- Solvent role in the lipase-catalysed esterification of cinnamic acid and derivatives. Optimisation of the biotransformation conditions
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The esterification of cinnamic acid has been deeply investigated using ethanol as nucleophile and Candida antarctica lipase type B (CAL-B) as suitable biocatalyst. Special attention has been paid to the role that the solvent plays in the production of ethyl cinnamate. Therefore, volatile organic solvents and deep eutectic mixtures were employed in order to find optimal reaction conditions. Once that hexane was selected as the solvent of choice, other parameters that affect the enzyme activity were investigated in order to produce ethyl cinnamate with excellent yield. The CAL-B loading, nucleophile equivalents, temperature and reaction time have been identified as key parameters in the enzyme efficiency, and the potential of lipase-catalysed esterification has been finally exploited to produce a series of ethyl esters with different pattern substitutions on the aromatic ring.
- Suárez-Escobedo, Laura,Gotor-Fernández, Vicente
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- Hypervalent iodine(iii) induced oxidative olefination of benzylamines using Wittig reagents
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We have developed hypervalent iodine(iii) induced oxidative olefination of primary and secondary benzylamines using 2C-Wittig reagents, which provides easy access to α,β-unsaturated esters. Mild reaction conditions, good to excellent yields with high (E) selectivity, and a broad substrate scope are the key features of this reaction. We have successfully carried out the gram-scale synthesis of α,β-unsaturated esters.
- Ramavath, Vijayalakshmi,Rupanawar, Bapurao D.,More, Satish G.,Bansode, Ajay H.,Suryavanshi, Gurunath
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p. 8806 - 8813
(2021/05/26)
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- Regio- And diastereoselective Pd-catalyzed aminochlorocyclization of allylic carbamates: scope, derivatization, and mechanism
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The regio- and diastereoselective synthesis of oxazolidinonesviaa Pd-catalyzed vicinal C-N/C-Cl bond-forming reaction from internal alkenes of allylic carbamates is reported. The oxazolidinones are obtained in yields of 44 to 95% with high to excellent diastereoselectivities (from 6?:?1 to >20?:?1 dr) from readily available precursors. This process is scalable, and the products are suitable for the synthesis of useful amino alcohols. A detailed theoretical and experimental mechanistic study was carried out to describe that the reaction proceeds through ananti-aminopalladation of the alkene followed by an oxidative C-Pd(ii) cleavage with retention of the carbon stereochemistry to yield the major diastereomer. The role of Cu(ii) in a C-Cl bond-forming mechanism step has also been proposed.
- Ariga, Elaine Miho,Carita Correra, Thiago,Matsushima, Jullyane Emi,McIndoe, J. Scott,Moreira Ribeiro, Francisco Wanderson,Omari, Isaac,Papa Spadafora, Bruna,Rodrigues, Alessandro,Soares, Priscila Machado Arruda,Vinhato, Elisangela,de Oliveira-Silva, Diogo
-
supporting information
p. 5595 - 5606
(2021/07/02)
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- Selective Synthesis of Z-Cinnamyl Ethers and Cinnamyl Alcohols through Visible Light-Promoted Photocatalytic E to Z Isomerization
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A photocatalytic E to Z isomerization of alkenes using an iridium photosensitizer under mild reaction conditions is disclosed. This method provides scalable and efficient access to Z-cinnamyl ether and allylic alcohol derivatives in high yields with excellent stereoselectivity. Importantly, this method also provides a powerful strategy for the selective synthesis of Z-magnolol and honokiol derivatives possessing potential biological activity.
- Li, Hengchao,Chen, Hang,Zhou, Yang,Huang, Jin,Yi, Jundan,Zhao, Hongcai,Wang, Wei,Jing, Linhai
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supporting information
p. 555 - 559
(2020/02/05)
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- Dual ligand-promoted palladium-catalyzed nondirected C-H alkenylation of aryl ethers
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Direct C-H functionalization of aryl ethers remains challenging owing to their low reactivity and selectivity. Herein, a novel strategy for nondirected C-H alkenylation of aryl ethers promoted by a dual ligand catalyst was demonstrated. This catalytic system readily achieved the highly efficient alkenylation of alkyl aryl ethers (anisole, phenetole, n-propyl phenyl ether, n-butyl phenyl ether and benzyl phenyl ether), cyclic aryl ethers (1,4-benzodioxan, 2,3-dihydrobenzofuran, dibenzofuran), and diphenyl oxides. Moreover, the proposed methodology was successfully employed for the late-stage modification of complex drugs containing the aryl ether motif. Interestingly, the compounds developed herein displayed fluorescent properties, which would facilitate their biological applications.
- Fu, Manlin,Liu, Jiang,Wang, Lei,Yin, Biao,Zhu, Qing
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supporting information
p. 3293 - 3296
(2020/04/02)
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- Highly active homoleptic nickel(II) bis-N-heterocyclic carbene catalyst for Suzuki–Miyaura and Heck cross-coupling reactions
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New homoleptic nickel(II) biscarbene complex was synthesized and structurally characterized. The complex depicted the excellent catalytic activities with only 3 mol% catalyst loading along with wide substrate scope for the Suzuki–Miyaura cross-coupling reactions (twenty six examples) and Heck coupling reactions (eighteen examples).
