- Synthesis of vinylic sulfones in aqueous media
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A green method for the sulfination of allenic carbonyl compounds to access a wide variety of vinylic sulfones is developed. This reaction works in aqueous media under very mild conditions. This reaction is atom economic. A wide variety of vinylic sulfones could be obtained in moderate to excellent yields with wide functional group tolerance. The efficiency of this method is demonstrated in some reactions where the desired products can be isolated by filtration.
- Goh, Jeffrey,Maraswami, Manikantha,Loh, Teck-Peng
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p. 1060 - 1065
(2021/02/16)
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- Allenone-Mediated Racemization/Epimerization-Free Peptide Bond Formation and Its Application in Peptide Synthesis
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Allenone has been identified as a highly effective peptide coupling reagent for the first time. The peptide bond was formed with an α-carbonyl vinyl ester as the key intermediate, the formation and subsequent aminolysis of which proceed spontaneously in a racemization-/epimerization-free manner. The allenone coupling reagent not only is effective for the synthesis of simple amides and dipeptides but is also amenable to peptide fragment condensation and solid-phase peptide synthesis (SPPS). The robustness of the allenone-mediated peptide bond formation was showcased incisively by the synthesis of carfilzomib, which involved a rare racemization-/epimerization-free N to C peptide elongation strategy. Furthermore, the successful synthesis of the model difficult peptide ACP (65-74) on a solid support suggested that this method was compatible with SPPS. This method combines the advantages of conventional active esters and coupling reagents, while overcoming the disadvantages of both strategies. Thus, this allenone-mediated peptide bond formation strategy represents a disruptive innovation in peptide synthesis.
- Wang, Penghui,Wang, Xuewei,Wang, Zhengning,Zhao, Junfeng
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p. 10374 - 10381
(2021/07/26)
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- A bicyclization reaction with two molecular allenyl ketones and isocyanides: Synthesis of a lactone-containing azaspirocycle derivative
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A novel bicyclization reaction of two molecular allenyl ketones and isocyanides has been disclosed. This strategy allows for the construction of structurally complex spirocyclic lactam-lactone systems in an efficient manner. This protocol also demonstrate
- Yuan, Hongdong,Tang, Chongrong,Su, Shikuan,Cui, Lei,Jia, Xueshun,Li, Chunju,Li, Jian
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p. 7231 - 7234
(2019/07/02)
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- Cycloisomerization of Conjugated Allenones into Furans under Mild Conditions Catalyzed by Ligandless Au Nanoparticles
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Au nanoparticles supported on TiO2 (1 mol %) catalyze the quantitative cycloisomerization of conjugated allenones into furans under very mild conditions. The reaction rate is accelerated by adding acetic acid (1 equiv), but the acid does not participate in the protodeauration step as in the corresponding Au(III)-catalyzed transformation. The process is purely heterogeneous, allowing thus the recycling and reuse of the catalyst effectively in several runs.
- Zorba, Leandros,Kidonakis, Marios,Saridakis, Iakovos,Stratakis, Manolis
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p. 5552 - 5555
(2019/08/01)
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- Diverging Pathways in the Activation of Allenes with Lewis Acids and Bases: Addition, 1,2-Carboboration, and Cyclization
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The reactions of allenes with frustrated (or cooperative) Lewis acid/base pairs result in the 1,4-addition of the base pair to the allene. The reactions of allenyl ketones and esters just in the presence of the strong Lewis acid B(C6F5/su
- Melen, Rebecca L.,Wilkins, Lewis C.,Kariuki, Benson M.,Wadepohl, Hubert,Gade, Lutz H.,Hashmi, A. Stephen K.,Stephan, Douglas W.,Hansmann, Max M.
