures with one acetonitrile ligand could be optimized in both cases: (i) a truly T-shaped 14-electron structure with an end-on acetonitrile ligand, and (ii) a masked T-shaped structure stabilized by the π-coordination of the dangling CN group of the metallated alkyl chain, the latter being favoured by 2.4 kcal mol-1 in the case of the flexible 6-membered ring 2c. A comparison of calculated vibrational frequencies with experimental FTIR spectra ruled out π-coordination of the dangling CN group as a ν(CN) band at low frequency was absent. Complexes 2a-d thus probably exist as rare three-coordinate T-shaped 14-electron species in the solid state. Their catalytic activity was studied for the direct arylation of azoles, and 2c proved to be moderately active for the coupling of benzothiazole with aryl iodides. Mechanistic insights suggest that competing processes or a radical process catalysed by nickel particles could follow an initial reduction of 2c by the dimerization of a sacrificial amount of benzothiazole.
- Cardoso, Bernardo De P.,Bernard-Schaaf, Jean-Marie,Shahane, Saurabh,Veiros, Luis F.,Chetcuti, Michael J.,Ritleng, Vincent
-
p. 1535 - 1547
(2018/02/09)
-
- Metal-free iodine(iii)-promoted synthesis of 2,5-diaryloxazoles
-
A nonmetal-catalyzed oxidative cyclization to achieve 2,5-disubstituted oxazoles from inexpensive and readily available substituted chalcone, (diacetoxyiodo)benzene (PIDA) and ammonium acetate (NH4OAc) at room temperature is described. The reaction forms a variety of 2,5-diaryloxazoles in good to excellent yields with broad substrate scope under mild conditions without the requirement of ligands and additional bases.
- Yang, Xueying,Guo, Xin,Qin, Mingda,Yuan, Xinglong,Jing, Huanwang,Chen, Baohua
-
supporting information
p. 3104 - 3108
(2018/05/22)
-
- Synthesis of 2,5-disubstituted oxazoles: Via cobalt(III)-catalyzed cross-coupling of N -pivaloyloxyamides and alkynes
-
An efficient synthesis of 2,5-disubstituted oxazoles via Co(iii) catalysis is described herein. The synthesis is achieved under mild conditions through [3+2] cycloaddition of N-pivaloyloxyamides and alkynes. The reaction operates through an internal oxidation pathway and features a very broad substrate scope. The one-step synthesis of natural products such as texamine and balsoxin has been demonstrated via this protocol.
- Yu, Xiaolong,Chen, Kehao,Wang, Qi,Zhang, Wenjing,Zhu, Jin
-
supporting information
p. 1197 - 1200
(2018/02/09)
-
- Nickel-catalyzed C?H arylation of benzoxazoles and oxazoles: Benchmarking the influence of electronic, steric and leaving group variations in phenolic electrophiles
-
Electronic, steric and leaving group effects for Ni-catalyzed direct arylations using C?O electrophiles were benchmarked. The scope of arylations with pivalates was general with respect to both the electronics on the electrophile and the azoles. Furthermore, the arylation of azoles with tosylates, mesylates and carbamates with varying electronics was explored, and showed electronic trends similar to those of the pivalate reactions. Finally, the relative rate of arylation of 5-methyl benzoxazole with two electronically-similar electrophiles bearing different leaving groups was established. The results from these studies implicate the following order of relative reactivity: mesylates>pivalates>carbamates.
- Steinberg, Deborah F.,Turk, Morgan C.,Kalyani, Dipannita
-
supporting information
p. 2196 - 2209
(2017/03/24)
-
- A cuprous catalytic phenmethyl nitrine with styrene synthesis of 2, 5 - disubstituted-oxazole
-
The invention discloses a preparation method for synthesizing 2,5-disubstituted oxazoles from benzyl azide and styrene under the catalysis of sub copper. The method comprises the following steps of (1) preparing a substituent azide; (2) reacting azide with styrene to prepare a product. According to the method, the raw materials are simple, reaction conditions are moderate, and the method has high application value, and is suitable for industrial production.