- Nirmala, Muthukumaran,Arruri, Sathyanarayana,Vaddamanu, Moulali,Karupnaswamy, Ramesh,Mannarsamy, Maruthupandi,Adinarayana, Mannem,Ganesan, Prabusankar
-
supporting information
p. 125 - 134
(2018/11/23)
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- Bis(pyrazolyl)palladium(II) complexes as catalysts for Mizoroki–Heck cross-coupling reactions
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Recent progress in carbon–carbon cross-coupling reactions has resulted in the discovery of highly active catalysts for carrying out such transformations. However, due to the wide array of applications of the products from cross-coupling reactions, there is the need to design suitable catalysts that permit the practical and economical synthesis of the cross-coupled products. Palladium complexes with bulky and electron-donating ligands have served as excellent (pre)catalysts for the Mizoroki–Heck cross-coupling reaction. By using bulky pyrazole-based ligands, we have prepared palladium(II) complexes with controlled steric and electronic properties of the metal center. We have used these bulky bis(pyrazolyl)palladium(II) complexes as (pre)catalysts for the Mizoroki–Heck cross-coupling reaction. The (pre)catalysts displayed high activity and selectivity, giving high catalytic conversions at a low (pre)catalyst loading and short reaction times. A mercury poisoning test confirmed that the (pre)catalysts promoted the Mizoroki–Heck cross-coupling homogenously and do not decompose into palladium black during the reactions. The catalytic systems were also tolerant to the presence of functional groups, such as 4-CF3, 4-CH3, 4-CO2Me and 4-CO2Et, on the alkene substrates.
- Ocansey, Edward,Darkwa, James,Makhubela, Banothile C.E.
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- Rh-Catalyzed Asymmetric Conjugate Addition of Arylboronic Acids to 3-Arylpropenoates: Enantioselective Synthesis of (R)-Tolterodine
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A highly enantioselective conjugate addition of arylboronic acids to 3-arylpropenoates is presented. The rhodium complexes obtained from deoxycholic acid derived binaphthyl phosphites showed good activity as well as very high enantioselectivity (ee up to 99 %) in the conjugate addition to different ethyl-3-arylpropenoates, allowing to obtain useful chiral building blocks for the synthesis of active pharmaceutical ingredients. The method was applied to the enantioselective synthesis of the antimuscarinic drug (R)-tolterodine.
- Zullo, Valerio,Iuliano, Anna
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supporting information
p. 1377 - 1384
(2019/01/04)
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- Facile synthesis of α, β-unsaturated esters through a one-pot copper-catalyzed aerobic oxidation-Wittig reaction
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An efficient one-pot synthesis of α, β-unsaturated esters through the aerobic oxidation – Wittig tandem reaction of alcohols and phosphorous ylide is developed. This new method operates under mild reaction conditions, and uses CuI/TEMPO (TEMPO = 2,2,6,6-tetramethylpiperidine-N-oxyl) as co-catalyst and air (O2) as the oxidant. It tolerates a wide range of functionalized benzylic alcohol and aliphatic alcohols.
- Ren, Cheng,Shi, Zhenyu,Ding, Weijie,Liu, Zhiqing,Jin, Huile,Yu, Xiaochun,Wang, Shun
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supporting information
p. 14 - 17
(2017/12/06)
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- Rh(III)-Catalyzed Enaminone-Directed C-H Coupling with α-Diazo-α-phosphonoacetate for Reactivity Discovery: Fluoride-Mediated Dephosphonation for C-C Coupling Reactions
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Rh(III)-catalyzed enaminone-directed C-H coupling with α-diazo-α-phosphonoacetate has been used for the identification of fluoride-mediated dephosphonation C-C coupling reactivity for the synthesis of 4-hydroxy-1-naphthoates. Intermolecular C-C coupling of α-phosphonoacetate and benzaldehyde for (E)-selective α,β-unsaturated ester synthesis has also been achieved.
- Song, Chao,Yang, Chen,Zeng, Hua,Zhang, Wenjing,Guo, Shan,Zhu, Jin
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supporting information
p. 3819 - 3823
(2018/07/22)
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- One-Pot Synthesis of α,β-Unsaturated Esters, Ketones, and Nitriles from Alcohols and Phosphonium Salts
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A general method for the synthesis of α,β-unsaturated esters, ketones, and nitriles is successfully achieved by a one-pot copper-catalyzed oxidation with O 2 in air as oxidant. The solvent mixture of acetonitrile and formamide (1:1) is optimized to ensure the oxidation of alcohols, deprotonation of phosphonium salt, and Wittig reaction occur efficiently in one pot. A broad range of substrates has been explored for this process, including three electron-withdrawing group (CO 2 Et, COPh, CN) functionalized phosphonium salts. They reacted not only with benzylic and heteroaromatic alcohols, but also with aliphatic alcohols, forming the corresponding α,β-unsaturated esters, ketones, and nitriles in moderate to excellent yields.
- Ding, Weijie,Hu, Juan,Jin, Huile,Yu, Xiaochun,Wang, Shun
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p. 107 - 118
(2017/09/28)
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- Silica-coated nano-Fe3O4-supported iminopyridine palladium complex as an active, phosphine-free and magnetically separable catalyst for Heck reactions
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A novel magnetic nanoparticle-supported iminopyridine palladium complex was successfully prepared by attaching palladium acetate to iminopyridine ligand-functionalized silica-coated nano-Fe3O4. The as-prepared catalyst was well characterized and was evaluated in Heck reactions in terms of activity and recyclability. It was found to be highly efficient for the reactions of various aryl iodides and aryl bromides having electron-withdrawing groups with olefins under phosphine-free and inert atmosphere-free conditions. Moreover, the catalyst could be conveniently recovered using an external magnet, and the recyclability was influenced by the base in the Heck reaction. The catalyst could be reused at least six times with no significant loss in activity when triethylamine acted as the base.
