- Photoinduced Regioselective Olefination of Arenes at Proximal and Distal Sites
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The Fujiwara-Moritani reaction has had a profound contribution in the emergence of contemporary C-H activation protocols. Despite the applicability of the traditional approach in different fields, the associated reactivity and regioselectivity issues had
- Ali, Wajid,Anjana, S. S.,Bhattacharya, Trisha,Chandrashekar, Hediyala B.,Goswami, Nupur,Guin, Srimanta,Maiti, Debabrata,Panda, Sanjib,Prakash, Gaurav,Saha, Argha,Sasmal, Sheuli,Sinha, Soumya Kumar
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supporting information
p. 1929 - 1940
(2022/02/01)
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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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- Metal-free domino Cloke-Wilson rearrangement-hydration-dimerization of cyclopropane carbaldehydes: A facile access to oxybis(2-aryltetrahydrofuran) derivatives
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In this work, we have demonstrated a metal-free transformation of cyclopropane carbaldehydes to oxybis(2-aryltetrahydrofuran) derivatives via a domino Cloke-Wilson rearrangement-hydration-dimerization sequence. Commercially inexpensive p-toluene sulfonic acid (PTSA) was used as a Br?nsted acid catalyst, and reactions were conducted in an open-flask. Detection of reaction intermediates were carried to get an insight into the reaction pathway.
- Banerjee, Prabal,Dey, Raghunath,Rajput, Shruti
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- Accessing dihydro-1,2-oxazine via cloke-wilson-type annulation of cyclopropyl carbonyls: application toward the diastereoselective synthesis of pyrrolo[1,2- b][1,2]oxazine
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A convenient additive-free synthesis of dihydro-4H-1,2-oxazines via a Cloke-Wilson-type ring expansion of the aryl-substituted cyclopropane carbaldehydes with the hydroxylamine salt is introduced. Comparatively less active cyclopropyl ketones also follow a similar protocol if supplemented by catalytic p-toluene sulfonic acid monohydrate. The transformation is performed in an open-to-air flask as it shows negligible sensitivity toward air/moisture. Dihydro-4H-1,2-oxazines when subjected to cycloaddition with the cyclopropane diester afford a trouble-free formulation of the valued hexahydro-2H-pyrrolo[1,2-b][1,2]oxazine derivatives. A cascade one-pot variant of this two-step strategy offers a comparable overall yield of the final product.
- Banerjee, Prabal,Kumar, Pankaj,Kumar, Rakesh
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supporting information
p. 6535 - 6550
(2020/06/09)
-
- Iron-Catalyzed Cross-Coupling of Bis-(aryl)manganese Nucleophiles with Alkenyl Halides: Optimization and mechanistic investigations
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Various substituted bis-(aryl)manganese species were prepared from aryl bromides by one-pot insertion of magnesium turnings in the presence of LiCl and in situ trans-metalation with MnCl2 in THF at ?5 ?C within 2 h. These bis-(aryl)manganese reagents undergo smooth iron-catalyzed cross-couplings using 10 mol% Fe(acac)3 with various functionalized alkenyl iodides and bromides in 1 h at 25 ?C. The aryl-alkenyl cross-coupling reaction mechanism was thoroughly investigated through paramagnetic 1H-NMR, which identified the key role of tris-coordinated ate-iron(II) species in the catalytic process.
- Rousseau, Lidie,Desaintjean, Alexandre,Knochel, Paul,Lefèvre, Guillaume
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supporting information
(2020/02/18)
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- Metal-Free Ring Opening Cyclization of Cyclopropane Carbaldehydes and N-Benzyl Anilines: An Eco-Friendly Access to Functionalized Benzo[b]azepine Derivatives
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Herein, we report a p-toluenesulfonic acid (PTSA) initiated mild and user-friendly ring opening/domino ring opening cyclization reaction (depends on substituent present in N-benzyl aniline) of cyclopropane carbaldehyde and N-benzyl aniline towards the formation of substituted 4-amino butanal/2,3-dihydro-1H-benzo[b]azepine. The product dihydro-1H-benzo[b]azepine was also converted into the corresponding tetrahydro-1H-benzo[b]azepine. (Figure presented.).