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p. 4127 - 4137
(2015/09/01)
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- Room temperature Fe(NO3)3·9H 2O/TEMPO/NaCl-catalyzed aerobic oxidation of homopropargylic alcohols
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A practical and eco-friendly aerobic oxidation of homopropargylic alcohols using Fe(NO3)3·9H2O/TEMPO/NaCl as catalysts at room temperature under atmospheric pressure was developed affording corresponding homopropargylic ke
- Liu, Jinxian,Ma, Shengming
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p. 10161 - 10167
(2013/11/06)
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- PROCESS FOR PRODUCING ALDEHYDES OR KETONES BY OXIDIZING ALCOHOLS WITH OXYGEN
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Provided is a process for producing aldehydes or ketones by oxidizing alcohols with oxygen, which comprises oxidizing alcohols to aldehydes or ketones in an organic solvent at room temperature with oxygen or air as an oxidant, wherein ferric nitrate (Fe(NO3)3.9H2O), 2,2,6,6-tetramethylpiperidine N-oxyl (TEMPO) and an inorganic chloride are used as catalysts, the reaction time is 1-24 hours, and the molar ratio of said alcohols, 2,2,6,6-tetramethylpiperidine N-oxyl and the inorganic chloride is 100:1?10:1?10:1?10. The present process has the advantages of high yield, mild reaction conditions, simple operation, convenient separation and purification, recoverable solvents, substrates used therefor being various and no pollution, and therefore it is adaptable to industrialization.
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Page/Page column 3
(2012/09/10)
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- Synthesis of 1,2-allenic ketones through oxidation of homopropargyl alcohols with CrO3(cat.)/TBHP under MWI
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A CrO3 catalyzed oxidation of homopropargyl alcohols with tert-butyl hydroperoxide under microwave irradiation was found to be an efficient and rapid alternative for the preparation of 1,2-allenic ketones. The advantages of this procedure inclu
- Zhang, Xin Ying,Qu, Ying Ying,Wang, Yang Yang,Fan, Xue Sen
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experimental part
p. 268 - 271
(2012/01/30)
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- Tandem reactions of 1,2-allenic ketones leading to substituted benzenes and α,β-unsaturated nitriles
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One-pot double Michael addition/intramolecular aldol reaction/ decarboxylation of 1,2-allenic ketones with cyanoacetate offers an efficient and convenient approach to highly functionalized benzenes. With 2-substituted cyanoacetates, the reaction proceeds via a different tandem process to afford α,β-unsaturated nitriles effectively.
- Zhang, Xinying,Jia, Xuefei,Fang, Liangliang,Liu, Nan,Wang, Jianji,Fan, Xuesen
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supporting information; experimental part
p. 5024 - 5027
(2011/11/12)
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- Development of a general and practical iron nitrate/TEMPO-catalyzed aerobic oxidation of alcohols to aldehydes/ketones: Catalysis with table salt
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Oxidation of alcohols is a fundamental transformation related to our daily life. Traditional approaches with at least one stoichiometric amount of oxidants are expensive and cause serious environmental burdens. There are many reports on the aerobic oxidation of simple alcohols such as alkyl or phenyl carbinols and allylic alcohols, which used oxygen or air as the environmentally benign oxidant forming water as the only by-product. However, no such protocol has been reported for allenols and propargylic alcohols. Thus, it still highly desirable to develop efficient room temperature oxidations of alcohols with a wide scope including allenols and propargylic alcohols. In this paper, an efficient and clean aerobic oxidation of so far the widest spectrum of alcohols using 1 atm of oxygen or air, producing aldehydes/ketones at room temperature in fairly high isolated yields mostly within a couple of hours is described. It is interesting to observe that the reaction has been efficiently expedited by a catalytic amount of sodium chloride in easily recoverable 1,2-dichloroethane. A mechanism involving NO and NO2 has been proposed based on the results of the control experiments and GC-MS studies of the in-situ formed gas phase of the reaction mixture.