- Zhang, Qiang,Zhao, Xin,Wei, Huai-Xin,Li, Ji-Hang,Luo, Jun
-
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- Nucleophilic Amination of Methoxy Arenes Promoted by a Sodium Hydride/Iodide Composite
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A method for the nucleophilic amination of methoxy arenes was established by using sodium hydride (NaH) in the presence of lithium iodide (LiI). This method offers an efficient route to benzannulated nitrogen heterocycles. Mechanistic studies showed that the reaction proceeds through an unusual concerted nucleophilic aromatic substitution.
- Kaga, Atsushi,Hayashi, Hirohito,Hakamata, Hiroyuki,Oi, Miku,Uchiyama, Masanobu,Takita, Ryo,Chiba, Shunsuke
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supporting information
p. 11807 - 11811
(2017/09/20)
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- Piperlongumine derived cyclic sulfonamides (sultams): Synthesis and in?vitro exploration for therapeutic potential against HeLa cancer cell lines
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A novel modification of piperlongumine is designed, bearing a cyclic sulphonamide (sultam) and its synthesis is described. For the first time herein we report the synthesis and biological evaluation of the natural product derived cyclic sulfonamides using Grubbs second generation catalyst (Grubbs II) via ring closing metathesis approach. Synthesis of a series of piperlongumine derived sultams is done in a moderate to good yield using Wittig reaction, Ring-Closing Metathesis (RCM) and, amide synthesis by using mixed anhydride, approach. All synthesized compounds were evaluated for anticancer activity and some demonstrated dose dependent reduction in HeLa cell growth. Of these 7, 10 and 14 significantly reduced the cell growth. Consequently their calculated GI50values were found to be 0.1 or 0.1?μM.
- Lad, Nitin P.,Kulkarni, Sarang,Sharma, Rajiv,Mascarenhas, Malcolm,Kulkarni, Mahesh R.,Pandit, Shivaji S.
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p. 870 - 878
(2016/12/18)
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- N-heterocyclic carbene-catalysed Peterson olefination reaction
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N-heterocyclic carbenes (NHCs) have been utilised as highly efficient organocatalysts to catalyse Peterson olefination reaction of aldehydes with trimethylsilylketene ethyl trimethylsilyl acetal or fluoro(trimethylsilyl)ketene ethyl trimethylsilyl acetal to produce the corresponding functionalized olefines in 34-93% yields with excellent stereoselectivities.
- Wang, Ying,Du, Guang-Fen,Gu, Cheng-Zhi,Xing, Fen,Dai, Bin,He, Lin
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p. 472 - 478
(2015/12/31)
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- Trans-cinnamic acid ester compound and its synthetic method and application
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The invention relates to a trans cinnamic acid ester compound, as well as a synthetic method and application thereof. At present, a typic miticide has the growing problems, such as drug resistance and environment and ecology, so that a new animal miticide needs to be developed very urgently. The trans cinnamic acid ester compound has the molecular structure shown in the specification, wherein R refers to alkyl radical, R1 and R2 refer to hydrogen, hydroxide radical, alkyl radical, alkoxy, fatty acyloxy, halogen, methylenedioxy or nitro, and are the same or different; the trans cinnamic acid ester compound can be used for preparing miticides for animals and people. The compound serves as a novel miticide, is relatively low in toxicity, small in molecular weight, few in synthetic steps, simple to operate, low in production cost, and suitable for large-scale industrial production; the acaricidal activity is remarkably stronger that of a miticide applied in current all clinics.
- -
-
Paragraph 0069; 0070
(2016/10/07)
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- Design and synthesis of a series of serine derivatives as small molecule inhibitors of the SARS coronavirus 3CL protease
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Synthesis of serine derivatives having the essential functional groups for the inhibitor of SARS 3CL protease and evaluation of their inhibitory activities using SARS 3CL R188I mutant protease are described. The lead compounds, functionalized serine derivatives, were designed based on the tetrapeptide aldehyde and Bai's cinnamoly inhibitor, and additionally performed with simulation on GOLD softwear. Structure activity relationship studies of the candidate compounds were given reasonable inhibitors ent-3 and ent-7k against SARS 3CL R188I mutant protease. These inhibitors showed protease selectivity and no cytotoxicity.
- Konno, Hiroyuki,Wakabayashi, Masaki,Takanuma, Daiki,Saito, Yota,Akaji, Kenichi
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p. 1241 - 1254
(2016/03/01)
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- Ligand-Free Heck Reactions of Aryl Iodides: Significant Acceleration of the Rate through Visible Light Irradiation at Ambient Temperature
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A mild Heck reaction of aryl iodides and olefins was realized by the cooperation of a palladium and a photoredox catalyst under the irradiation of visible light. This protocol works well to synthesize stilbenes with high Z/E ratios and (E)-cinnamates in the absence of ligands at ambient temperature. Control experiments revealed that palladium salt, visible light and photoredox catalyst were all crucial for the achievement of this cross-coupling under mild conditions. (Figure presented.).