- Dey, Raghunath,Banerjee, Prabal
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supporting information
p. 2849 - 2854
(2019/04/26)
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- Design of novel monoamine oxidase-B inhibitors based on piperine scaffold: Structure-activity-toxicity, drug-likeness and efflux transport studies
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Piperine has been associated with neuroprotective effects and monoamine oxidase (MAO) inhibition, thus being an attractive scaffold to develop new antiparkinsonian agents. Accordingly, we prepared a small library of piperine derivatives and screened the inhibitory activities towards human MAO isoforms (hMAO-A and hMAO-B). Structure-activity relationship (SAR) studies pointed out that the combination of α-cyano and benzyl ester groups increased both potency and selectivity towards hMAO-B. Kinetic experiments with compounds 7, 10 and 15 indicated a competitive hMAO-B inhibition mechanism. Compounds 15 and 16, at 10 μM, caused a small but significant decrease in P-gp efflux activity in Caco-2 cells. Compound 15 stands out as the most potent piperine-based hMAO-B inhibitor (IC50 = 47.4 nM), displaying favourable drug-like properties and a broad safety window. Compound 15 is thus a suitable candidate for lead optimization and the development of multitarget-directed ligands.
- Borges, Fernanda,Chavarria, Daniel,Fernandes, Carlos,Gil-Martins, Eva,Oliveira, Paulo J.,Remi?o, Fernando,Silva, Catia,Silva, Renata,Silva, Tiago,Silva, Vera,Soares, Pedro
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- Modular synthesis and biological investigation of 5-hydroxymethyl dibenzyl butyrolactones and related lignans
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Dibenzyl butyrolactone lignans are well known for their excellent biological properties, particularly for their notable anti-proliferative activities. Herein we report a novel, efficient, convergent synthesis of dibenzyl butyrolactone lignans utilizing the acyl-Claisen rearrangement to stereoselectively prepare a key intermediate. The reported synthetic route enables the modification of these lignans to give rise to 5-hydroxymethyl derivatives of these lignans. The biological activities of these analogues were assessed, with derivatives showing an excellent cytotoxic profile which resulted in programmed cell death of Jurkat T-leukemia cells with less than 2% of the incubated cells entering a necrotic cell death pathway.
- Davidson, Samuel J.,Pilkington, Lisa I.,Dempsey-Hibbert, Nina C.,El-Mohtadi, Mohamed,Tang, Shiying,Wainwright, Thomas,Whitehead, Kathryn A.,Barker, David
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- Hydroamination versus Allylic Amination in Iridium-Catalyzed Reactions of Allylic Acetates with Amines: 1,3-Aminoalcohols via Ester-Directed Regioselectivity
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In the presence of a neutral dppf-modified iridium catalyst and Cs2CO3, linear allylic acetates react with primary amines to form products of hydroamination with complete 1,3-regioselectivity. The collective data, including deuterium labeling studies, corroborate a catalytic mechanism involving rapid, reversible acetate-directed aminoiridation with inner-sphere/outer-sphere crossover followed by turnover-limiting proto-demetalation mediated by amine.
- Kim, Seung Wook,Wurm, Thomas,Brito, Gilmar A.,Jung, Woo-Ok,Zbieg, Jason R.,Stivala, Craig E.,Krische, Michael J.
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supporting information
p. 9087 - 9090
(2018/08/03)
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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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- 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)
-
- Total synthesis of (-)-bicubebin A, B, (+)-bicubebin C and structural reassignment of (-)-cis-cubebin
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The first total synthesis of (-)-bicubebin A, and two previously unreported dilignans, (-)-bicubebin B and (+)-bicubebin C has been achieved through the dimerization of (-)-cubebin, confirming the structure and absolute stereochemistry of (-)-bicubebin A. Analysis of the data for (-)-bicubebin B showed it matched that of reported compound (-)-cis-cubebin. The NMR data of the subsequently synthesized proposed structure of cis-cubebin confirmed that its original proposed structure was incorrect.
- Davidson, Samuel J.,Pearce, A. Norrie,Copp, Brent R.,Barker, David
-
supporting information
p. 5368 - 5371
(2017/11/06)
-
- Silver-Catalyzed Cross-Olefination of Donor and Acceptor Diazo Compounds: Use of N-Nosylhydrazones as Diazo Surrogate
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The cross-olefination reaction of donor and acceptor diazo compounds was explored. The use of N-nosylhydrazones as diazo surrogates and the dependence on silver catalysis were crucial for the reaction development. A variety of (hetero)aryl N-nosylhydrazones and α-diazo esters, amides, and phosphonates were compatible, and the functionalized alkene products were afforded in good to high yields with moderate (Z)/(E) selectivities. The experimental and DFT calculation results suggest that the cross-selectivity is due to selective activation of the silver catalyst for donor diazo compounds.