- -
-
Paragraph 0026; 0027; 0028; 0029; 0030; 0031
(2017/08/25)
-
- A Heterogeneous Gold(I)-Catalyzed [2 + 2 + 1] Annulation of Terminal Alkynes, Nitriles, and Oxygen Atoms Leading to 2,5-Disubstituted Oxazoles
-
The first heterogeneous gold(I)-catalyzed [2 + 2 + 1] annulation of terminal alkynes, nitriles, and oxygen atoms has been achieved by using an MCM-41-immobilized phosphine-gold(I) complex as catalyst and 8-methylquinoline N-oxide as oxidant under mild conditions, yielding a variety of 2,5-disubstituted oxazoles in good to excellent yields with broad substrate scope. The new heterogeneous gold(I) catalyst can easily be recovered by simple filtration of the reaction solution and recycled for at least eight times without significant loss of activity.
- Yang, Weisen,Zhang, Rongli,Yi, Feiyan,Cai, Mingzhong
-
p. 5204 - 5211
(2017/05/24)
-
- 2,5-diphenyl-oxazole preparation method
-
The invention relates to a method for preparing scintillation pure grade 2,5-diphenyl oxazole (DPO or PPO for short). The method comprises the following steps: by taking benzoyl glycine as a raw material, performing multiple steps of reaction such as acylating chlorination, Frieldel-Crafts and ring formation, purifying middle products of each step without being separated, and preparing 2,5-diphenyl oxazole by using a one-pot method. An obtained product can be rectified and purified, the requirements of a scintillator cannot be met but metal oxide heating treatment is needed, and thus a 2,5-diphenyl oxazole product for scintillation fluor can be obtained. As the one-pot method is adopted to prepare 2,5-diphenyl oxazole, the reaction steps are reduced, the operation process is simplified, the production efficiency is improved, a purification method is simple, convenient and effective, and on-scale industrialization production is achieved.
- -
-
Paragraph 0026-0031; 0036; 0039
(2019/02/04)
-
- Substituted azole penta-heterocyclic derivatives and solvothermal one-pot synthesis method and application thereof
-
The invention belongs to the technical field of organic synthesis and particularly discloses a series of substituted azole penta-heterocyclic derivatives and a solvothermal one-pot synthesis method thereof. By the adoption of the solvothermal one-pot synthesis method for preparing the target product, reaction time is short, a solvent is not prone to volatilization in an airtight system, recycling can be realized, production cost is effectively reduced, the advantages of energy conservation and environment friendliness are achieved, operation is easy, yield is high, and the prepared substituted azole penta-heterocyclic derivatives have good anti-microbial biological activity and excellent photophysical properties such as electron conductivity, the fluorescence property and the ultraviolet property, thereby having very high development and application value.
- -
-
Paragraph 0062; 0063; 0064
(2016/11/02)
-
- Synthesis of Substituted Oxazoles by Visible-Light Photocatalysis
-
A simple and practical method for the synthesis of substituted oxazoles has been developed using readily available α-bromoketones and benzylamines by visible-light photocatalysis at room temperature. The process, which requires 1 mol % of [Ru(bpy)3]Cl2 photocatalyst with K3PO4 and CCl3Br, is effective for accessing a variety of valuable oxazole compounds. The synthetic utility of our protocol was also demonstrated by preparing a natural product, texaline.
- Chatterjee, Tanmay,Cho, Ji Young,Cho, Eun Jin
-
p. 6995 - 7000
(2016/08/30)
-
- Photoinduced Copper-Catalyzed C-H Arylation at Room Temperature
-
Room-temperature azole C-H arylations were accomplished with inexpensive copper(I) compounds by means of photoinduced catalysis. The expedient copper catalysis set the stage for site-selective C-H arylations of non-aromatic oxazolines under mild reaction conditions, and provides step-economical access to the alkaloid natural products balsoxin and texamine. Copper light: Room-temperature C-H arylations of heteroarenes were accomplished with inexpensive copper compounds by photoinduced catalysis. The expedient copper catalysis leads to site-selective C-H arylations of non-aromatic oxazolines under mild reaction conditions, and provides step-economical access to the alkaloid natural products balsoxin and texamine.