- Zhang, Heng,Huang, Xueliang
-
supporting information
p. 3736 - 3742
(2016/12/16)
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- Ketenimines from Isocyanides and Allyl Carbonates: Palladium-Catalyzed Synthesis of β,γ-Unsaturated Amides and Tetrazoles
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The reaction of allyl ethyl carbonates with isocyanides in the presence of a catalytic amount of Pd(OAc)2provided ketenimines through β-hydride elimination of the allyl imidoylpalladium intermediates. The insertion of the isocyanide into the π-allyl Pd complex proceeded via an unusual η1-allyl Pd species. The resulting ketenimines were hydrolyzed to β,γ-unsaturated carboxamides during purification by flash column chromatography on silica gel or converted in situ into 1,5-disubstituted tetrazoles by [3+2] cycloaddition with hydrazoic acid or trimethylsilyl azide.
- Qiu, Guanyinsheng,Mamboury, Mathias,Wang, Qian,Zhu, Jieping
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supporting information
p. 15377 - 15381
(2016/12/06)
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- BF3·OEt2-mediated: Syn -selective Meyer-Schuster rearrangement of phenoxy propargyl alcohols for Z -β-aryl-α,β-unsaturated esters
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Synthesis of Z-β-aryl-α,β-unsaturated esters from readily available 1-aryl-3-phenoxy propargyl alcohols is achieved via a BF3-mediated syn-selective Meyer-Schuster rearrangement under ambient conditions. The reaction mechanism is postulated to involve an electrophilic borylation of an allene intermediate as the key step to kinetically control the stereoselectivity.
- Puri, Surendra,Hari Babu, Madala,Sridhar Reddy, Maddi
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p. 7001 - 7009
(2016/07/30)
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- Iron(IV)-Corrole Catalyzed Stereoselective Olefination of Aldehydes with Ethyl Diazoacetate
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Iron(IV)-corrole complexes were first investigated as catalysts for olefination of aldehydes with ethyl diazoacetate in the presence of triphenylphosphine. Efficient olefination of aromatic aldehydes with high trans-selectivity was observed, showing iron corrole is a new kind of promising catalyst for olefination reaction. Transformation of the phosphazine to ylide by iron(IV) corrole was proved to be the key step in the present system.
- Zou, Huai-Bo,Yang, Hong,Liu, Ze-Yu,Mahmood, Mian H.R.,Mei, Guang-Quan,Liu, Hai-Yang,Chang, Chi-Kwong
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supporting information
p. 2791 - 2795
(2015/06/30)
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- Ethyl cinnamate derivatives as promising high-efficient acaricides against Psoroptes cuniculi: Synthesis, bioactivity and structure-activity relationship
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This paper reported the synthesis, structure-activity relationship (SAR) and acaricidal activity in vitro against Psoroptes cuniculi, a mange mite, of 25 ethyl cinnamate derivatives. All target compounds were synthesized and elucidated by means of MS, 1H- and 13C-NMR analysis. The results showed that 24 out of 25 tested compounds at 1.0 mg/mL demonstrated acaricidal activity in varying degrees. Among them, 6, 15, 26, 27 and 30 showed significant activity with median lethal concentration values (LC50) of 89.3, 119.0, 39.2, 29.8 and 41.2 μg/mL, respectively, which were 2.1- to 8.3-fold the activity of ivermectin (LC50=247.4 μg/mL), a standard drug in the treatment of Psoroptes cuniculi. Compared with ivermectin, with a median lethal time value (LT50) of 8.9 h, 27 and 30 showed smaller LTM50 values of 7.9 and 1.3 h, respectively, whereas 6, 15 and 26 showed slightly larger LT50 values of 10.6, 11.0 and 10.4 h at 4.5 μmol/mL. SARs showed that the presence of o-NO2 or m-NO2 on the benzene ring significantly improved the activity, whereas the introduction of a hydroxy, methoxy, acetoxy, methylenedioxy, bromo or chloro group reduced the activity. (E)-Cinnamates were more effective than their (Z)-isomer. Nevertheless, the carbon-carbon double bond in the acrylic ester moiety was proven not to be essential to improve the activity of cinnamic acid esters. Thus, the results strongly indicate that cinnamate derivatives, especially their dihydro derivatives, should be promising candidates or lead compounds for the development of novel acaricides for the effective control of animal or human acariasis.
- Zhang, Bingyu,Lv, Chao,Li, Weibo,Cui, Zhiming,Chen, Dongdong,Cao, Fangjun,Miao, Fang,Zhou, Le
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p. 255 - 262
(2015/04/22)
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- An isothiourea-catalyzed asymmetric [2,3]-rearrangement of allylic ammonium ylides
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Benzotetramisole promotes the catalytic asymmetric [2,3]-rearrangement of allylic quaternary ammonium salts (either isolated or prepared in situ from p-nitrophenyl bromoacetate and the corresponding allylic amine), generating syn-α-amino acid derivatives with excellent diastereo- and enantioselectivity (up to >95:5 dr; up to >99% ee).
- West, Thomas H.,Daniels, David S. B.,Slawin, Alexandra M. Z.,Smith, Andrew D.
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supporting information
p. 4476 - 4479
(2014/04/17)
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- Aldehyde-Assisted Ruthenium(II)-Catalyzed C-H Oxygenations
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Versatile ruthenium(II) complexes allow for site-selective C-H oxygenations with weakly-coordinating aldehydes. The challenging C-H functionalizations proceed with high chemoselectivity by rate-determining C-H metalation. The new method features an ample substrate scope, which sets the stage for the step-economical preparation of various bioactive heterocycles.
