- Novel one-pot approach to synthesis of indanones Through Sb(V)-catalyzed reaction of phenylalkynes with aldehydes
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Catalytic SbF5 and the use of EtOH as an additive efficiently converted a mixture of phenylalkynes and aldehydes to indanone compounds in one pot, and the reaction stereoselectively afforded the corresponding 2,3-disubstituted indanones as a single trans-isomer.
- Saito, Akio,Umakoshi, Masaharu,Yagyu, Naomi,Hanzawa, Yuji
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Read Online
- Scope and mechanism of the highly stereoselective metal-mediated domino aldol reactions of enolates with aldehydes
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A one-pot transformation, which involves the reaction of ketones with aldehydes in the presence of metal halides to furnish tetrahydro-2H-pyran-2,4-diols in a highly diastereoselective manner, is investigated thoroughly by experiments and computations. Th
- Cinar, M. Emin,Engelen, Bernward,Panth?fer, Martin,Deiseroth, Hans-J?rg,Schlirf, Jens,Schmittel, Michael
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- Palladium-Catalyzed Carbonylative Synthesis of α-Branched Enones from Aryl Iodides and Arylallenes
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In this communication, an interesting carbonylation protocol for the preparation of α-branched enones has been established. Starting from readily available aryl iodides and allenes, with formic acid as the CO source and reductant, moderate to good yields of the desired enones were isolated. Although it is a carbonylation methodology, the use of a CO source can avoid the manipulation of CO gas directly. Notably, this procedure also presents the first example on carbonylative synthesis of α-branched enones.
- Geng, Hui-Qing,Hou, Chen-Yang,Wang, Le-Cheng,Wu, Xiao-Feng
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Read Online
- Reactivity of β-stannylketones. Elimination vs. substitution
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In the present work we report the results obtained in the reaction of β-stannylketones (I) with t-BuONa in dimethylsulfoxide (DMSO) and acetonitrile (ACN) as solvents. The reaction mechanisms probably involved are proposed.
- Murray, Ana Paula,Chopa, Alicia B.
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Read Online
- Palladium-Catalyzed Synthesis of α-Methyl Ketones from Allylic Alcohols and Methanol
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One-pot synthesis of α-methyl ketones starting from 1,3-diaryl propenols or 1-aryl propenols and methanol as a C1 source is demonstrated. This one-pot isomerization-methylation is catalyzed by commercially available Pd(OAc)2 with H2O as the only by-product. Mechanistic studies and deuterium labelling experiments indicate the involvement of isomerization of allyl alcohol followed by methylation through a hydrogen-borrowing pathway in these isomerization-methylation reactions.
- Biswal, Priyabrata,Samser, Shaikh,Meher, Sushanta Kumar,Chandrasekhar, Vadapalli,Venkatasubbaiah, Krishnan
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supporting information
p. 413 - 419
(2021/11/01)
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- Manganese(I) catalyzed cross-coupling of secondary allylic alcohols and primary alcohols
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Cross-coupling of alcohols to value-added products by using sustainable catalytic reactions has gained attention in recent years. Isomerization of secondary allylic alcohol to the corresponding enolizable ketone is an atom economical and known transformation. Herein, a selective cross-coupling of secondary allylic alcohol and primary alcohol is reported to afford the corresponding α-alkenyl or alkylation products. These catalytic protocols proceed via acceptorless dehydrogenative coupling (ADC) or borrowing hydrogen (BH) strategies, which liberates water and/or hydrogen as the only byproducts. Highly abundant manganese-based pincer catalysts catalyze the reactions.
- Pandia, Biplab Keshari,Pattanaik, Sandip,Gunanathan, Chidambaram
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- Substituent-Controlled Divergent Cascade Cycloaddition Reactions of Chalcones and Arylalkynols: Access to Spiroketals and Oxa-Bridged Fused Heterocycles
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Herein, we report substituent-controlled divergent cascade cycloaddition reactions of chalcones and arylalkynols in the presence of PtI2. Depending on the substituent on the chalcone, either spiroketals or oxa-bridged fused heterocycles could be obtained in the ranges of 86–97% and 87–95% yields under identical reaction conditions. Control experiments were carried out to elucidate the origin of the high chemoselectivity. These provide a method for the synthesis of a diverse array of structurally complex oxygen-containing heterocycles. (Figure presented.).