- Liu, Zhaohong,Liu, Binbin,Zhao, Xue-Feng,Wu, Yan-Bo,Bi, Xihe
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supporting information
p. 928 - 932
(2017/02/15)
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- Solvent-free, one-pot synthesis of α,β-unsaturated esters in the presence of a C3-symmetric arsine
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An efficient synthesis of α, β-unsaturated esters is achieved via a one-pot reaction in the presence of a C3-symmetric arsine. The key advantages are the short reaction time, simple workup, mild reaction conditions, and high yields.
- Wang, Changqing,Yang, Liu,Zhou, Rong,Mei, Guangquan
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supporting information
p. 1074 - 1079
(2016/07/16)
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- Copper(I)-Catalyzed Allylic Substitutions with a Hydride Nucleophile
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An easily accessible copper(I)/N-heterocyclic carbene (NHC) complex enables a regioselective hydride transfer to allylic bromides, an allylic reduction. The resulting aryl- and alkyl-substituted branched α-olefins, which are valuable building blocks for synthesis, are obtained in good yields and regioselectivity. A commercially available silane, (TMSO)2Si(Me)H, is employed as hydride source. This protocol offers a unified alternative to the established metal-catalyzed allylic substitutions with carbon nucleophiles, as no adaption of the catalyst to the nature of the nucleophile is required.
- Nguyen, T. N. Thanh,Thiel, Niklas O.,Pape, Felix,Teichert, Johannes F.
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supporting information
p. 2455 - 2458
(2016/06/09)
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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)
-
- 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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- Biphilic organophosphorus catalysis: Regioselective reductive transposition of allylic bromides via PIII/PV redox cycling
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We report that a regioselective reductive transposition of primary allylic bromides is catalyzed by a biphilic organophosphorus (phosphetane) catalyst. Spectroscopic evidence supports the formation of a pentacoordinate (σ5-P) hydridophosphorane as a key reactive intermediate. Kinetics experiments and computational modeling are consistent with a unimolecular decomposition of the σ5-P hydridophosphorane via a concerted cyclic transition structure that delivers the observed allylic transposition and completes a novel PIII/PV redox catalytic cycle. These results broaden the growing repertoire of reactions catalyzed within the PIII/PV redox couple and suggest additional opportunities for organophosphorus catalysis in a biphilic mode.
- Reichl, Kyle D.,Dunn, Nicole L.,Fastuca, Nicholas J.,Radosevich, Alexander T.
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supporting information
p. 5292 - 5295
(2015/05/13)
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- Wittig Reactions of Trialkylphosphine-derived Ylides: New Directions and Applications in Organic Synthesis
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The development of semi-stabilized, stabilized, and functionalized ylides derived from short-chain trialkylphosphines in the Wittig-type olefination reactions toward the synthesis of alkenes, including stilbenes, styrenes, and 1,3-dienes, as well as reagents for homologation reactions, are described. The methods allow easy access to alkenes with high (E)-stereoselectivity in good yield. These reactions are conducted with weak bases in aqueous media, which allows easy separation of water-soluble phosphine oxides. The development of a mild organocatalytic process for the Wittig reaction and extension toward the preparation of reporter stilbenes under biological conditions are also described. Applications toward the preparation of biologically active natural products and derivatives are discussed.
- McNulty, James,McLeod, David,Das, Priyabrata,Zepeda-Velázquez, Carlos
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p. 619 - 632
(2016/01/15)
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- N,N,N′,N′-Tetramethylenediamine dioxide (TMEDAO2) facilitates atom economical/open atmosphere Ley-Griffith (TPAP) tandem oxidation-Wittig reactions
-
N,N,N′,N′-Tetramethylethylenediamine dioxide (TMEDAO2) was explored as a more atom economical co-oxidant for the Ley-Griffith oxidation of alcohols to aldehydes. TMEDAO2 was found to selectivity oxidise benzylic and allylic alcohols in comparable yields to that of the standard Ley-Griffith co-oxidant (NMO). Importantly TMEDAO2 facilitated tandem Ley-Griffith-Wittig reactions with stabilised ylides, in good to excellent yields, without the requirement of anhydrous conditions.
