- Visible Light-Induced Reductive Alkynylation of Aldehydes by Umpolung Approach
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Reductive alkynylation of aldehydes by the Umpolung approach was developed using a photoredox catalyst under blue LED irradiation. Ketyl radicals, generated by single-electron reduction of aldehydes through proton-coupled electron transfer (PCET), reacted with electrophilic alkynylsulfones. Sterically demanding bulky aldehydes reacted smoothly under the Umpolung reaction conditions. Moreover, the alkynylation proceeded chemoselectively with an aryl aldehyde group in the presence of other carbonyl groups including an aliphatic aldehyde group.
- Tanaka, Ibuki,Sawamura, Masaya,Shimizu, Yohei
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supporting information
p. 520 - 524
(2022/01/20)
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- Propargylation of CoQ0 through the Redox Chain Reaction
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An efficient catalytic propargylation of CoQ0 is described by employing the cooperative effect of Sc(OTf)3 and Hantzsch ester. It is suggested to work through the redox chain reaction, which involves hydroquinone and dimeric propargylic moiety intermediates. A broad range of propargylic alcohols can be converted into the appropriate derivatives of CoQ0 containing triple bonds in good to excellent yields. The mechanism of the given transformation is also discussed.
- Mlynarski, Jacek,Pawlowski, Robert,Stodulski, MacIej
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- Multisubstituted pyrazole synthesis via [3?+?2] cycloaddition/rearrangement/N[sbnd]H insertion cascade reaction of α-diazoesters and ynones
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The cascade reactions of alkyl α-diazoesters and ynones using Al(OTf)3 as the catalyst are described. A series of 4-substituted pyrazoles were obtained via [3 + 2] cycloaddition, 1,5-ester shift, 1,3-H shift, and N[sbnd]H insertion process. Deuterium labelling experiments, kinetic studies and control experiments were carried out for the rationalization of the mechanism.
- Feng, Xiaoming,Liu, Xiaohua,Zeng, Zi,Zhao, Peng
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supporting information
p. 132 - 135
(2020/12/21)
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- Sc(OTf)3-catalyzed [3 + 2]-cycloaddition of nitrones with ynones
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An efficient approach to access functionalized (2,3-dihydroisoxazol-4-yl) ketones has been developed by reacting nitrones 4 with ynones 7 or terminal ynones 10 in a one-pot fashion. The reaction went through a formal Sc(OTf)3-catalyzed [3 + 2]-cycloaddition process to generate a number of functionalized (2,3-dihydroisoxazol-4-yl) ketones 11aa-11aw, 11ba-11la and 12aa-12ae in moderate to good yields. This journal is
- He, Chun-Ting,Han, Xiao-Li,Zhang, Yan-Xue,Du, Zhen-Ting,Si, Chang-Mei,Wei, Bang-Guo
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supporting information
p. 457 - 466
(2021/01/29)
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- Enantioselective Inverse Electron Demand (3 + 2) Cycloaddition of Palladium-Oxyallyl Enabled by a Hydrogen-Bond-Donating Ligand
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Cycloaddition reactions between oxyallyl cations and alkenes are important transformations for the construction of ring systems. Although (4 + 3) cycloaddition reactions of oxyallyl cations are well-developed, (3 + 2) cycloadditions remain rare, and an as
- Zheng, Yin,Qin, Tianzhu,Zi, Weiwei
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supporting information
p. 1038 - 1045
(2021/01/25)
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- New α-Hydroxy-1,2,3-triazoles and 9H-Fluorenes-1,2,3-triazoles: H Synthesis and Evaluation as Glycine Transporter 1 Inhibitors
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Two series of new compounds containing 1,2,3-triazole moiety were designed as putative GlyT1 inhibitors aiming the discovery of new hits with activity in cognitive disorders. 1,4-Disubstituted α-hydroxy-1,2,3-triazoles were obtained as racemates in moderate to good yields by the copper-catalyzed azide-alkyne cycloaddition (CuAAC) reaction (click chemistry) as the key step between propargyl alcohols and aryl azides, previously prepared from anilines or boronic acids. Benzo[c]chromene-triazoles were planned to be obtained by palladium-catalyzed C?H activation using [bis(trifluoroacetoxy)iodobenzene] (PhI(TFA)2) of some α-hydroxy-1,2,3-triazoles, since benzo[c]chromenes are also privileged groups with several biological activities, including to the central nervous system. Unexpectedly, 9H-fluorenes-1,2,3-triazoles, instead of benzo[c]chromenetriazoles, were obtained by Friedel-Crafts alkylation reaction. The two series of compounds were tested for inhibition of the glycine transporter (rat GlyT1 isoform) but only the α-hydroxy-1,2,3-triazole 9b was active (half maximal inhibitory concentration (IC50) = 8.0 μM).
- Buarque, Camilla D.,Guimar?es, Marilia Z.,López?Corcuera, Beatriz,Neto, Jo?o Gon?alves,No?l, Fran?ois,Silva, Rafaela R.,da Silva, Veronica D.
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p. 1258 - 1269
(2020/10/14)
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- Gold-Catalyzed Dehydrogenative Cycloisomerization of 1,4-Enyne Esters to 3,5-Disubstituted Phenol Derivatives
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A method to prepare synthetically important 3,5-disubstituted phenol derivatives that relies on the sequential gold(I)-catalyzed dehydrogenative cycloisomerization of 1,4-enyne esters in the presence of 2,3-dichloro-5,6-dicyanobenzoquinone (DDQ) or N-fluorobenzenesulfonimide (NFSI) is described. The synthetic versatility of the methodology was exemplified by a gram-scale reaction of one example, the ease to realize subsequent functional transformations of an adduct, and the application of the method to the synthesis of the bioactive molecule LUF5771. (Figure presented.).