- Yang, Fanzhi,Rauch, Karsten,Kettelhoit, Katharina,Ackermann, Lutz
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supporting information
p. 11285 - 11288
(2016/02/18)
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- Palladium chloride catalyzed photochemical Heck reaction
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PdCl2 catalyzed carbon-carbon bond formation (Heck reaction) between substituted aryl halides and olefins was carried out without a ligand, under irradiation with UV-visible light. The results demonstrated that UV-visible light accelerated the rate of the reaction, leading to an excellent yield of corresponding products. The recovered palladium nanoparticles could be thermally recycled several times. PdCl2 gave excellent conversion up to the fifth addition of substrate.
- Waghmode, Suresh B.,Arbuj, Sudhir S.,Wani, Bina N.,Gopinath
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supporting information
p. 348 - 351
(2013/06/04)
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- One-pot access to cinnamates via direct oxidative c-h transformation of allylarenes
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A highly selective combination of ruthenium complex and oxidant, which catalyzes the oxidative C-H esterification of allylarenes to the corresponding bis-(E)-cinnamates and (E)-cinnamates, is described. The one-pot route was carried out by olefinic migration of allylarenes with RuCl2(PPh 3)3 and DDQ-mediated allylic oxidation of the resulting internal alkenes with various alcohols in good yields. Georg Thieme Verlag Stuttgart · New York.
- Chang, Meng-Yang,Lin, Shin-Ying,Chan, Chieh-Kai
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p. 487 - 490
(2013/04/10)
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- Synthesis of a novel 8-hydroxyquinoline functionalized poly (ethylene glycol) bridged dicationic ionic liquid and its application in palladium-catalyzed Heck reaction under solvent-free conditions
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A novel 8-hydroxyquinoline functionalized poly (ethylene glycol) bridged dicationic ionic liquid ([HQ-PEG1000-DIL][BF4]) was synthesized and characterized. It was applied as an efficiently recyclable ligand for Pd-catalyzed Heck reaction under solvent-free conditions. It is noteworthy that the Pd(OAc)2/[HQ-PEG1000-DIL][BF 4] catalytic system could be easily recovered and reused without obvious loss of catalytic activity after five recycling runs.
- Wang, Yinglei,Luo, Jun,Liu, Zuliang
-
-
- Heterogeneous photocatalysed Heck reaction over PdCl2/TiO 2
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The heterogeneous PdCl2/TiO2 efficiently catalyzes the C-C bond formation (Heck reaction) between aryliodides and olefins under photochemical and mild reaction conditions. This process gives good to excellent conversion under optimized reaction conditions. After completion of the reaction, Pd2+ is reduced to Pd0. Further, Pd0 can be easily converted into Pd2+ by heating with ammonium chloride at 400°C for 30 min and the regenerated catalyst could be reused up to the third recycle with good catalytic activity. The catalysts (before and after reaction, as well as regenerated) were systematically characterized using Transmission Electron Microscopy, X-ray photoelectron spectroscopy, X-ray diffraction, temperature programmed reduction and DRUV-visible spectroscopy techniques.
- Waghmode, Suresh B.,Arbuj, Sudhir S.,Wani, Bina N.
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p. 2911 - 2916
(2013/09/12)
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- Rhodium-catalyzed olefin isomerization/allyl claisen rearrangement/ intramolecular hydroacylation cascade
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It has been established that a cationic Rh(I)/dppf complex catalyzes the olefin isomerization/allyl Claisen rearrangement/intramolecular hydroacylation cascade of di(allyl) ethers to produce substituted cyclopentanones in good yields under mild conditions.
- Okamoto, Ryuichi,Tanaka, Ken
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supporting information
p. 2112 - 2115
(2013/06/05)
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- Stereoselective olefination and regiospecific vicinal difunctionalization of imines with α-(benzothiazol-2-ylsulfonyl) carbonyl compounds
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Depending on their structures, imines are able to undergo either olefination or vicinal difunctionalization with various α-(benzothiazol-2- ylsulfonyl) carbonyl compounds in the absence of external bases. The olefination reaction of aromatic imines with α-(benzothiazol-2-ylsulfonyl) carbonyl compounds proceeds smoothly in tetrahydrofuran at 70 °C to give structurally diverse α,β-unsaturated esters, amides, and ketones in good to excellent yields and with extremely high (E) selectivity. In contrast, the carbon-nitrogen double bonds of cyclic imines and the carbon-carbon double bonds of α,β-unsaturated imines are subjected to regiospecific vicinal difunctionalization with α-(benzothiazol-2-ylsulfonyl) carbonyl compounds under the same reaction conditions to give a variety of benzothiazole derivatives in good to excellent yields. It is noteworthy that the benzothiazole moiety is present in a number of antitumor agents and bioluminescent molecules. In addition, plausible reaction pathways have been proposed to account for these transformations, and these are substantially supported by ESI-MS analysis of the reaction mixtures.