- Chang, Weixing,Kong, Jingyang,Li, Jing,Liu, Lingyan,Wang, Hongkai,Zeng, Tianlong
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supporting information
p. 4024 - 4032
(2021/07/12)
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- Organic nitrite donor as well as preparation method and medical application thereof
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The invention relates to the field of medicinal chemistry, in particular to an organic nitrite donor compound(structures shown in a general formula I and a general formula II)containing a 1nitromethyl2phenylethylene skeleton, a preparation method of the o
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Paragraph 0071-0073
(2021/01/24)
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- Design, Synthesis, and Biological Evaluation of Organic Nitrite (NO 2-) Donors as Potential Anticerebral Ischemia Agents
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The treatment of ischemic stroke (IS) remains a big challenge in clinics, and it is urgently needed to develop novel, safe, and effective medicines against IS. Here, we report the design, synthesis, and biological evaluation of organic NO2- donors as potential agents for the treatment of IS. The representative compound 4a was able to slowly generate low concentrations of NO2- by reaction with a thiol-containing nucleophile, and the NO2- was selectively converted into NO under ischemic/hypoxia conditions to protect primary rat neurons from oxygen-glucose deprivation and recovery (OGD/R)-induced cytotoxicity by enhancing the Nrf2 signaling and activating the NO/cGMP/PKG pathway. Treatment with 4a at 2 h before or after ischemia mitigated the ischemia/reperfusion-induced brain injury in middle cerebral artery occlusion (MCAO) rats by producing NO and enhancing Nrf2 signaling. Furthermore, 4a significantly promoted endothelial cell proliferation and angiogenesis within the ischemic penumbra. Our findings suggest that this type of NO2- donors, like 4a, may be valuable to fight IS and other ischemic diseases.
- Wu, Jianbing,Yin, Wei,Huang, Zhangjian,Zhang, Yinqiu,Jia, Jian,Cheng, Huimin,Kang, Fenghua,Huang, Kai,Sun, Tao,Tian, Jide,Xu, Xiaojun,Zhang, Yihua
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p. 10919 - 10933
(2021/08/16)
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- Chemoselective reduction of ?,¢-unsaturated carbonyl and carboxylic compounds by hydrogen iodide
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The selective reduction of ?,¢-unsaturated carbonyl compounds was achieved to produce saturated carbonyl compounds with aqueous HI solution. The introduction of an aryl group at an ? or ¢ position efficiently facilitated the reduction with good yield. The reaction was applicable to compounds bearing carboxylic acids and halogen atoms. Through the investigation of the reaction mechanism, it was found that Michael-type addition of iodide occurred to produce ¢-iodo compounds followed by the reduction of C-I bond via anionic and radical paths.
- Matsumoto, Shoji,Marumoto, Hayato,Akazome, Motohiro,Otani, Yasuhiko,Kaiho, Tatsuo
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p. 590 - 599
(2021/03/29)
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- Highly Enantioselective Iridium-Catalyzed Hydrogenation of Conjugated Trisubstituted Enones
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Asymmetric hydrogenation of conjugated enones is one of the most efficient and straightforward methods to prepare optically active ketones. In this study, chiral bidentate Ir-N,P complexes were utilized to access these scaffolds for ketones bearing the stereogenic center at both the α- and β-positions. Excellent enantiomeric excesses, of up to 99%, were obtained, accompanied with good to high isolated yields. Challenging dialkyl substituted substrates, which are difficult to hydrogenate with satisfactory chiral induction, were hydrogenated in a highly enantioselective fashion.
- Peters, Bram B. C.,Jongcharoenkamol, Jira,Krajangsri, Suppachai,Andersson, Pher G.
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p. 242 - 246
(2021/01/13)
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- New photochromic α-methylchalcones are highly photostable, even under singlet oxygen conditions: Breaking the α-methyl michael-system reactivity by reversible peroxybiradical formation
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The α-methylated chalcones 7a–7e behave as P-type photochromic substances with photo-stationary states (PSS) as high as 15:85 when irradiated at 350 nm. These compounds are easily accessible in pure E-configuration by aldol condensation or by oxidative co
- ?ngel, Banu,Brüllingen, Eric,Griesbeck, Axel G.,Renner, Melissa
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- N-para-sulfonium salt substituted pyrazoline derivative, photocurable composition and preparation method
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The invention relates to an N-para-sulfonium salt substituted pyrazoline derivative shown as the following formula (I) in the specification, a photocurable composition, and a preparation method of theN-para-sulfonium salt substituted pyrazoline derivative shown as the following formula (I). The N-para-sulfonium salt substituted pyrazoline derivative shown as formula (I) has good absorption at a wavelength of 350nm or above, and compared with a 5-substituted sulfonium salt, the N-para-sulfonium salt substituted pyrazoline derivative has the advantages of simpler and more convenient molecule synthesis steps and reduced cost of raw materials, and is more suitable for industrial production and application.