- Chen, Cuili,Chen, Xianxiao,Zhang, Xiaoxiang,Wang, Shifa,Rao, Weidong,Chan, Philip Wai Hong
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supporting information
p. 4359 - 4368
(2017/12/26)
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- Trialkyl Methanetricarboxylate as Dialkyl Malonate Surrogate in Copper-Catalyzed Enantioselective Propargylic Substitution
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The first copper-catalyzed enantioselective propargylation of trialkyl methantricarboxylate with propargylic alcohol derivatives was developed. The tricarboxylate unit in the obtained adducts could be easily transformed into a malonate moiety by treating with in situ generated NaOEt in excellent yield without racemization.
- Huang, Guanxin,Cheng, Cang,Ge, Luo,Guo, Beibei,Zhao, Long,Wu, Xiaoyu
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supporting information
p. 4894 - 4897
(2015/10/12)
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- Cyclopropanation of strained alkenes by palladium-catalyzed reaction of 3-trimethylsilyl- or 3-pinacolatoboryl-1-arylallyl acetates
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The palladium-catalyzed cyclopropanation of strained alkenes with 3-trimethylsilyl- or 3-pinacolatoboryl-1-arylallyl acetate derivatives is described. This reaction gives cyclopropanation products in good to high yields with a single diastereomer, and the key step is likely to involve the formation of a palladacyclobutene complex from the α-trimethylsilyl- or α-pinacolatoboryl-σ-allylpalladium complex. Copyright
- Horino, Yoshikazu,Homura, Naoki,Inoue, Kana,Yoshikawa, Saori
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supporting information; experimental part
p. 828 - 834
(2012/05/04)
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- Synthesis of allenes via gold-catalyzed intermolecular reaction of propargylic alcohols and aromatic compounds
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Functionalized allenes are efficiently synthesized in moderate to high yield from gold-catalyzed intermolecular reaction of propargylic alcohols and aromatic compounds. The user-friendly process could be conducted under mild reaction conditions with easily accessible starting materials.
- Xu, Cheng-Fu,Xu, Mei,Yang, Liu-Qing,Li, Chuan-Ying
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experimental part
p. 3010 - 3016
(2012/05/05)
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- Rhodium-catalyzed intra- and intermolecular [5 + 2] cycloaddition of 3-acyloxy-1,4-enyne and alkyne with concomitant 1,2-acyloxy migration
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A new type of rhodium-catalyzed [5 + 2] cycloaddition was developed for the synthesis of seven-membered rings with diverse functionalities. The ring formation was accompanied by a 1,2-acyloxy migration event. The five- and two-carbon components of the cycloaddition are 3-acyloxy-1,4-enynes (ACEs) and alkynes, respectively. Cationic rhodium(I) catalysts worked most efficiently for the intramolecular cycloaddition, while only neutral rhodium(I) complexes could facilitate the intermolecular reaction. In both cases, electron-poor phosphite or phosphine ligands often improved the efficiency of the cycloadditions. The scope of ACEs and alkynes was investigated in both the intra- and intermolecular reactions. The resulting seven-membered-ring products have three double bonds that could be selectively functionalized.
- Shu, Xing-Zhong,Li, Xiaoxun,Shu, Dongxu,Huang, Suyu,Schienebeck, Casi M.,Zhou, Xin,Robichaux, Patrick J.,Tang, Weiping
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supporting information; experimental part
p. 5211 - 5221
(2012/05/05)
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- Gold-catalyzed regioselective hydration of propargyl acetates assisted by a neighboring carbonyl group: Access to α-acyloxy methyl ketones and synthesis of (±)-actinopolymorphol B
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A general atom-economical approach for the synthesis of α-acyloxy methyl ketone is demonstrated through regioselective hydration of a wide range of propargyl acetates. Readily available catalyst comprising of 1% Ph 3PAuCl and 1% AgSbF6 in dioxane-H2O efficiently hydrolyzes the terminal alkynes of the propargyl acetate in the absence of acid promoters at ambient temperature within a short time. Effective regioselective hydration is facilitated by the neighboring carbonyl group as demonstrated through 18O-labeling study. Compatibility of functional moieties and tolerance to various acid-labile protecting groups are observed. The catalytic condition is also suitable to perform hydration of TMS-substituted propargyl acetates, even though it requires prolonged reaction time for completion. Stereointegrity of the propargylic acetate is preserved during the hydration. The robustness of the system is successfully demonstrated through gram scale preparation of the product in nearly quantitative yield. The common α-acyloxy methyl ketone is transformed to 1,2-diol and 1,2-amino alcohol derivatives. Synthesis of actinopolymorphol B is achieved for the first time involving hydration of the propargyl acetate as the key step.
- Ghosh, Nayan,Nayak, Sanatan,Sahoo, Akhila K.
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supporting information; experimental part
p. 500 - 511
(2011/04/17)
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- Base-catalyzed cascade 1,3-H shift/cyclization reaction to construct polyaromatic furans
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A convenient new method was developed to prepare unfused polyaromatic furan derivatives from diynyl-1,6-diols through a novel base-catalyzed cascade 1,3-H shift/cyclization process. Deuterium experiments were performed to determine that the 1,3-H shift was the rate-determining step. Copyright
- Wang, Ya-Hui,Liu, Heng,Zhu, Li-Li,Li, Xiao-Xiao,Chen, Zili
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supporting information; experimental part
p. 707 - 712
(2011/05/06)
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