- Read, Christopher D. G.,Moore, Peter W.,Williams, Craig M.
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supporting information
p. 4537 - 4540
(2015/09/15)
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- NOVEL PIPERINE DERIVATIVES AND USES THEREOF
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The present invention provides novel piperine derivatives. The present pharmaceutical or food composition containing a piperine derivative as an active ingredient is very effective in preventing or treating metabolic diseases including obesity, diabetes, dyslipidemia, fatty liver and insulin resistance syndrome. Piperine derivatives of the present invention useful as pharmaceuticals compositions or functional food compositions has therapeutic efficacies for metabolic syndrome selected from the group consisting of obesity, diabetes, hyperlipidemia, fatty liver and insulin resistance syndrome, and also suppress the differentiation of progenitor cells and reduce the accumulation of triglycerides.
- -
-
Paragraph 0071; 0072
(2015/01/06)
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- Regioselective route for arylnaphthalene lactones: Convenient synthesis of taiwanin C, justicidin E, and daurinol
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Arylnaphthalene lactones are natural products which can be isolated from a wide range of plants and have the significant biological activities including cytotoxicity, antimicrobial, diuretic, and ion channel blocking. The drawback of the previous intramolecular Diels-Alder reaction of 3-arylprop-2-ynyl 3-arylpropiolates was to generate two regioisomers of arylnaphthalene lactone without selectivity. Herein, we report a convenient and regioselective synthesis method in which the intramolecular Diels-Alder reaction of an arylalkene-arylalkyne and subsequent DDQ oxidation was used for Type I and Type II arylnaphthalene lactones, respectively. We demonstrated the synthesis of three lignans, taiwanin C (Type I), justicidin E (Type II), and daurinol (Type I and anti-cancer activity).
- Park, Ju-Eun,Lee, Juyeun,Seo, Seung-Yong,Shin, Dongyun
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p. 818 - 820
(2014/02/14)
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- Silylative cyclopropanation of allyl phosphates with silylboronates
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A potassium-bis(trimethylsilyl)amide-mediated cyclopropanation of allyl phosphates with silylboronates has been developed. Unlike the reported copper-catalyzed allylic substitution reactions, the nucleophile selectively attacks at the β-position of the allylic substrates under the present reaction conditions. The mechanism of this process has also been investigated, thus indicating the involvement of a silylpotassium species as the active nucleophilic component.
- Shintani, Ryo,Fujie, Ryuhei,Takeda, Momotaro,Nozaki, Kyoko
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supporting information
p. 6546 - 6549
(2014/06/24)
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- OMS-2 for aerobic, catalytic, one-pot alcohol oxidation-wittig reactions: Efficient access to α,β-unsaturated esters
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Manganese oxide octahedral molecular sieve (OMS) materials with well-defined pores have been extensively studied over two decades due to their intriguing chemical and physical properties. OMS-2, the synthetic cryptomelane form of manganese oxide, was synthesized by a modified reflux method and was found to be highly active for obtaining α,β-unsaturated esters (up to 95 % yield and with high diastereoselectivities) from a variety of benzyl, heteroaryl, allyl and alkyl alcohols via one-pot alcohol oxidation-Wittig reaction. The transformation utilizes air as the stoichiometric oxidant, and the inexpensive catalyst can be recovered and reused. Filter and use again! Porous manganese oxide molecular sieve based catalysts were found to efficiently promote the oxidation of a variety of alcohols to the aldehydes, which reacted insitu with stabilized Wittig reagent, providing almost exclusively E-α,β-unsaturated esters in good to excellent yields. The heterogeneous catalyst used was made from inexpensive starting materials, and the recovered catalyst was found to be reusable with a modest loss in activity.
- Kona, Jagadeswara R.,King'Ondu, Cecil K.,Howell, Amy R.,Suib, Steven L.
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p. 749 - 752
(2014/03/21)
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- Synthesis and SAR investigation of natural phenylpropene-derived methoxylated cinnamaldehydes and their novel Schiff bases as potent antimicrobial and antioxidant agents
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A series of cinnamyl compounds were synthesized from abundantly available methoxylated phenylpropenes and evaluated for their antimicrobial activity by the broth microdilution method against fourteen opportunistic bacterial and fungal human pathogens. Structure-activity relationship studies indicated that methylenedioxy cinnamaldehyde exhibited promising broad-spectrum activity against the tested microorganisms and hence was used as a lead structure to synthesize novel Schiff bases/heterocyclic compounds (23-33) under microwave irradiation. Out of these, thiazole-based Schiff bases have shown promising antibacterial activity against B. subtilis (26; MIC 0.12 mM), M. luteus (27; MIC 0.20 mM), and S. aureus (27; MIC 0.20 mM). Also, the compounds 23-33 were investigated for in vitro antioxidant activity using DPPH? assay where compound 28 showed a maximum of 80.71 % inhibition.