- Ma, Shengming,Liu, Jinxian,Li, Suhua,Chen, Bo,Cheng, Jiajia,Kuang, Jinqiang,Liu, Yu,Wan, Baoqiang,Wang, Yuli,Ye, Juntao,Yu, Qiong,Yuan, Weiming,Yu, Shichao
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experimental part
p. 1005 - 1017
(2011/06/17)
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- InI3- or ZnI2-catalyzed reaction of hydroxylated 1,5-allenynes with thiols: A new access to 3,5-disubstituted toluene derivatives
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Transition-metal-activated alkynes or allenes can accept nucleophilic attack and undergo direct addition of the nucleophiles to the unsaturated bonds or trigger subsequent rearrangement reactions. This chemistry has witnessed increasing development in recent years. In this report, we have focused on the metal-catalyzed reactions of a variety of substituted propargyl allenic alcohols and thiophenols using indiumACHTUNGTRENUNG(III) and zinc(II) catalysts, which can activate both the alcohol and alkyne. In this reaction, thio groups play the role of a nucleophile and trigger subsequent rearrangements to give benzene derivatives. The products can be further transformed into various 1,3,5-trisubstituted aromatic compounds by nickel-catalyzed coupling reactions through the cleavage of the C-S bonds.
- Ma, Jie,Peng, Lingling,Zhang, Xiu,Zhang, Zhe,Campbell, Melody,Wang, Jianbo
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p. 2214 - 2220
(2011/06/19)
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- Ru(III)-catalyzed oxidation of homopropargyl alcohols in ionic liquid: an efficient and green route to 1,2-allenic ketones
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An efficient and environmentally benign synthesis of 1,2-allenic ketones via RuCl3-catalyzed oxidation of homopropargyl alcohols in ionic liquid with tert-butyl hydroperoxide (TBHP) as the oxidant was reported for the first time. With its reasonable efficiency and green nature, this oxidation provides a novel alternative route to 1,2-allenic ketones.
- Fan, Xuesen,Qu, Yingying,Wang, Yangyang,Zhang, Xinying,Wang, Jianji
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scheme or table
p. 2123 - 2126
(2010/06/14)
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- The high stereoselective synthesis of β-alkynyl-enol phosphates
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A high stereoselective synthesis for β-alkynyl-enol phosphates from β-alkynyl ketone and dialkyl phosphite, via Atherton-Todd reaction, was reported. NaH as base gave a nearly pure Z-isomer.
- Ding,Huang
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p. 449 - 454
(2007/10/03)
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- C-C-Bond Formation by the Palladium-Catalyzed Cycloisomerization/Dimerization of Terminal Allenyl Ketones: Selectivity and Mechanistic Aspects
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The scope of the palladium-catalyzed cyclization/dimerization of terminal allenyl ketones 1 to the 2,4-disubstituted furans 3 has been investigated. Simplified and improved conditions almost exclusively provided the dimer 3, accompanied by only traces of the easily separable monomer 2. The formation of an isomer of 3, the unconjugated ketone 4, was completeley suppressed. Under these mild conditions, besides the normal functional group tolerance known for palladium-catalyzed reactions, an interesting selectivity was observed with functional groups that are known to react either in palladium-catalyzed reactions or reactions catalyzed by other transition-metals. Thus aryl halides, terminal alkynes, 1,6-enynes, and α-allenic alcohols were tolerated. In the latter example the selective reaction of only one out of two different allenes was achieved. Mechanistic investigation indicated a Pd(II)/Pd(IV)-cycle involving palladium(II)-γ-alkoxyvinylcarbene and furylpalladium(IV) hydride intermediates, although a second pathway for the formation of the dimer 3 which also involves Pd(IV)-intermediates like the 3,4-dimethylenepalladacyclopentane 23 and the 3-methylenepalladacyclobutane-like structure 15 (respectively 25) could not completely be excluded.
- Hashmi, A. Stephen K.,Ruppert, Thorsten L.,Knoefel, Thomas,Bats, Jan W.
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p. 7295 - 7304
(2007/10/03)
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