- Shao, You-Dong,Wu, Xue-Song,Tian, Shi-Kai
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supporting information; experimental part
p. 1590 - 1596
(2012/05/07)
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- Solid supported palladium(0) nano/microparticle: A ligand-free efficient recyclable heterogeneous catalyst for mono- and β,β-double-Heck reaction
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Solid supported palladium nano/microparticles were found to be active catalysts to perform mono- and β,β-double-Heck reactions. Different β-unsubstituted and substituted alkenes including acrylate, methacrylate, crotonate, styrene, acrylonitrile, and acrylamide were investigated successfully for mono- and β,β-double-Heck reactions with aryl iodide under milder reaction condition. One-pot β,β-double-Heck reaction of aryl iodides with α,β-unsaturated ester, amide, nitrile, and styrene derivatives were also performed under standard reaction conditions. Wide functional group tolerance, easy catalyst recovery, and recyclability up to twelve times without significant loss of catalytic activity added extra importance to the present process.
- Sharma, Dharminder,Kumar, Sandeep,Shil, Arun K.,Guha, Nitul Ranjan,Bandna,Das, Pralay
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supporting information
p. 7044 - 7051
(2013/01/15)
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- Pyridine ligands as promoters in PdII/0-catalyzed C-H olefination reactions
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Commercially available pyridine ligands can significantly enhance the rate, yield, substrate scope, and site selectivity of arene C-H olefination (Fujiwara-Moritani) reactions. The use of a 1:1 ratio of Pd/pyridine proved critical to maximize reaction rates and yields.
- Kubota, Asako,Emmert, Marion H.,Sanford, Melanie S.
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supporting information; experimental part
p. 1760 - 1763
(2012/05/20)
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- Unequivocal experimental evidence for a unified lithium salt-free wittig reaction mechanism for all phosphonium ylide types: Reactions with β-heteroatom-substituted aldehydes are consistently selective for cis-oxaphosphetane-derived products
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The true course of the lithium salt-free Wittig reaction has long been a contentious issue in organic chemistry. Herein we report an experimental effect that is common to the Wittig reactions of all of the three major phosphonium ylide classes (non-stabilized, semi-stabilized, and stabilized): there is consistently increased selectivity for cis-oxaphosphetane and its derived products (Z-alkene and erythro-β-hydroxyphosphonium salt) in reactions involving aldehydes bearing heteroatom substituents in the β-position. The effect operates with both benzaldehydes and aliphatic aldehydes and is shown not to operate in the absence of the heteroatom substituent on the aldehyde. The discovery of an effect that is common to reactions of all ylide types strongly argues for the operation of a common mechanism in all Li salt-free Wittig reactions. In addition, the results are shown to be most easily explained by the [2+2] cycloaddition mechanism proposed by Vedejs and co-workers as supplemented by Aggarwal, Harvey, and co-workers, thus providing strong confirmatory evidence in support of that mechanism. Notably, a cooperative effect of ortho-substituents in the case of semi-stabilized ylides is confirmed and is accommodated by the cycloaddition mechanism. The effect is also shown to operate in reactions of triphenylphosphine-derived ylides and has previously been observed for reactions under aqueous conditions, thus for the first time providing evidence that kinetic control is in operation in both of these cases.
- Byrne, Peter A.,Gilheany, Declan G.
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supporting information; experimental part
p. 9225 - 9239
(2012/07/14)
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- Organocatalytic decarboxylative Doebner-Knoevenagel reactions between arylaldehydes and monoethyl malonate mediated by a bifunctional polymeric catalyst
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A bifunctional polystyrene bearing both DMAP and piperidine groups has been prepared and used as an organocatalyst for decarboxylative Doebner-Knoevenagel reactions of arylaldehydes and monoethyl malonate. Isolated yields of the resulting cinnamates were very high, and in all cases only the E-isomer was detected. When a polystyrene catalyst functionalized with only DMAP or piperidine groups was used in these reactions, catalysis was much less efficient. Furthermore, catalysis using a combination of the monofunctional polymers was also less efficient than with the bifunctional polystyrene. Thus, it appears that there is a synergistic effect obtained by co-locating the two different catalytic amine groups on the same polymer backbone. Georg Thieme Verlag Stuttgart · New York.
- Lu, Jinni,Toy, Patrick H.
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supporting information; experimental part
p. 1723 - 1726
(2011/09/12)
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- On the stereoselective bicyclization of aminodienes catalyzed by chelating diamide complexes of the group 3 metals. A direct comparison of Sc(iii) and Y(iii) bis(amide)s with an application to the synthesis of alkaloid 195F
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Highly diastereoselective bicyclizations of aminodienes catalyzed by chelating diamide complexes of Sc(iii) and Y(iii) that lead to pyrrolizidines and indolizidines are described. This bis(annulation) procedure has been utilized in a concise synthesis of the pyrrolizidine alkaloid 195F.
- Jiang, Tao,Livinghouse, Tom,Lovick, Helena M.
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supporting information; experimental part
p. 12861 - 12863
(2012/02/02)
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- Effect of phase transfer chemistry, segmented fluid flow, and sonication on the synthesis of cinnamic esters
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Wittig reaction under Phase Transfer conditions was performed in a flow reaction system. Different bases, aldehydes, phosphonium salts, and flow reaction parameters were investigated, in absence of a phase transfert catalyst. An improvement of the reaction outcome (yield and reaction time) was achieved through the immersion of the reactor into an ultrasound bath.
- Riccaboni, Mauro,La Porta, Elena,Martorana, Andrea,Attanasio, Roberta
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experimental part
p. 4032 - 4039
(2010/07/06)
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- Expedient access to branched allylic silanes by copper-catalysed allylic substitution of linear allylic halides
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An unprecedented copper-catalysed allylic transposition enables the regioselective synthesis of branched allylic silanes from linear allylic halides through direct C-Si bond formation.