- Sharma, Upendra K.,Sood, Swati,Sharma, Nandini,Rahi, Praveen,Kumar, Rakesh,Sinha, Arun K.,Gulati, Arvind
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p. 5129 - 5140
(2013/12/04)
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- A novel ketone olefination via organozinc reagents in the presence of diphenyl phosphite
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Carbonyl compounds react with organozinc reagents in the presence of diphenyl phosphite to give the corresponding olefins. A variety of 1,3-dienes and unsaturated esters were obtained in moderate to excellent yields under mild conditions. The Royal Society of Chemistry 2012.
- Cui, Hua,Li, Ying,Zhang, Songlin
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supporting information
p. 2862 - 2869
(2012/11/07)
-
- Synthesis of melicodenines C, D and e
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A synthesis of the unusual cyclobutane-quinolinone alkaloids melicodenines C, D and E by intermolecular [2+2] cycloaddition is described.
- Holla, Harish,Jenkins, Ian D.,Neve, Juliette E.,Pouwer, Rebecca H.,Pham, Ngoc,Teague, Simon J.,Quinn, Ronald J.
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supporting information
p. 7101 - 7103
(2013/01/15)
-
- Chemical plants: High-value molecules from essential oils
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As society faces a future of dwindling petrochemical supplies at increasing cost, much attention has been focused on methods to degrade biomass into renewable commodity-chemical building blocks. Reported here is a powerful complementary approach that amplifies the complexity of molecular structures present in plant materials. Essential-oil phenylpropenoids are transformed via acrylate cross-metathesis into potent antioxidants that are widely used in perfumery and cosmetics, and in treating disorders associated with oxidative damage.
- Lummiss, Justin A. M.,Oliveira, Kelley C.,Pranckevicius, Alexandre M. T.,Santos, Alexandra G.,Dos Santos, Eduardo N.,Fogg, Deryn E.
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supporting information
p. 18889 - 18891
(2013/01/15)
-
- Synthesis, characterization, antidepressant and antioxidant activity of novel piperamides bearing piperidine and piperazine analogues
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A series of piperamide derivatives (8a-j) was synthesized with various substituted piperidine and piperazine compounds. The prepared compounds were evaluated for antibacterial activity against gram-positive and gram-negative bacteria and antifungal activity by disc diffusion method. The antioxidant activity of the compounds was evaluated by DPPH and superoxide radical scavenging method and antidepressant activity using forced swim and tail suspension behavioral despair tests in mice. The compounds 8a, 8b and 8c were investigated for their monoamine oxidase A and B (MAO-A and MAO-B) inhibitory property. Some of the test compounds were active in forced swim test (FST) and tail suspension test (TST). Compounds 8a and 8b showed a significant effect, when compared to standard drug, clorgyline.
- Prashanth,Revanasiddappa, Hosakere D.,Lokanatha Rai,Veeresh
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supporting information
p. 7065 - 7070
(2013/01/15)
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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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- Amine- and sulfonamide-promoted wittig olefination reactions in water
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Amine-promoted olefination: The reaction of a phosphonium salt and an aldehyde in water to yield alkenes with high E-configurational control is promoted by catalytic amounts of non-basic amines in aqueous bicarbonate media (see scheme). Possible catalytic cycles involving imines and iminium intermediates are discussed.
- McNulty, James,McLeod, David
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supporting information; experimental part
p. 8794 - 8798
(2011/09/14)
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- Rasta resin-PPh3 and its use in chromatography-free wittig reactions
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Rasta resin-PPh3, a new heterogeneous polystyrene-based phosphine, has been synthesized and used in one-pot Wittig olefination reactions of aldehydes. In these reactions an excess of rasta resin-PPh3 was used for the in situ generation of the phosphorane reactant and allowed for isolation of a high yield of very pure alkene product after only filtration and solvent removal. The excellent results obtained in this study are attributed to the flexible nature of the rasta resin structure, which makes it less dependant upon swelling than other heterogeneous polystyrene materials previously used to support phosphine reagents in Wittig reactions. Georg Thieme Verlag Stuttgart.