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Paragraph 0239-0241; 0245-0246
(2020/07/21)
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- Photoredox β-thiol-α-carbonylation of enones accompanied by unexpected Csp2-C(CO) bond cleavage
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An olefinic difunctionalization method of enones was presented hereviaaerobic visible-light catalysis. A novel reactivity was showcased in conjunction with the selective Csp2-C(CO) bond activation of enones, which provided a convenient method for the preparation of various β-thiolated-α-functionalized compounds. Moreover, the preliminary investigation of the mechanism indicated that a β-peroxysulfide intermediate was formed under the promotion of visible light under an oxygen atmosphere, which finally induced the unexpected C-C bond cleavage.
- Du, Ding,Feng, Jie,Ma, Rui,Zhang, Beichen,Zhang, Kuili
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supporting information
p. 7549 - 7553
(2020/10/13)
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- H-*BEA Zeolite-Catalyzed Nucleophilic Substitution in Allyl Alcohols Using Sulfonamides, Amides, and Anilines
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Herein, we report a novel zeolite-catalyzed nucleophilic substitution in allyl alcohols. The product yield was improved upon the addition of NaOTf (0.05 mol-percent) using the studied zeolites. The highest yields were observed using H-*BEA(Si/Al2 = 40)/NaOTf. The scope of the reaction with respect to the nucleophile was examined using 1,3-diphenylprop-2-ene-1-ol as a model substrate under optimized reaction conditions. p-Substituted aryl sulfonamides bearing electron-rich or electron-deficient substituents, alkyl sulfonamides, and heteroaryl sulfonamides undergo the amidation reaction to produce their corresponding allyl sulfonamides in good yield. Amides and anilines exhibited low activity under the optimized conditions, however, performing the reaction at 90 °C produced the target product. The scope of the allyl alcohol was investigated using p-toluenesulfonamide as the nucleophile and the reaction proceeded with a variety of allylic alcohols. To probe the practical utility of the H-*BEA-catalyzed amidation reaction, a gram-scale reaction was performed using 1.01 g (4.8 mmol) of allyl alcohol, which afforded the target product in 88 percent yield.
- Aoki, Shunsuke,Fujii, Takeshi,Morita, Sachiko,Nishida, Ryo,Ohtsuki, Akimichi,Okumura, Kazu
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- Proton-Coupled Electron Transfer: Transition-Metal-Free Selective Reduction of Chalcones and Alkynes Using Xanthate/Formic Acid
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Highly chemoselective reduction of α,β-unsaturated ketones to saturated ketones and stereoselective reduction of alkynes to (E)-alkenes has been developed under a transition-metal-free condition using a xanthate/formic acid mixture through proton-coupled electron transfer (PCET). Mechanistic experiments and DFT calculations support the possibility of a concerted proton electron-transfer (CPET) pathway. This Birch-type reduction demonstrates that a small nucleophilic organic molecule can be used as a single electron-transfer (SET) reducing agent with a proper proton source.
- Prasanna, Ramanathan,Guha, Somraj,Sekar, Govindasamy
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supporting information
p. 2650 - 2653
(2019/04/17)
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- Iron-Catalyzed Tandem Three-Component Alkylation: Access to α-Methylated Substituted Ketones
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The borrowing hydrogen strategy has been applied in the synthesis of α-branched methylated ketones via a tandem three-component reaction catalyzed by a diaminocyclopentadienone iron tricarbonyl complex. Various alkyl and aromatic methyl ketones underwent dialkylation with various primary alcohols and methanol as alkylating agents in mild reaction conditions and good yields. Deuterium labeling experiments suggested that the benzylic alcohol was the hydrogen source in this tandem process.
- Bettoni, Léo,Seck, Charlotte,Mbaye, Mbaye DIagne,Gaillard, Sylvain,Renaud, Jean-Luc
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supporting information
p. 3057 - 3061
(2019/05/10)
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- Stereodivergent Access to Enantioenriched Epoxy Alcohols with Three Stereogenic Centers via Ruthenium-Catalyzed Transfer Hydrogenation
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The resolution technique of stereodivergent reaction on racemic mixtures (stereodivergent RRM) was employed for the first time in ruthenium complex catalyzed transfer hydrogenation of racemic epoxy ketones, providing a new and very simple method that allows access to enantioenriched epoxy alcohols with three stereogenic centers in a one-step fashion. The protocol features simple reaction conditions, practical operation, ability to scale up, and broad group tolerance.