- Yang, Fanzhi,Koeller, Julian,Ackermann, Lutz
-
supporting information
p. 4759 - 4762
(2016/04/19)
-
- An efficient two-step synthesis of 2,5-disubstituted oxazole derivatives involving cu-promoted carbon-carbon single bond formation
-
Environment sensitive fluorescence probe to detect various organelles is emerging as an excellent tool to attract the attention of a large number of researchers around the globe. The recent developments have shown that oxazole dyes are very competent and can exhibit a useful fluorescence property in this direction. An efficient synthetic procedure towards 2,5-diaryl substituted oxazole derivatives have been reported. It is a two-step technique involving classical van Leusen protocol followed by copper-mediated coupling with aryl halides to introduce the required carbon-carbon single bond. The aryl groups are chosen in such a way so that the aryl functionalities at 2- and 5-positions of oxazole can act as acceptor and donor moiety respectively. Thus, in turn, the extended conjugation from donor moiety to acceptor moiety via the oxazole ring is set up therein. The oxazole derivatives were characterized by various spectroscopic measurements like NMR, IR and MS.
- Maiti, Jyotirmay,Biswas, Suman,Das, Ranjan
-
p. 1519 - 1522
(2016/05/09)
-
- One-pot preparation of 2,5-disubstituted and 2,4,5-trisubstituted oxazoles from aromatic ketones with molecular iodine, oxone, and trifluoromethanesulfonic acid in nitriles
-
Alkyl aryl ketones were successfully converted into the corresponding 2,5-disubstituted and 2,4,5-trisubstituted oxazoles in good to moderate yields in a one-pot manner, utilizing iodine, Oxone, and trifluoromethanesulfonic acid in nitriles under transition-metal-free conditions. The present method could be used for the preparation of Oxaprozin from benzyl phenyl ketone and succinonitrile. A possible reaction mechanism was proposed in which the key intermediates were α-iodoalkyl aryl ketones and α-iodosylalkyl aryl ketones.
- Imai, Sho,Kikui, Hiroki,Moriyama, Katsuhiko,Togo, Hideo
-
p. 5267 - 5274
(2015/07/15)
-
- A convenient strategy to 2,4,5-triaryl and 2-alkyl-4,5-diaryl oxazole derivatives through silver-mediated oxidative CO cross coupling/cyclization
-
This is a silver(I) mediated Cα(sp3)H activation of primary amines followed by oxidative CO cross coupling/cyclization for the construction of 2,4,5-triaryl and 2-alkyl-4,5-diaryl oxazole derivatives. The protocol has been successfully utilized to synthesize the oxazole derivatives in good to excellent yields. In this oxidative coupling, the silver species after the reaction was successfully re-synthesized and reused with almost a similar activity.
- Sarkar, Rajib,Mukhopadhyay, Chhanda
-
supporting information
p. 3872 - 3876
(2015/06/08)
-
- A facile synthesis of 2,5-disubstituted oxazoles via a copper-catalyzed cascade reaction of alkenes with azides
-
A novel and efficient approach to the synthesis of 2,5-disubstituted oxazoles is developed via a 1,3-dipolar cycloaddition/ring cleavage/1,2-H migration/denitrogenation/copper-catalyzed aerobic oxidative dehydrogenative cyclization cascade. The desired products can be obtained from readily available aromatic terminal alkenes and azides employing air as the oxidant under mild conditions, and it offers an attractive alternative method for the synthesis of oxazole derivatives.