- Leung, Peter Shu-Wai,Teng, Yan,Toy, Patrick H.
-
supporting information; experimental part
p. 1997 - 2001
(2010/10/02)
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- Chromatography-free wittig reactions using a bifunctional polymeric reagent
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The first example of a polystyrene bearing two distinct reagent groups has been prepared. This phosphine and amine functionalized material was used in one-pot Wittig reactions with an aldehyde and either an α-halo-ester, -ketone, or -amide. Due to the heterogeneous nature of the polymer, the desired alkene product of these reactions could be isolated in excellent yield in essentially pure form after only filtration and solvent removal.
- Leung, Peter Shu-Wai,Teng, Yan,Toy, Patrick H.
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supporting information; experimental part
p. 4996 - 4999
(2010/12/25)
-
- P(i-PrNCH2CH2)3N: Efficient catalyst for synthesizing β-hydroxyesters and α,β-unsaturated esters using α-trimethylsilylethylacetate (TMSEA)
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(Chemical Equation Presented) We present an efficient synthesis of β-hydroxyesters and R,β-unsaturated esters via activation of the silicon-carbon bond of α-trimethylsilylethylacetate using catalytic amounts of the commercially available P(i-PrNCH2CH2) 3N 1a. Selectivity for either of these two products can be achieved simply by altering the catalyst loading and reaction temperature to afford addition or stereoselective condensation. This method is mild and tolerates a wide array of functional groups.
- Wadhwa, Kuldeep,Verkade, John G.
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supporting information; experimental part
p. 4368 - 4371
(2009/09/06)
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- Ruthenium-catalyzed, one-pot alcohol oxidation-wittig reaction producing αβ unsaturated esters
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By a one-pot process, αβ-unsaturated esters were synthesized in high yield through the Ru-catalyzed oxidation of primary alcohols and the coupling of the resulting aldehydes and stabilized Wittig reagents. The ruthenium catalyst is composed of ruthenium nanoparticles embedded in aluminum oxyhydroxide and can be recovered simply by filtration or decantation. Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009.
- Lee, Eun Young,Kim, Youngkwon,Lee, Jae Sung,Park, Jaiwook
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experimental part
p. 2943 - 2946
(2009/10/11)
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- Diazo reagents in copper(I)-catalyzed olefination of aldehydes
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The olefination of aldehydes to synthesize unsaturated ketones, esters, amides and phosphonates using diazo reagents and triphenylphosphine in the presence of copper(I) iodide as catalyst, is described. Good to excellent E:Z selectivities as well as yields were obtained for a large variety of aliphatic, aromatic and heteroaromatic aldehydes. The reaction showed also an excellent functional group compatibility and aldehydes were selectively reacted in the presence of ketone, nitro, amine, ether, acetal, thioether and halide groups. The use of a cost-effective copper salt as a catalyst is advantageous compared to previously reported expensive transition metal complexes. The method was used in the total synthesis of the scutifoliamide A, a biologically active compound that exhibits antifungal activity.
- Lebel, Helene,Davi, Michael
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supporting information; experimental part
p. 2352 - 2358
(2009/10/02)
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- Ionic liquid promoted selective debromination of α-bromoketones under microwave irradiation
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The debromination of α-bromoketones with an easily accessible ionic liquid, 1-methyl-3-pentylimidazolium tetrafluoroborate, [pmIm]BF4 under microwave irradiation has been investigated. By controlling the reaction time gem-α-dibromoketones are selectively debrominated to either monobromo or debromoketones. The α-monobromo- and α-monoiodoketones are dehalogenated while the corresponding chloroketones remain inert. The activated vic-bromoacetates are converted to the corresponding (E)-alkenes by the same procedure. These reactions do not require any organic solvent, any metal or any conventional reducing agent. The ionic liquid works here as catalyst as well as reaction medium and is recycled without any appreciable loss of its catalytic efficiency.
- Ranu, Brindaban C.,Chattopadhyay, Kalicharan,Jana, Ranjan
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p. 155 - 159
(2007/10/03)
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- Stereoselective synthesis of (E)-α,β-unsaturated esters via carbene-catalyzed redox esterification
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Stereoselective, carbene-mediated redox esterification of alkynyl aldehydes provides mild and atom economical access to (E)-configurated, α,β-unsaturated carboxylic esters. The organocatalytic method relies on the generation of activated carboxylates via extended/conjugated umpolung in the presence of catalytic amounts of carbene precursor and base.