- Zhao, Zhifei,Bagdi, Prasanta Ray,Yang, Shuang,Liu, Jinggong,Xu, Weici,Fang, Xinqiang
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supporting information
p. 5491 - 5494
(2019/08/01)
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- Pd-catalyzed synthesis of α,β-unsaturated ketones by carbonylation of vinyl triflates and nonaflates
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A general and highly chemoselective Pd-catalyzed protocol for the synthesis of α,β-unsaturated ketones by carbonylation of vinyl triflates and nonaflates is presented. Applying the specific monophosphine ligand cataCXium A, the synthesis of various vinyl ketones as well as carbonylated natural product derivatives proceeds in good yields.
- Zhang, Shaoke,Neumann, Helfried,Beller, Matthias
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supporting information
p. 5938 - 5941
(2019/05/27)
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- Chalcone and cinnamate synthesis via one-pot enol silane formation-Mukaiyama aldol reactions of ketones and acetate esters
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Aryl alkyl ketones, acetate esters, and acetamides undergo facile one-pot enol silane formation, Mukaiyama aldol addition, and dehydrosilyloxylation in the presence of an amine base and excess trimethylsilyl trifluoromethanesulfonate. The chalcone and cinnamate products are generally recovered in high yield. The relative stoichiometry of the trimethylsilyl trifluoromethanesulfonate and amine base reagents determines whether the reaction yields the β-silyloxy carbonyl product or the α,β-unsaturated carbonyl.
- Downey, C. Wade,Glist, Hadleigh M.,Takashima, Anna,Bottum, Samuel R.,Dixon, Grant J.
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supporting information
p. 3080 - 3083
(2018/07/06)
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- Nickel-Catalyzed Hydrogen-Borrowing Strategy for α-Alkylation of Ketones with Alcohols: A New Route to Branched gem-Bis(alkyl) Ketones
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The α-alkylation of ketones using an earth-abundant and nonprecious NiBr2/L1 system is reported. This nickel-catalyzed reaction could be performed in gram scale and successfully applied in the synthesis of donepezil (Alzheimer's drug) and functionalization of steroid hormones and fatty acid derivatives. Synthesis of N-heterocycles, methylation of ketones, and one-pot double alkylation to bis-hetero aryl ketones using two different alcohols with a single catalyst broadens the scope of the catalytic protocol. Preliminary mechanistic studies using defined Ni-H species and deuterium-labeling experiments established the participation of the borrowing-hydrogen strategy.
- Das, Jagadish,Singh, Khushboo,Vellakkaran, Mari,Banerjee, Debasis
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supporting information
p. 5587 - 5591
(2018/09/25)
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- Synthesis and biological evaluation of α-methyl-chalcone for anti-cervical cancer activity
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A series of 31 chalcones were synthesized and evaluated for anti-proliferative activity against the human cervical cancer cell lines (HeLa and SiHa). Compound 19, (E)-1-(2,4-dihydroxyphenyl)-3-(4-(dimethylamino) phenyl)-2-methylprop-2-en-1-one was found to be an effective anti-proliferative agent in HeLa and SiHa cells (IC50 = 0.035 μM). Compound 19 increased the percentage of apoptosis in a dose-dependent manner, as measured by Annexin V-FITC (fluorescein isothiocyanate)/(propidium iodide) PI staining. Molecular modeling studies of compound 19 showed that the most potent structure was docked at the yeast 20 S proteasome binding site (Protein Data Bank code-3E47) and was stabilized in the cavity by various hydrophobic and hydrogen bonding interactions.
- Ren, Bing-zhao,Ablise, Mourboul,Yang, Xu-chao,Liao, Bo-er,Yang, Zheng
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p. 1871 - 1883
(2017/08/03)
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- CBr4 as a Halogen Bond Donor Catalyst for the Selective Activation of Benzaldehydes to Synthesize α,β-Unsaturated Ketones
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CBr4 has been employed as a halogen bond donor catalyst for the selective activation of aldehyde, to achieve an efficient solvent- and metal-free CC bond forming reaction in the presence of strong acid sensitive groups such as methoxy, cyanide, ester, and ketal for the synthesis of α,β-unsaturated ketones. This unique capability of CBr4 to act as a halogen bond donor has been explored and established using UV-vis as well as IR spectroscopy. Moreover, this unprecedented methodology enables the synthesis of the pharmaceutically important molecule licochalcone A.
