- Monocarboxylation and intramolecular coupling of butenylated arenes via palladium-catalyzed C-H activation process
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A novel and practical reaction for the direct intramolecular oxidative coupling of butenylated arenes is reported. With the catalysis of Pd(OAc)2, reactions of various butenylated arenes and carboxylic acids with Selectfluor reagent in CH3CN solution afforded the corresponding monocarboxylation/cyclization products in good yields under mild conditions. This research demonstrated an economic method with the synthesis of 2-tetralyl carboxylic esters, a valuable class of bioactive compounds.
- Liu, Rui,Lu, Ze-Hai,Hu, Xiao-Hui,Li, Jun-Li,Yang, Xian-Jin
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- Ni-Catalyzed Carboxylation of Aziridines en Route to β-Amino Acids
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A Ni-catalyzed reductive carboxylation of N-substituted aziridines with CO2 at atmospheric pressure is disclosed. The protocol is characterized by its mild conditions, experimental ease, and exquisite chemo- and regioselectivity pattern, thus unlocking a new catalytic blueprint to access β-amino acids, important building blocks with considerable potential as peptidomimetics.
- Davies, Jacob,Janssen-Müller, Daniel,Zimin, Dmitry P.,Day, Craig S.,Yanagi, Tomoyuki,Elfert, Jonas,Martin, Ruben
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p. 4949 - 4954
(2021/04/07)
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- Access to Trisubstituted Fluoroalkenes by Ruthenium-Catalyzed Cross-Metathesis
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Although the olefin metathesis reaction is a well-known and powerful strategy to get alkenes, this reaction remained highly challenging with fluororalkenes, especially the Cross-Metathesis (CM) process. Our thought was to find an easy accessible, convenient, reactive and post-functionalizable source of fluoroalkene, that we found as the methyl 2-fluoroacrylate. We reported herein the efficient ruthenium-catalyzed CM reaction of various terminal and internal alkenes with methyl 2-fluoroacrylate giving access, for the first time, to trisubstituted fluoroalkenes stereoselectively. Unprecedent TON for CM involving fluoroalkene, up to 175, have been obtained and the reaction proved to be tolerant and effective with a large range of olefin partners giving fair to high yields in metathesis products. (Figure presented.).
- Nouaille, Augustin,Pannecoucke, Xavier,Poisson, Thomas,Couve-Bonnaire, Samuel
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p. 2140 - 2147
(2021/03/06)
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- Designed electron-deficient gold nanoparticles for a room-temperature Csp3-Csp3coupling reaction
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Stille cross-coupling reactions catalysed by an ideal catalyst combining the high activity of homogeneous catalysts and the reusability of heterogeneous catalysts are of great interest for C-C bond formation, which is a widely used reaction in fine chemistry. Despite great effort to increase the utilization ratio of surface metal atoms, the activity of heterogeneous catalysts under mild conditions remains unsatisfactory. Herein, we design a proof-of-concept strategy to trigger the room-temperature activity of heterogeneous Au catalysts by decreasing the electron density at the interface of a rationally designed Schottky heterojunction of Au metals and boron-doped carbons. The electron-deficient Au nanoparticles formed as a result of the rectifying contact with boron-doped carbons facilitate the autocleavage of C-Br bonds for highly efficient C-C coupling reactions of alkylbromides and allylstannanes with a TOF value of 5199 h-1 at room temperature, surpassing that of the state-of-the-art homogeneous catalyst. This journal is
- Yu, Qiu-Ying,Su, Hui,Zhai, Guang-Yao,Zhang, Shi-Nan,Sun, Lu-Han,Chen, Jie-Sheng,Li, Xin-Hao
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p. 741 - 744
(2021/02/06)
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- In Situ Generated Gold Nanoparticles on Active Carbon as Reusable Highly Efficient Catalysts for a Csp3 ?Csp3 Stille Coupling
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Gold nanoparticle catalysts are important in many industrial production processes. Nevertheless, for traditional Csp2-Csp2 cross-coupling reactions they have been rarely used and Pd catalysts usually give a superior performance. Herein we report that in situ formed gold metal nanoparticles are highly active catalysts for the cross coupling of allylstannanes and activated alkylbromides to form Csp3-Csp3 bonds. Turnover numbers up to 29 000 could be achieved in the presence of active carbon as solid support, which allowed for convenient catalyst recovery and reuse. The present study is a rare case where a gold metal catalyst is superior to Pd catalysts in a cross-coupling reaction of an organic halide and an organometallic reagent.