- Vyas, Devendra J.,Oestreich, Martin
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supporting information; experimental part
p. 568 - 570
(2010/05/01)
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- Sodium 2-(2-pyridin-3-ylethylamino)sulfonate: an efficient ligand and base for palladium-catalyzed Heck reaction in aqueous media
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The first successful Pd(OAc)2, N-donor ligand and base mediated Heck coupling reaction of aryl halides and alkenes in water is described. The corresponding Heck products were obtained in good to excellent yields.
- Pawar, Shivaji S.,Dekhane, Deepak V.,Shingare, Murlidhar S.,Thore, Shivaji N.
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p. 4252 - 4255
(2008/09/21)
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- Phosphine-free Pd-salen complexes as efficient and inexpensive catalysts for Heck and Suzuki reactions under aerobic conditions
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Phosphine-free palladium-salen complexes, N,N′-bis(salicylidene)-ethylenediamino-palladium and N,N′-bis(salicylidene)-1,2-phenylenediamino palladium, are found to be highly active catalysts for the Heck olefination of aryl iodides and Suzuki reaction of aryl iodides and bromides giving excellent yields (70-90%) of products under aerobic conditions, in short reaction times (10-60 min).
- Borhade, Sanjay R.,Waghmode, Suresh B.
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p. 3423 - 3429
(2008/09/21)
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- Heck reaction over palladium supported on nickel ferrite as an efficient and inexpensive catalyst
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The palladium supported on nickel ferrite found to be highly active catalyst for the Heck olefination of aryl iodides and activated aryl bromides providing an excellent yield in an aerobic condition, in shorter reaction time.
- Borhade, Sanjay R.,Waghmode, Suresh B.
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experimental part
p. 1549 - 1554
(2009/04/07)
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- Development of biisoquinoline-based chiral diaminocarbene ligands: Enantioselective SN2′ allylic alkylation catalyzed by copper-carbene complexes
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Chiral biisoquinoline-based diaminocarbene ligands (BIQ) were designed to create a chiral environment extended toward the metal center, which was confirmed by an X-ray structure. The concise ligand synthesis is highlighted by a modified Bischler-Napieralski cyclization of bisamides prepared from readily available chiral phenethylamines, and allows easy variation of the stereodifferentiating groups. The cyclohexyl-BIQ-copper complex is an efficient catalyst for enantioselective SN2′ allylic alkylation with Grignard reagents showing SN2′ regioselectivity higher than 5:1 and enantioselectivity in the range of 68-77% ee.
- Seo, Hwimin,Hirsch-Weil, Dimitri,Abboud, Khalil A.,Hong, Sukwon
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p. 1983 - 1986
(2008/09/19)
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- Arenediazonium o-benzenedisulfonimides as efficient reagents for Heck-type arylation reactions
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Arenediazonium o-benzenedisulfonimides can be used as new and efficient reagents for Heck-type arylation reactions of some common substrates containing C-C multiple bonds, namely ethyl acrylate, acrylic acid, acroleyne, styrene and cyclopentene. The reactions were carried out in an organic solvent, in the presence of Pd(OAc)2 as pre-catalyst, and gave rise to arylated products, for example, ethyl cinnamates, cinnamic acids, cinnamic aldehydes and stilbenes, possessing an (E)-configuration, and 1-arylcyclopentenes, in good to excellent yields. It is noteworthy that all the reactions led to the recovery, in greater than 80% yield, of o-benzenedisulfonimide, recyclable for the preparation of other diazonium salts.
- Artuso, Emma,Barbero, Margherita,Degani, Iacopo,Dughera, Stefano,Fochi, Rita
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p. 3146 - 3157
(2007/10/03)
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- Pd(OAc)2-Catalyzed Oxidative Coupling Reaction of Benzenes with Olefins in the Presence of Molybdovanadophosphoric Acid under Atmospheric Dioxygen and Air
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The direct oxidative coupling reaction of benzenes with alkenes bearing an electron-withdrawing group was successfully achieved by the use of Pd(OAc) 2/molybdovanadophosphoric acid (HPMoV) as the key catalyst under O2 or air atmosphere. Thus, the reaction of benzene with ethyl acrylate under air (1 atm) assisted by Pd(OAc)2/HPMoV afforded ethyl cinnamate as a major product in satisfactory yield (74%). This catalytic system could be extended to the coupling reactions between various substituted benzenes and alkenes through the direct aromatic C-H bond activation. In the reaction of benzene with ethyl acrylate under O2 (1 atm), the best turn-over number (TON) of Pd(OAc)2 reached was 121. This reaction provides a green route to cinnamate derivatives, which are important precursors of a variety of pharmaceuticals.