- Kazi, Imran,Guha, Somraj,Sekar, Govindasamy
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supporting information
p. 1244 - 1247
(2017/03/14)
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- Barluenga's reagent with HBF4 as an efficient catalyst for alkyne-carbonyl metathesis of unactivated alkynes
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Barluenga's reagent (IPy2BF4, Py = pyridine) treated with HBF4 efficiently catalyzes the inter- and intramolecular alkyne-carbonyl metathesis of unactivated alkynes with aldehydes or ketones, most of which proceed at room temperature. This work represents the first catalytic application of the Barluenga's reagent.
- Murai, Kosuke,Tateishi, Keiichiro,Saito, Akio
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supporting information
p. 10352 - 10356
(2016/11/18)
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- Synthesis of α,β-unsaturated ketones from alkynes and aldehydes over Hβ zeolite under solvent-free conditions
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A facile Hβ zeolite-catalyzed strategy has been successfully developed for the synthesis of α,β-unsaturated ketones from alkynes and aldehydes under solvent-free conditions. The reaction proceeds via tandem hydration/condensation of alkynes with aldehydes to afford a range of α,β-unsaturated carbonyls in good to excellent yields. This journal is.
- Mameda, Naresh,Peraka, Swamy,Kodumuri, Srujana,Chevella, Durgaiah,Banothu, Rammurthy,Amrutham, Vasu,Nama, Narender
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p. 58137 - 58141
(2016/07/07)
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- Regioselective synthesis of enones via a titanium-promoted coupling of unsymmetrical alkynes with Weinreb amides
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A modular titanium-promoted coupling of unsymmetrical internal alkynes with Weinreb amides is described. The coupling reaction takes place at room temperature and affords E-trisubstituted enones in moderate to good yields with high levels of regioselectivity. The system shows moderate chemoselectivity.
- Silwal, Sajan,Rahaim, Ronald J.
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p. 8469 - 8476
(2015/03/18)
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- Dehydrogenation and oxidative coupling of alcohol and amines catalyzed by organosilicon-supported TiO2@PMHSIPN
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The catalytic dehydrogenation and tandem transformation of aromatic alcohols, including oxidative coupling of alcohols and amines, were achieved successfully using a catalytic amount of organosilicon-supported titania (TiO2@PMHSIPN), which enables the efficient synthesis of aromatic aldehydes, imines, and benzimidazoles in good to excellent yields. This journal is the Partner Organisations 2014.
- Wang, Hu,Zhang, Jin,Cui, Yu-Ming,Yang, Ke-Fang,Zheng, Zhan-Jiang,Xu, Li-Wen
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p. 34681 - 34686
(2014/11/08)
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- Tin(II) chloride mediated coupling reactions between alkynes and aldehydes
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Tin(II) chloride, which is insensitive to water and air, mediated the coupling reaction between alkynes and aldehydes as a Lewis acid in nitromethane to produce (E)-α,β-unsaturated ketones by a skeletal transformation in which one alkynic carbon atom changed into an oxo carbon atom accompanied by the cleavage of a C=O bond in the starting aldehydes. This coupling reaction was promoted by a catalytic amount of a primary or secondary alkanol. The coupling reaction between 1-deuterio-2-phenylethyne and benzaldehyde with BuOH afforded 1,3-diphenyl-2-deuterio-2-propenone (2-deuteriation: 94 % D), whereas the coupling reaction between phenylethyne and benzaldehyde with BuOD afforded 1,3-diphenyl-2-propenone (2-deuteriation: 0 % D). Because almost no exchange between hydrogen and deuterium at the 2-position of 1,3-diphenyl-2-propenone occurs in either of the reactions, the coupling reaction between alkynes and aldehydes with tin(II) chloride is presumed to proceed by nucleophilic addition of alkynes to aldehydes. The cleavage of the C-O single bond generated by the nucleophilic addition might be induced by the strong oxophilicity of tin. Coupling reactions occur between alkynes and aldehydes mediated by tin(II) chloride as a Lewis acid to produce (E)-α,β-unsaturated ketones by a skeletal transformation in which an alkynic carbon atom changes into an oxo carbon atom accompanied by cleavage of the C=O bond in the starting aldehydes. This coupling reaction is promoted by a catalytic amount of a primary or secondary alkanol. Copyright
- Masuyama, Yoshiro,Takamura, Wataru,Suzuki, Noriyuki
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p. 8033 - 8038
(2014/01/06)
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- Practical metal-free synthesis of chalcone derivatives via a tandem cross-dehydrogenative-coupling/elimination reaction
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Metal-free synthesis of chalcone derivatives through a tandem cross-dehydrogenative-coupling/elimination reaction is described. A simple and inexpensive ammonium persulfate salt enables the reaction between ketones and benzylamines to proceed with high stereoselectivity and good functional group compatibility.