- Zeitler, Kirsten
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p. 637 - 640
(2007/10/03)
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- The dihydrofuran template approach to furofuran synthesis
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Flash vacuum pyrrolysis of vinyl epoxides provides cis-dihydrofuran carboxylic esters in good yields and diastereoselectivities, which, on base-promoted epimerisation afford the complementary trans series. The compounds provide a viable template for a Lewis acid promoted cyclisation to provide the 2,6-diaryl-3,7-dioxabicyclo[3.3.0]octane core found in the furofuran series of natural lignans. This strategy is stereodivergent and can be controlled to provide the exo-exo, exo-endo or endo-endo stereochemistries. The approach has been exemplified in syntheses of the sesamyl furofurans (±)-epiasarinin and (±)-asarinin. The Royal Society of Chemistry 2006.
- Aldous, David J.,Batsanov, Andrei S.,Yufit, Dmitrii S.,Dalenon, Anne J.,Dutton, William M.,Steel, Patrick G.
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p. 2912 - 2927
(2008/02/09)
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- Electroreductive radical cyclization of ethyl 2-bromo-3-allyloxy- and -3-(propargyloxy)propanoates catalyzed by (tetramethylcyclam)nickel(I) electrogenerated at carbon cathodes in dimethylformamide
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Reductive intramolecular cyclization of ethyl 2-bromo-3-(3′,4′- methylenedioxyphenyl)-3-(propargyloxy)propanoate (1) and ethyl 3-allyloxy-2-bromo-3-(3′,4′-dimethoxyphenyl)-propanoate (2) promoted by (1,4,8,11-tetramethyl-1,4,8,11-tetraazacyclotetradecane)nickel(I), [Ni(tmc)]+, electrogenerated at glassy-carbon cathodes in dimethylformamide containing tetraalkylammonium salts, has been investigated. Cyclic voltammograms for reduction of [Ni(tmc)]2+ in the presence of 1 and 2 reveal that [Ni(tmc)]+ catalytically reduces these two compounds at potentials significantly more positive than those required for direct reduction of the bromo esters. During controlled-potential electrolyses of solutions of [Ni(tmc)]2+ in the presence of 1 and 2, catalytic reduction of each substrate proceeds by one-electron cleavage of the carbon-bromine bond to form a radical intermediate that undergoes cyclization to afford, respectively, ethyl 2-(3′,4′-methylenedioxyphenyl)-4- methylenetetrahydrofuran-3-carboxylate (3) and ethyl 2-(3′,4′- dimethoxyphenyl)-4-methyltetrahydrofuran-3-carboxylate (6). A mechanistic Scheme is proposed to account for the formation of each major product. Wiley-VCH Verlag GmbH & Co. KGaA, 2005.
- Esteves, Ana P.,Goken, Danielle M.,Klein, Lee J.,Leite, Luis F. M.,Medeiros, Maria J.,Peters, Dennis G.
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p. 4852 - 4859
(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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- Stereoselective synthesis of naturally occurring unsaturated amide alkaloids by a modified Ramberg-Baecklund reaction
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A convenient and rapid approach for the synthesis of naturally occurring unsaturated amide alkaloids 1a-1n by the recently developed one-flask Ramberg-Baecklund reaction is described. The starting material was alcohol 3, which was transformed into thiolacetate 4 using the Mitsunobu reaction. In situ cleavage of acetyl moiety of 4, followed by alkylation of the resulting thiol with appropriate chloroacetamide 5, provided the sulfide 6. Oxidation of sulfide 6 gave the corresponding sulfone 2. Treatment of the sulfone 2 with the dibromodifluoromethane in the presence of alumina-supported potassium hydroxide in dichloromethane solution afforded unsaturated amide alkaloids 1a-1n. To the best of our knowledge, the synthesis of 1e and 1i was reported for the first time.
- Li, Yang,Zhang, Yu,Huang, Zhi,Cao, Xiaoping,Gao, Kun
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p. 622 - 630
(2007/10/03)
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- Dichloroindium hydride (Cl2InH): A convenient reagent for stereoselective reduction of vic-dibromides to (E)-alkenes
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Dichloroindium hydride (Cl2InH) generated in situ from the combination of a catalytic amount of indium(III) chloride and sodium borohydride in acetonitrile reduces activated vic-dibromides to the corresponding (E)-alkenes in excellent yields.