- Li, Jiu-Ling,Wang, Ying-Chun,Li, Wei-Ze,Wang, Heng-Shan,Mo, Dong-Liang,Pan, Ying-Ming
-
p. 17772 - 17774
(2015/12/18)
-
- Metal-Free sp3 C-H Functionalization: PABS/I2-Promoted Synthesis of Polysubstituted Oxazole Derivatives from Arylethanones and 2-Amino-2-alkyl/arylacetic Acid
-
A nonmetal-catalyzed process for the synthesis of polysubstituted oxazoles from inexpensive and readily available α-amino acids and methyl ketones is established. This reaction is proposed to achieve oxidative cleavage of C(sp3)-H bonds, followed by decarboxylation and annulation. The mild reaction conditions employed in both cases enable the tolerance of a wide range of functional groups as well as high reaction efficiency.
- Hu, Ting,Yan, Hao,Liu, Xingxing,Wu, Chaoyang,Fan, Yuxing,Huang, Jing,Huang, Guosheng
-
supporting information
p. 2866 - 2869
(2015/12/18)
-
- N -Bromosuccinimide as a Brominating Agent for the Transformation of N -H (or N -Benzyl) Ketoaziridines into Oxazoles
-
A novel procedure for the direct synthesis of 2,5-diaryloxazoles starting from N-H ketoaziridines is described. The method proceeds via the in situ formation of N-bromoketoaziridines in the presence of N-bromosuccinimide followed by the generation of intermediate azomethine ylides. A plausible mechanism for this transformation is proposed.
- Samimi, Heshmat A.,Dadvar, Farkhondeh
-
p. 1899 - 1904
(2015/06/30)
-
- Iodine catalysed intramolecular C(sp3)-H functionalization: synthesis of 2,5-disubstituted oxazoles from N-arylethylamides
-
Iodine catalyzed synthesis of 2,5-disubstituted oxazoles from N-arylethylamides through intramolecular C(sp3)-H functionalization under metal-free conditions is described. The method is tolerable to a wide range of substrates having a variety of functional groups with moderate to good yields of the products.
- Samanta, Supravat,Donthiri, Ramachandra Reddy,Dinda, Milan,Adimurthy, Subbarayappa
-
p. 66718 - 66722
(2015/08/24)
-
- Synthesis and Catalytic Use of Gold(I) Complexes Containing a Hemilabile Phosphanylferrocene Nitrile Donor
-
Removal of the chloride ligand from [AuCl(1-κP)] (2) containing a P-monodentate 1′-(diphenylphosphanyl)-1-cyanoferrocene ligand (1), by using silver(I) salts affords cationic complexes of the type [Au(1)]X, which exist either as cyclic dimers [Au(1)]2X2 (3a, X=SbF6; 3 c, X=NTf2) or linear coordination polymers [Au(1)]nXn (3 a′, X=SbF6; 3 b′, X=ClO4), depending on anion X and the isolation procedure. As demonstrated for 3 a′, the polymers can be readily cleaved by the addition of donors, such as Cl-, tetrahydrothiophene (tht) or 1, giving rise to the parent compound 2, [Au(tht)(1-κP)][SbF6] (5 a) or [Au(1-κP)2][SbF6] (4 a), respectively, of which the last two compounds can also be prepared by stepwise replacement of tht in [Au(1-κP)2][SbF6]. The particular combination of a firmly coordinated (phosphane) and a dissociable (nitrile) donor moieties renders complexes 3/3′ attractive for catalysis because they can serve as shelf-stable precursors of coordinatively unsaturated AuI fragments, analogous to those that result from the widely used [Au(PR3)(RCN)]X catalysts. The catalytic properties of the Au-1 complexes were evaluated in model annulation reactions, such as the synthesis of 2,3-dimethylfuran from (Z)-3-methylpent-2-en-4-yn-1-ol and oxidative cyclisation of alkynes with nitriles to produce 2,5-disubstituted 1,3-oxazoles. Of the compounds tested (2, 3 a′, 3 b′, 3 a, 4 a and 5 a), the best results were consistently achieved with dimer 3 c, which has good solubility in organic solvents and only one firmly bound donor at the gold atom. This compound was advantageously used in the key steps of annuloline and rosefuran syntheses.