- Wei, Yu,Tang, Jinghua,Cong, Xuefeng,Zeng, Xiaoming
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supporting information
p. 3165 - 3169
(2013/11/06)
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- InCl3/Me3SiCl-catalyzed direct michael addition of enol acetates to α,β-unsaturated ketones
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The direct Michael addition of enol acetates to α,β-unsaturated ketones was achieved using a combination of Lewis acid catalysts, InCl 3 and Me3SiCl, which furnished stable enol-form products that could be further transformed into functionalized 1,5-diketones by reactions with various electrophiles.
- Onishi, Yoshiharu,Yoneda, Yuki,Nishimoto, Yoshihiro,Yasuda, Makoto,Baba, Akio
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supporting information
p. 5788 - 5791
(2013/01/15)
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- Synthesis of tri- and tetrasubstituted pyrazoles via Ru(II) catalysis: Intramolecular aerobic oxidative C-N coupling
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An unprecedented ruthenium(II)-catalyzed intramolecular oxidative C-N coupling method has been developed for the facile synthesis of a variety of synthetically challenging tri- and tetrasubstituted pyrazoles. Dioxygen gas is employed as the oxidant in this transformation. The reaction demonstrates excellent reactivity, functional group tolerance, and high yields.
- Hu, Jiantao,Chen, Shi,Sun, Yonghui,Yang, Jing,Rao, Yu
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supporting information
p. 5030 - 5033,4
(2012/12/12)
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- Iron(III)-catalyzed cyclization of alkynyl aldehyde acetals: Experimental and computational studies
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FeCl3·6H2O-and FeBr3-catalyzed Prins cyclization/halogenation of alkynyl aldehyde acetals has been realized with acetyl chloride or bromide as halogen source in dichloromethane to afford 2-(1-halobenzylidene or alkylidene)
- Xu, Tongyu,Yang, Qin,Li, Dongpo,Dong, Jinhua,Yu, Zhengkun,Li, Yuxue
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supporting information; experimental part
p. 9264 - 9272
(2010/10/03)
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- Indium(III)-catalyzed coupling between alkynes and aldehydes to α,β-unsaturated ketones
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The combined use of a catalytic amount of InX3 (X = OTf and NTf2) and 1-butanol was found to be effective in formal alkynealdehyde metathesis. With this catalytic system, aromatic alkynes reacted with aromatic aldehydes to give chalcones in moderate to good yields. Alkynals were efficiently converted into 5- to 7-membered cyclic compounds by intramolecular alkyne-aldehyde coupling.
- Miura, Katsukiyo,Yamamoto, Kiyomi,Yamanobe, Aya,Ito, Keisuke,Kinoshita, Hidenori,Ichikawa, Junji,Hosomi, Akira
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supporting information; experimental part
p. 766 - 767
(2011/01/09)
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- Rhodium catalyzed reaction of internal alkynes with organoborons under CO atmosphere: a product tunable reaction
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Alkynes react with organoborons under a CO atmosphere in the presence of a rhodium(I) catalyst to afford mainly 5-aryl-2(5H)-furanones, α,β-unsaturated ketones, and indanones. The product selectivity can be tuned by modifying the reaction conditions.
- Artok, Levent,Ku?, Melih,Aksin-Artok, ?zge,Dege, Fatma Nurcan,?zkilin?, Fatma Yelda
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scheme or table
p. 9125 - 9133
(2010/01/16)
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- Highly enantioselective synthesis of optically active ketones by iridium-catalyzed asymmetric hydrogenation
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(Chemical Equation Presented) Close to perfect enantioselectivity (up to 99% ee, see scheme) is found for the formation of α-substituted ketones by the asymmetric hydrogenation of enones with an iridium-phosphinooxazoline catalyst. In an operationally simple process, both linear and cyclic substrates react well and afford the desired products in high yields. A wide variety of substituents are tolerated, thus making the method synthetically appealing.