- Ranu, Brindaban C.,Das, Arijit,Hajra, Alakananda
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p. 1012 - 1014
(2007/10/03)
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- The asymmetric synthesis of β-aryl-α-hydroxy esters from β-aryl-α,β-dihydroxy esters
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α,β-Dihydroxy-β-aryl esters obtained via Sharpless asymmetric dihydroxylation (AD) of substituted cinnamate esters are reduced by sequential reaction with trimethyl orthoacetate and acetyl bromide followed by catalytic hydrogenolysis in methanol to give enantiomerically enriched β-aryl-α-hydroxy esters.
- Lawrence, Nicholas J,Brown, Stephen
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p. 613 - 619
(2007/10/03)
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- Poly(ethylene glycol) (PEG) as a Reusable Solvent Medium for Organic Synthesis. Application in the Heck Reaction
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(Matrix Presented) PEG has been used as a solvent medium for regioselective Heck reactions with easy recyclability of solvent and Pd catalyst for the first time.
- Chandrasekhar,Narsihmulu,Shameem Sultana,Ramakrishna Reddy
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p. 4399 - 4401
(2007/10/03)
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- Cycloisomerization of 1,6-enynes in organoaqueous medium: An efficient and eco-friendly access to furan derivatives. Synthesis of a key intermediate of podophyllotoxin
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The first cycloisomerization of enynes catalyzed by Pd(TPPTS)3 catalyst in aqueous medium to give functionalized furans is described. This new reaction has been applied to the synthesis of podophyllotoxin analog.
- Galland, Jean-Christophe,Dias, Sonia,Savignac, Monique,Genêt, Jean-Pierre
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p. 5137 - 5148
(2007/10/03)
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- Radical cyclisation based approach to lignans. Synthesis of 4-arylmethyldihydrofuran-2-ones
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Bromoacetalisation of the cinnamyl alcohols 7a-d, obtained from the corresponding benzaldehydes, generated the bromoacetals 10a-d. The 5-exo trig radical cyclisation of the bromoacetals 10a-d followed by one step hydrolysis-oxidation of the resulting cyclic acetals 11a-d furnished the title compounds 6a-d, respectively, well-established intermediates of a variety of lignans.
- Srikrishna,Danieldoss
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p. 2357 - 2364
(2007/10/03)
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- Organophosphorus chemistry 32. 1 The reaction of vanillin, ortho-vanillin and piperonal with stabilized methylenetriphenylphosphoranes (wittig reagents)
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Vanillin (1) and piperonal (3) reacted with ylidenetriphenylphosphoranes 4a-f in boiling toluene following the Wittig mechanism to give the ethylenes 5a-f and 7a-f. Similarly, ethylenes 8c-f were produced when ortho-vanillin (2) was allowed to react with 4c-f. The reaction of aldehyde (2) with the P-ylides 4a,b yielded the Wittig products 8a,b and 8-methoxycoumarin (10). Triphenylphosphine oxide (TPPO, 6) was isolated and identified in all cases. The mechanism for formation of 10 was discussed. Structural reasonings for all new compounds were based upon compatible elementary as well as spectroscopic (IR, 1H-NMR and MS) measurements.
- Hafez, Taghrid S.,Henary, Maged M.,Mahran, Mohamed Refat H.
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- A Stereoselective Synthesis of N-[7-(3′,4′-Methylenedioxyphenyl)-2E,6E-heptadienoyl]pyrrolidine (Sarmentosine). a New Alkamide isolated from Pipersarmentosum
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A convenient stereoselective synthesis of N-[7-(3′, 4′-methylenedloxyphenyl)-2E, 6E- heptadienoyl]pyrrolidine (1), an alkaloid Isolated from the genus piper, has been performed starting from piperonal, where the stereochemistry was fixed by utilising the modified Wittig reaction.
- Bari,Vig,Sattar,Sethi, Madhuresh K.,Sharma
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p. 520 - 522
(2007/10/03)
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- Palladium-catalyzed conversion of aldehydes to alkenes in the presence of tri-n-butylphosphine
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Palladium-catalyzed conversion of aldehydes to alkenes in the presence of tri-n-butylphosphine is described.
- Shen, Yanchang,Zhou, Yuefen
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p. 513 - 514
(2007/10/02)
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