- ?koch, Karel,Císa?ová, Ivana,?těpni?ka, Petr
-
supporting information
p. 15998 - 16004
(2015/11/03)
-
- Reaction of alkynes and azides: Not triazoles through copper-acetylides but oxazoles through copper-nitrene intermediates
-
Well-defined copper(I) complexes of composition [Tpm* ,BrCu(NCMe)]BF4 (Tpm*,Br=tris(3,5- dimethyl-4-bromo-pyrazolyl)methane) or [Tpa* Cu]PF6 (Tpa=tris(3,5-dimethyl-pyrazolylmethyl)amine) catalyze the formation of 2,5-disubstituted oxazoles from carbonyl azides and terminal alkynes in a direct manner. This process represents a novel procedure for the synthesis of this valuable heterocycle from readily available starting materials, leading exclusively to the 2,5-isomer, attesting to a completely regioselective transformation. Experimental evidence and computational studies have allowed the proposal of a reaction mechanism based on the initial formation of a copper-acyl nitrene species, in contrast to the well-known mechanism for the copper-catalyzed alkyne and azide cycloaddition reactions (CuAAC) that is triggered by the formation of a copper-acetylide complex.
- Haldon, Estela,Besora, Maria,Cano, Israel,Cambeiro, Xacobe C.,Pericas, Miquel A.,Maseras, Feliu,Nicasio, M. Carmen,Perez, Pedro J.
-
supporting information
p. 3463 - 3474
(2014/04/03)
-
- Copper-catalyzed oxidative cyclization of chalcone and benzylic amine leading to 2,5-diaryl oxazoles via carbon-carbon double bond cleavage
-
A copper-catalyzed oxidative cyclization of chalcone with benzylic amine is achieved, providing 2,5-diaryl oxazoles in moderate to good yields. The procedure employs O2 as a clean oxidant and involves an oxidative cleavage of the CC bond as the key step.
- Liu, Dongfang,Yu, Jintao,Cheng, Jiang
-
p. 1149 - 1153
(2014/02/14)
-
- One-pot conversion of amino acids into 2,5-disubstituted oxazoles: No metals needed
-
2,5-Disubstituted oxazoles with a variety of alkyl and aryl groups are efficiently formed from N-acylamino acids, by a one-pot radical decarboxylation- oxidation-enolization and iodine-promoted cyclization process. Remarkably, the reaction takes place under mild conditions, and no metal catalysis is needed. The process can be useful for the direct modification of small peptides.
- Romero-Estudillo, Ivan,Batchu, Venkateswara Rao,Boto, Alicia
-
supporting information
p. 3742 - 3748
(2015/01/16)
-
- A photochemical one-pot three-component synthesis of tetrasubstituted imidazoles
-
Tetrasubstituted imidazoles can be formed in a photochemical one-pot synthesis from aldehydes, α-aminonitriles, and isoxazoles. Condensation of the first two components produces α-(alkylideneamino)nitriles which react under basic conditions with the acylazirines formed in situ by photochemical ring transformation of the isoxazole component. This process includes an unusual cleavage of the C2-C3 bond of the acylazirine. The reaction mechanism was studied by DFT calculations. (Chemical Equation Presented)
- Pusch, Stefan,Opatz, Till
-
p. 5430 - 5433
(2015/01/09)
-
- Direct C-H bond arylation of (benzo)oxazoles with aryl chlorides catalyzed by N-heterocyclic carbene-palladium(II)-1-methylimidazole complex
-
The direct C-H bond arylation of (benzo)oxazoles with aryl chlorides was achieved catalyzed by a well-defined NHC-Pd(II)-Im complex. Under the optimal conditions, various aryl chlorides were successfully applied as the arylating reagents to achieve the 2-aryl (benzo)oxazoles in acceptable to high yields, providing a convenient and alternative method for the direct C-H bond arylation of (benzo)oxazoles and enriching the chemistry of the NHC-Pd(II) complex in organic synthesis.