- Lu, Sheng-Mei,Bolm, Carsten
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supporting information; experimental part
p. 8920 - 8923
(2009/05/30)
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- Synthesis of dihalohydrins and tri- and tetra-substituted olefins
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A novel synthesis reaction for highly stereospecific tri- and tetra-substituted olefins is described. A single stereoisomer of stable α-halo-α,β-ester is produced in high yield by the reaction of aldehyde or ketone with a trihalogenated compound such as t
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- Ytterbium triflate promoted coupling reaction between aryl alkynes and aldehydes
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A simple and efficient solvent-free coupling reaction affording regioselectively trans-α,β-enones from aryl alkynes and aldehydes catalysed by Yb(OTf)3 hydrate is described.
- Curini, Massimo,Epifano, Francesco,Maltese, Federica,Rosati, Ornelio
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p. 552 - 554
(2007/10/03)
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- Aldolases as leitmotiv - A nonenzymatic domino aldol reaction triggered by zinc bisenolate and polyenolate (ate) complexes
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A new zinc(II) mediated sequential aldol reaction is described for the diastereoselective one-pot synthesis of tetrahydropyran-2,4-diols. The dependence of the yield on the ratio Zn2+/enolate proposes that zinc(II) polyenolate and ate complexes may be involved.
- Schmittel,Ghorai
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p. 1992 - 1994
(2007/10/03)
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- Tandem addition β-lithiation - Alkylation sequence on α,β-unsaturated aldehydes
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A tandem reaction between (E)-cinnamaldehyde, 1a, and phenyllithium affording β-substituted dihydrochalcones was recently reported. NMR spectroscopic studies on the reaction mixture, as well as isotopic exchange reactions and trapping of two intermediates, provide clues on the several mechanistic steps of this new reaction. Extended studies revealed that β-alkyl-substituted α,β-unsaturated aldehydes and aliphatic lithium reagents did not afford good yields of the tandem reaction products, while aromatic lithium reagents gave good results. The aggregation features of the aryllithium reagents and the extended charged delocalization effects are considered to promote β-selectivity. This approach provides a convenient route for the synthesis of a wide variety of β-alkyl-substituted dihydrochalcones.
- Nudelman,Garcia
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p. 1387 - 1394
(2007/10/03)
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- Reactions of Carbanions Generated from 2-(Dialkylamino)-2-phenylacetonitriles with Disubstituted Acetylenes
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Reactions of aminonitriles 1a-e with disubstituted acetylenes 2, 3, carried out in DMSO in the presence of powdered sodium hydroxide and benzyltriethylammonium chloride (TEBAC) as a catalyst, afford either 4 and 5 or a mixture of 4 and 6; unmasking of the
- Zdrojewski, Tadeusz,Jonczyk, Andrzej
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p. 375 - 378
(2007/10/02)
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- New synthetic applications of organotin compounds: Synthesis of stereodefined 2-iodo-2-alkenones, 2-substituted (E)-2-alkenones and 2-methyl-2-cycloalkenones
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Stereoisomeric mixtures of 3-iodo-3-nonen-2-one, 8a, 2-iodo-1-phenyl-2-octen-1-one, 8b, 2-iodo-1,3-diphenyl-2-propen-1-one, 8c, as well as (Z)-3-iodo-4-phenyl-3-buten-2-one, 8d, have been efficiently synthesized by a reaction sequence involving a Pd-catalyzed reaction between the corresponding 1-alkynyl ketones, 10, and Bu3SnH followed by iododestannylation. Stereomutation experiments carried out in the presence of daylight and using catalytic amounts of I2 showed that the Z stereoisomers of 8a, 8b and 8c, which could be separated by MPLC on silica gel from the corresponding E stereoisomers, as well as compound (Z)-8d were more stable than their E stereoisomers. Compounds 8a-d underwent Pd-catalyzed cross-coupling reactions with C6H5SnMe3, CH2=CH-SnBu3 and SnMe4 providing an efficient route to the corresponding 2-substituted 2-alkenones, 13. However, the Pd-catalyzed reaction between (Z)-8c and PhSnMe3 afforded a mixture of the expected cross-coupled product, (E)-13f with the compound derived from methyl transfer, (E)-13e. The couplings involving (Z)-8a, (Z)-8b, (Z)-8c and (Z)-8d proceeded with clean retention of stereochemistry, but the Pd-catalyzed reaction between (E)-8c and SnMe4 afforded a stereoisomeric mixture of 13e. On the contrary, the coupling between (E)/(Z)-8b and SnMe4 produced stereoisomerically pure (E)-13c. Two 2-iodo-2-cycloalkenones, i.e. compounds 18a and 18b, also reacted with SnMe4, in the presence of a Pd catalyst, to give the corresponding 2-methyl-2-cycloalkenones, 19a and 19b, respectively, in satisfactory yields. Compound 19b represents a very useful precursor to methylenomycin B, 9.