- Tani, Masayuki,Sakaguchi, Satoshi,Ishii, Yasutaka
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p. 1221 - 1226
(2007/10/03)
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- Wadsworth-Emmons reaction: The unique catalytic reaction by a solid base
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The near-stoichiometric amount of bases is used both in laboratory and industry in Wadsworth-Emmons (WE) reactions, since the by-product, (EtO) 2P(O)OH, formed in the reaction neutralizes the base into an inert salt. A strategy to design, develop, and evolve the recyclable Mg-Al-hydrotalcite-OtBu (HT-OtBu) by the interaction of KOtBu with the calcined hydrotalcite that transforms a well-defined stoichiometric WE reaction into a catalytic one in an effort to minimize the quantum of effluents released and reduce the cost of the process is described here. HT-OtBu is found to be an efficient solid base for WE reactions for the simple synthesis of α,β-unsaturated esters and nitriles for the first time. The HT-OtBu, composed of various ratios of Mg/Al (i.e., 2, 2.5, and 3) and different contents of tBuO - (Mg/Al:3), and their precursors were prepared and well characterized to draw a correlation between structure and reactivity of the hydrotalcites in WE reactions.
- Choudary, Boyapati M.,Kantam, Mannepalli L.,Reddy, Chinta Reddy V.,Bharathi, Balagam,Figueras, Francois
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p. 191 - 200
(2007/10/03)
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- Unexpected catalyst for Wittig-type and dehalogenation reactions
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A novel catalyst 2 for Wittig-type and dehalogenation reactions was developed. In the presence of triphenyl phosphite, a wide variety of aldehydes could react with α-bromoacetates to afford α,β-unsaturated esters or ketones in high yields with excellent E-stereoselectivity when 1-2 mol % of compound 2 was used. Compound 2 was also an effective catalyst for reductive dehalogenation of α-bromocarbonyl compounds. The mechanisms for the above reactions were also proposed.
- Huang, Zheng-Zheng,Tang, Yong
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p. 5320 - 5326
(2007/10/03)
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- Electrochemical vinylation of aryl and vinyl halides with acrylate esters catalyzed by cobalt bromide
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A consumable anode process permits the electrochemical Heck reaction between aromatic or vinylic halides and acrylate esters using cobalt bromide as catalyst associated with bipyridine as ligand in a mixture of acetonitrile/triethylamine/pyridine as solvent.
- Gomes, Paulo,Gosmini, Corinne,Nédélec, Jean-Yves,Périchon, Jacques
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p. 5901 - 5903
(2007/10/03)
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- P(RNCH2CH2)3N: An efficient promoter for the direct synthesis of E-α,β-unsaturated esters
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Upon reacting ethyl acetate or methyl propionate with a variety of aromatic aldehydes in the presence of 1.06-1.2 equiv. of the pro-azaphosphatranes, P(MeNCH2CH2)3N, P(i-PrNCH2CH2)3N or [P(i-PrNCH2CH2)2(NHCH2CH 2)N at 40-50°C for 2-6 h in isobutyronitrile, the corresponding α,β-unsaturated esters were formed as the only products. Ethyl acetate reacts with aldehydes to form exclusively E-isomers while the higher homologue methyl propionate gives rise to a mixture of E and Z isomers with the former as the major product. When used as the solvent, methyl propionate selectively forms the E-α,β-unsaturated ester. The reaction is not as successful for the preparation of α,β-unsaturated ketones.
- Kisanga, Philip,D'sa, Bosco,Verkade, John
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p. 8047 - 8052
(2007/10/03)
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- Novel Pd(II)- and Pt(II)-catalyzed regio- and stereoselective trans-hydroarylation of alkynes by simple arenes
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Efficient trans-hydroarylation of alkynes by simple arenes has been realized regio- and stereoselectively at room temperature in the presence of Pd(II) or Pt(II) catalysts and a mixed solvent containing trifluoroacetic acid (TFA). Various arenes undergo trans-hydroarylation selectively across terminal and internal C - C triple bonds - including those conjugated to CHO, COMe, CO2H, and CO2Et groups, affording kinetically controlled cis-arylalkenes predominantly in most cases, especially, in good yields for electron-rich arenes and activated alkynes. The formation of arene/alkyne 1/2 or 2/1 adducts as side products is dependent on the arenes' and alkynes' substituents, which can be suppressed in some cases by changing the catalyst, catalyst concentration, and reaction time. The Pt(II) system, PtCl2/2AgOAc/TFA, shows lower catalytic activity than Pd(OAc)2/TFA, but higher selectivity, giving higher yields of adducts at the same conversion. On the basis of several isotope experiments and control reactions, a possible mechanism involving electrophilic metalation of aromatic C - H bonds by in-situ-generated cationic Pd(II) and Pt(II) species leading to intermolecular trans-arylpalladation to alkyes has been discussed.
- Jia, Chengguo,Lu, Wenjun,Oyamada, Juzo,Kitamura, Tsugio,Matsuda, Kenji,Irie, Masahiro,Fujiwara, Yuzo
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p. 7252 - 7263
(2007/10/03)
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- Highly Efficient Pd-Catalyzed Coupling of Arenes with Olefins in the Presence of tert-Butyl Hydroperoxide as Oxidant
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(matrix presented) ArH : benznoid and non-benzenoid. R = H, CH3, Ph. R1 = Ph, CO2Et, COMe, CHO, CO2H, CN. The oxidative coupling of arenes with olefins has been performed efficiently in the presence of catalytic amounts of palladium acetate and benzoquinone (BQ) with tert-butyl hydroperoxide as the oxidant in up to 280 turnover numbers (TON). The catalytic system is especially active for the coupling of heterocycles such as furans and indole with activated olefins. The reaction is highly regio-and stereoselective, giving trans-olefins predominantly.
- Jia, Chengguo,Lu, Wenjun,Kitamura, Tsugio,Fujiwara, Yuzo
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p. 2097 - 2100
(2008/02/10)
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