- Shen, Xiao-Bao,Zhang, Yun,Chen, Wen-Xin,Xiao, Zheng-Kang,Hu, Ting-Ting,Shao, Li-Xiong
-
supporting information
p. 1984 - 1987
(2014/05/06)
-
- Iodine(III)-promoted synthesis of oxazoles through oxidative cyclization of N -styrylbenzamides
-
The hypervalent iodine reagent PhI(OTf)2, generated in situ, has been successfully utilized in an intramolecular oxidative cyclization of N-styrylbenzamides. In remarkably short reaction times, the desired 2,5-disubstituted oxazoles were isolated in high yields in this metal-free oxidative C-O bond-forming reaction. Georg Thieme Verlag Stuttgart, New York.
- Hempel, Christian,Nachtsheim, Boris J.
-
p. 2119 - 2123
(2013/10/21)
-
- Practical oxazole synthesis mediated by iodine from α-bromoketones and benzylamine derivatives
-
The reagent system of I2/K2CO3 could efficiently promote the oxazole synthesis from α-bromoketones and benzylamine derivatives in DMF. This method was not only suitable for 2,5-diaryl oxazole synthesis but also for 2,4,5-trisubstituted oxazole and 5-alkyl/alkenyl oxazole synthesis. Furthermore, this method was successfully applied to a one-step synthesis of a natural product halfordinol in 62% yield.
- Gao, Wen-Chao,Wang, Ruo-Lin,Zhang, Chi
-
p. 7123 - 7128
(2013/10/22)
-
- I2/TBHP-mediated domino process: A convenient route to 1,3-oxazole derivatives
-
A practical and simple synthesis of 2,5-disubstituted oxazoles was developed via a TBHP (tert-butyl hydroperoxide)/I2-mediated domino strategy. The reaction proceeds in series, giving rise to the formation of an intermolecular C-N bond and an intramolecular C-O bond, which yield oxazole derivatives simultaneously. The reaction gave the desired products from readily available substrates under mild conditions.
- Feng, Cheng-Tao,Zhao, Ming,Ma, Shi-Tang,Qin, Xia
-
p. 3835 - 3841
(2013/10/22)
-
- Convenient one-pot synthesis of 2,5-disubstituted oxazoles via a catalytic oxidative dehydrogenation of F3CSO3H·SiO 2-DDQ/CuCl2/LiCl
-
A facile one-pot synthesis of 2,5-disubstituted oxazoles was developed via cyclization of aldoximes and phenylacetylene then dehydrogenation oxidation. 2,3-dichloro-5,6-dicyano-1,4-benzoquinone was studied for the selective oxidation of oxazolines using Cu2+/Li+ as catalyst and O2 as indirect oxidant. The reaction results showed that this catalyst system can effectively catalyze the oxidation of oxazolines to the corresponding oxazoles. Thus, a variety of polysubstituted oxazoles was easily synthesized in high yields by catalytic oxidation of 2,3-dichloro-5,6-dicyano-1, 4-benzoquinone/CuCl2/LiCl/O2.
- Yuan, Shizhen,Li, Zhen,Xu, Ling
-
p. 1405 - 1409
(2014/01/06)
-
- C-C bond cleavage of keto-aziridines; synthesis of oxazoles via regio-controlled ring expansion
-
The ring expansion of keto-aziridines to the corresponding 2,5-diaryloxazoles in the presence of iodine in refluxing dimethyl sulfoxide, is described. A plausible mechanism for the synthesis of 2,5-diaryloxazoles is proposed.
- Samimi, Heshmat Allah,Entezami, Soraya
-
p. 745 - 747
(2014/01/23)
-
- A new approach to ring expansion of keto aziridines to 2,5-diaryloxazoles
-
Ring expansion of keto aziridines to the corresponding 2,5-diaryl oxazoles in the presence of dicyclohexyl carbodiimide and iodine under refluxing acetonitrile conditions is described. A plausible mechanism is proposed. Georg Thieme Verlag Stuttgart New York.