- Bellina, Fabio,Carpita, Adriano,Ciucci, Donatella,De Santis, Massimo,Rossi, Renzo
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p. 4677 - 4698
(2007/10/02)
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- SYNTHESIS OF INDENES FROM PHENYLPROPANONES USING ALUMINA CATALYST
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1,3-Diphenylpropan-2-one undergoes dehydration over alumina at around 400 deg C to form 1,3-diphenylallene which cyclizes to 2-phenylindene.Since the parent ketone can be obtained under the reaction conditions from phenylacetic acid, the present reaction forms a one step syntheses of 2-phenylindene from phenylacetic acid. 3- and 4-methylphenylacetic acids also give the corresponding indenes. 1,3-Diphenylpropan-1-ones also give phenylindenes, presumably by a direct cyclodehydration reaction.
- Jayamani, M.,Pant, Nalin,Ananthan, S.,Narayanan, K.,Pillai, C. N.
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p. 4325 - 4332
(2007/10/02)
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- Synthesis of Selenacoumarins
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Selenacoumarin (2a) and 3-methylselenacoumarin (2b) have been synthesized by the cyclisation of selenophenyl cinnamate (1a) and selenophenyl 2-methylcinnamate (1b) respectively in the presence of AlCl3 in chlorobenzene.The compounds have been characterised by elemental analysis and spectral (IR, PMR and mass) data.
- Jayachandran, T.,Manimaran, T.,Ramakrishnan, V. T.
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p. 328 - 330
(2007/10/02)
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- Structure and Stereochemistry of the Dehydrobromination of some β-Bromo Ketones Derived from Alkyl Phenyl Ketones and Benzaldehyde
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The aldol reaction of alkyl phenyl ketones with benzaldehyde in the presence of hydrogen bromide affords diastereomeric β-bromo ketones under thermodynamic control.Thus, from propiophenone (8a) two diastereomeres 9a are obtained in a 67 : 33 ratio, while
- Quast, Helmut,Mueller, Bodo,Peters, Karl,Schnering, Hans Georg von
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p. 1525 - 1546
(2007/10/02)
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- PREPARATION OF 1-PHENYL-3-METHYLISOQUINOLINE AND ITS DERIVATIVES FROM OXIMES OF 3-ARYL-2-METHYL-1-PHENYL-2-PROPEN-1-ONES
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1-Phenyl-3-methylisoquinoline and its derivatives substituted in 5, 6 or 7 positions (4) have been obtained by cyclization reaction of N-α-methylstyrylbenzimidoyl chloride (3) produced by Beckmann rearrangement by appopriate oximes (2) in the presence of PCl5.
- Zielinski, Wojciech
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p. 2209 - 2215
(2007/10/02)
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- BECKMANN REARRANGEMENT OF α-SUBSTITUTED β-ARYL-α,β-UNSATURATED KETOXIMES IN PRESENCE OF PCl5
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The behavior of α-methylbenzylideneacetone and α-methylbenzylideneacetophenone oximes in presence of PCl5 under the Beckmann rearrangement conditions has been investigated.The possible formation of N-acyl-1-methyl-2-phenylvinylamines and other products, such as benzyl methyl ketone, unsubstituted amides or nitriles has been discussed.
- Zielinski, Wojciech
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p. 745 - 754
(2007/10/02)
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- Catalytic dehydrogenation process for the preparation of 3,4,5-trisubstituted pyrazoles
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There is provided a process for the preparation of 3,5-disubstituted pyrazoles which involves: A. the reaction of a methyl ketone, such as acetophenone or an appropriate derivative thereof, with an appropriate aldehyde, such as benzaldehyde in the presence of base to form a 1,3-disubstituted α,β-unsaturated ketone, such as chalcone or a substituted chalcone, B. the acidification of said α,β-unsaturated ketone, followed by treatment of the acidified reaction mixture with hydrazine to form a disubstituted pyrazoline, and C. the catalytic dehydrogenation of said pyrazoline to yield the desired 3,5-disubstituted pyrazole.
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