- Holz, Julia,Pfeffer, Camilla,Zuo, Hualiang,Beierlein, Dennis,Richter, Gunther,Klemm, Elias,Peters, René
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p. 10330 - 10334
(2019/06/27)
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- Umpolung of Carbonyl Groups as Alkyl Organometallic Reagent Surrogates for Palladium-Catalyzed Allylic Alkylation
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Palladium-catalyzed allylic alkylation of nonstabilized carbon nucleophiles is difficult and remains a major challenge. Reported here is a highly chemo- and regioselective direct palladium-catalyzed C-allylation of hydrazones, generated from carbonyls, as a source of umpolung unstabilized alkyl carbanions and surrogates of alkyl organometallic reagents. Contrary to classical allylation techniques, this umpolung reaction utilizes hydrazones prepared not only from aryl aldehydes but also from alkyl aldehydes and ketones as renewable feedstocks. This strategy complements the palladium-catalyzed coupling of unstabilized nucleophiles with allylic electrophiles by providing an efficient and selective catalytic alternative to the traditional use of highly reactive alkyl organometallic reagents.
- Zhu, Dianhu,Lv, Leiyang,Li, Chen-Chen,Ung, Sosthene,Gao, Jian,Li, Chao-Jun
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p. 16520 - 16524
(2018/11/23)
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- Aerobic Acetoxyhydroxylation of Alkenes Co-catalyzed by Organic Nitrite and Palladium
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An aerobic acetoxyhydroxylation of alkenes cooperatively catalyzed by organic nitrite and palladium at room temperature using clean and cheap air as the sole oxidant has been developed. Various vicinal diols, diacetoxyalkanes, and dihalogenoalkanes have been synthesized. The gram-scale synthesis has also been approached. Vicinal difluorination and dichlorolation products have also been achieved via this reaction.
- Chen, Xian-Min,Ning, Xiao-Shan,Kang, Yan-Biao
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p. 5368 - 5371
(2016/11/02)
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- Wacker-type oxidation and dehydrogenation of terminal olefins using molecular oxygen as the sole oxidant without adding ligand
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An efficient and economical palladium-catalyzed oxidation system has been identified. The oxidation system, characterized by not adding ligand and using molecular oxygen as the sole oxidant, can realize the Tsuji-Wacker oxidation of terminal olefins and especially styrenes to methyl ketones; in addition, this system can achieve tandem Wacker oxidation-dehydrogenation of terminal olefins to α,β-unsaturated ketones.
- Wang, Yu-Fei,Gao, Ya-Ru,Mao, Shuai,Zhang, Yan-Lei,Guo, Dong-Dong,Yan, Zhao-Lei,Guo, Shi-Huan,Wang, Yong-Qiang
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supporting information
p. 1610 - 1613
(2014/04/17)
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- Terminal olefins to linear α,β-unsaturated ketones: Pd(II)/hypervalent iodine co-catalyzed wacker oxidation-dehydrogenation
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Development of a mild (35 C, no Bronsted acids) tandem Wacker oxidation-dehydrogenation of terminal olefins was accomplished using palladium(II) and hypervalent iodine co-catalysis. The reaction affords linear aryl and alkyl α,β-unsaturated ketones directly from readily available terminal olefins in good yields (average 75% per step) with excellent functional group tolerance and chemo- and stereoselectivities. The hypervalent iodine co-catalyst was found to be critical for dehydrogenation but was not effective as a stoichiometric oxidant.
- Bigi, Marinus A.,White, M. Christina
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supporting information
p. 7831 - 7834
(2013/07/19)
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- Catalytic enantioselective allylic amination of olefins for the synthesis of ent -sitagliptin
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The presence of nitrogen atoms in most chiral pharmaceutical drugs has motivated the development of numerous strategies for the synthesis of enantiomerically enriched amines. Current methods are based on multistep transformations of functionalized allylic electrophiles to form chiral allylic amines. The enantioselective allylic amination of nonactivated olefins would represent a more direct and more attractive strategy. We report the enantio selective synthesis of ent-sitagliptin through an allylic amination of a nonactivated terminal olefin. Georg Thieme Verlag Stuttgart, New York.
- Bao, Hongli,Bayeh, Liela,Tambar, Uttam
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supporting information
p. 2459 - 2463
(2013/11/06)
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- Picosecond radical kinetics. Rate constants for ring openings of 2-aryl-substituted cyclopropylcarbinyl radicals
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The kinetics of ring openings of a series of eight (trans-2-arylcyclopropyl)methyl radicals (1) were studied by indirect kinetic methods using Barton's PTOC esters as radical precursors and reaction with PhSeH as the competition reaction. The substituents were CF3, F, Me, and OMe located on both the para and meta positions of the aromatic ring. Syntheses of the radical precursors and the products of the radical reactions are described. Kinetics were determined between -43 and 25°C in four cases (CF3 and OMe substituents) and at 0 and 25°C in the other four cases. The rate constants at 25°C ranged from 1.0 x 1011 s-1 (p-CH3) to 4.1 x 1011 s-1 (p-CF3). The relatively large acceleration of the p-CF3 group, ca. 2.5 times as fast as the parent system with Ar = Ph, correlates well with Adam's ΔD substituent parameters but not with other radical substituent parameters. These calibrated radical rearrangements provide a new set of ultrafast reactions that can be applied in mechanistic probe studies.
- Newcomb,Choi,Toy
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p. 1123 - 1135
(2007/10/03)
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