- Samimi, Heshmat A.,Mohammadi, Somaye
-
supporting information
p. 223 - 225
(2013/03/13)
-
- Practical synthesis of polysubstituted imidazoles via iodine- Catalyzed aerobic oxidative cyclization of aryl ketones and benzylamines
-
A practical synthetic method for polysubstituted imidazoles via iodine-catalyzed aerobic oxidative cyclization of aryl ketones and benzylamines has been developed. It was found to tolerate a broad range of substrates to prepare polysubstituted imidazole derivatives in a one-pot manner, and thus importantly allowed product diversity for imidazole chemistry. Additionally, the resultant 1,2,4-trisubstituted imidazoles could be conveniently transformed to functionalized 1,2,4,5-tetrasubstituted imidazoles via electrophilic substitution or direct C-H functionalization, or 2,4-diaryl-1H-imidazoles by debenzylation reaction, which further indicates potential applications of this method in synthetic and pharmaceutical chemistry. Copyright
- Huang, Huawen,Ji, Xiaochen,Wu, Wanqing,Jiang, Huanfeng
-
p. 170 - 180
(2013/03/13)
-
- Metal-free dual sp3 C-H functionalization: I2- promoted domino oxidative cyclization to construct 2,5-disubstituted oxazoles
-
An I2-promoted sp3 C-H functionalization has been developed for the synthesis of 2,5-disubstituted oxazoles from easily available methyl ketones and benzylamines without any metal and peroxide catalyst. This domino oxidative cyclization process involves the cleavage of C-H bond and the formation of C-N, C-O bonds.
- Gao, Qing-He,Fei, Zhuan,Zhu, Yan-Ping,Lian, Mi,Jia, Feng-Cheng,Liu, Mei-Cai,She, Neng-Fang,Wu, An-Xin
-
-
- Synthesis of highly substituted oxazoles through iodine(III)-mediated reactions of ketones with nitriles
-
In the presence of trifluoromethanesulfonic acid (TfOH) or bis(trifluoromethanesulfonyl) imide (Tf2NH), iodosobenzene (PhI=O) efficiently promoted the reactions of dicarbonyl compounds as well as monocarbonyl compounds with nitriles to give 2,4-disubstituted and 2,4,5-trisubstituted oxazole in a single step under the mild conditions.
- Saito, Akio,Hyodo, Nao,Hanzawa, Yuji
-
supporting information
p. 11046 - 11055
(2012/11/07)
-
- Synthesis of 2,5-disubstituted oxazoles and oxazolines catalyzed by ruthenium(II) porphyrin and simple copper salts
-
A novel and moderate synthesis of 2,5-disubstituted oxazoles and oxazolines involving ruthenium(II) porphyrin-copper chloride catalyzed cyclization was developed. These reactions using readily available benzene carboxylic acids and phenylethenes or phenylacetylenes are performed under mild conditions. The reactions proceed in series, giving rise to the formation of an intermolecular C-N bond and an intramolecular C-O bond, which yield oxazole or oxazoline derivatives simultaneously.
- Zhong, Chuan Long,Tang, Bo Yang,Yin, Ping,Chen, Yue,He, Ling
-
experimental part
p. 4271 - 4277
(2012/06/18)
-
- Iron-promoted practical one-pot synthesis of 2,5-disubstituted oxazoles
-
A practical one-pot protocol for the synthesis of 2,5-disubstituted oxazoles from 1-aryl-2-nitroethanones was reported. In the presence of iron/AcOH in acetonitrile, the reaction of 1-aryl-2-nitroethanones with trimethyl orthoacetate or trimethyl orthobenzoate delivered the corresponding 2,5-disubstituted oxazoles in moderate to good yields. Copyright
- Chen, Songhui,Bai, Donghu,Shi, Feng,Li, Jian,Li, Chunju,Jia, Xueshun
-
experimental part
p. 1464 - 1468
(2012/09/07)
-
