- Direct (Hetero)arylation of Heteroarenes Catalyzed by Unsymmetrical Pd-PEPPSI-NHC Complexes under Mild Conditions
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With the aim of developing a facile and efficient method to access structurally intriguing and valuable functionalized (hetero)aryls, two unsymmetrical Pd-PEPPSI-type NHC complexes (PEPPSI, pyridine-enhanced precatalyst preparation, stabilization, and initiation; NHC, N-heterocyclic carbene) were designed and synthesized to catalyze the direct arylation of heteroarenes with (hetero)aryl bromides. The results demonstrated that the utilization of this "unsymmetrical"strategy led to much higher efficiency in comparison to the commonly used C2-symmetric Pd-PEPPSI-type NHC complexes. Furthermore, a broad range of heteroaromatics and (hetero)aryl bromide partners with a wide variety of functional groups were all amenable to the developed protocol even at as low as 0.05 mol % catalyst loading and under aerobic conditions. More importantly, along with our study, we also found that the present protocol could provide expedient access to the gram-scale synthesis of the muscle relaxant drug dantrolene and conjugated mesopolymers.
- Song, A-Xiang,Zeng, Xiao-Xiao,Ma, Bei-Bei,Xu, Chang,Liu, Feng-Shou
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p. 3524 - 3534
(2020/10/09)
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- Auto-Tandem Catalysis-Induced Synthesis of Trisubstituted Furans through Domino Acid-Acid-Catalyzed Reaction of Aliphatic Aldehydes and 1,3-Dicarbonyl Compounds by using N-Bromosuccinimide as Oxidant
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A simple aluminium(III) chloride-catalyzed synthesis of tri-substituted furans from aliphatic aldehydes and 1,3-dicarbonyl compounds was developed by using N-bromosuccinimide (NBS) as an oxidant. This method was effective for the synthesis of various furan derivatives. Some of the products were not accessible with the previously reported methods. Mechanically, this reaction involved an auto-tandem catalysis based on a newly reported acid-acid-catalyzed tandem reaction to ensure that furans were successfully synthesized. (Figure presented.).
- Huang, Wenbo,Liu, Changhui,Gu, Yanlong
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p. 1811 - 1818
(2017/06/09)
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- Palladium Complexes with Tetrahydropyrimidin-2-ylidene Ligands: Catalytic Activity for the Direct Arylation of Furan, Thiophene, and Thiazole Derivatives
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The synthesis and characterization of novel 1,3-benzyl-3,4,5,6-tetrahydropyrimidin-2-ylidene-based N-heterocyclic carbene palladium(II) complexes (1a-d) were described. The crystal structure of trans-dichlorobis[1,3-bis(4-methylbenzyl)-3,4,5,6-tetrahydrop
- Karaca, Emine ?zge,Gürbüz, Nevin,?zdemir, Ismail,Doucet, Henri,?ahin, Onur,Büyükgüng?r, Orhan,?etinkaya, Bekir
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p. 2487 - 2493
(2015/06/25)
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- Tuning radical reactivity using iodine in oxidative C(sp3)-H/C(sp)-H cross-coupling: An easy way toward the synthesis of furans and indolizines
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Molecular iodine was found to be an effective redox catalyst for the oxidative cross-coupling of carbonyl compounds with terminal alkynes. In this work, we demonstrated that iodine could tune radical reactivity through reversible C-I bond formation for co
- Tang, Shan,Liu, Kun,Long, Yue,Qi, Xiaotian,Lan, Yu,Lei, Aiwen
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p. 8769 - 8772
(2015/05/20)
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- Cobalt(II)-catalyzed electrophilic alkynylation of 1,3-dicarbonyl compounds to form polysubstituted furans via π-π Activation
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Polysubstituted furans were obtained with excellent yields via the electrophilic alkynylation of 1,3-dicarbonyl compoundsws with phenyl- or ester-substituted brominated alkynes. The reaction is catalyzed by the inexpensive and readily available catalyst, cobalt(II) chloride, and has a wide substrate scope. The C(sp)-C(sp3) coupling occurs under mild conditions with short reaction times and does not require an inert atmosphere or ligands. It is proposed that the reaction proceeds through a chelation complex of cobalt(II) with the deprotonated 1,3-dicarbonyl compound.
- Roslan, Irwan Iskandar,Sun, Jiulong,Chuah, Gaik-Khuan,Jaenicke, Stephan
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p. 719 - 726
(2015/03/18)
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- Regioselective synthesis of highly functionalized furans through the RuII-catalyzed [3+2] cycloaddition of diazodicarbonyl compounds
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A novel method for the RuII-catalyzed regioselective synthesis of highly functionalized furans from readily available cyclic and acyclic diazodicarbonyl compounds and terminal alkynes is described. The devised protocol offers a straightforward means to the construction of a variety of diverse furan derivatives through powerful cascade processes, including the formation of ruthenium carbenoid, cyclopropenation, ring-opening metathesis, and cyclization. Copyright
- Xia, Likai,Lee, Yong Rok
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p. 3430 - 3442
(2014/06/09)
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- Pd(II)-catalyzed sequential C-C/C-O bond formations: A new strategy to construct trisubstituted furans
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Palladium-catalyzed oxidative difunctionalization of enol ethers with 1,3-dicarbonyl compounds to construct trisubstituted furans in one step under mild conditions is described. The reaction is thought to proceed through a C-C bond formation along with a C-O bond closing the ring structure. Oxygen is the sole oxidant regenerating the Pd(II) catalyst.
- Zheng, Meifang,Huang, Liangbin,Wu, Wanqing,Jiang, Huanfeng
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supporting information
p. 1838 - 1841
(2013/06/04)
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- Silver-mediated oxidative C-H/C-H functionalization: A strategy to construct polysubstituted furans
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A novel silver-mediated highly selective oxidative C-H/C-H functionalization of 1,3-dicarbonyl compounds with terminal alkynes for the creation of polysubstituted furans and pyrroles in one step has been demonstrated. Promoted by the crucial silver specie
- He, Chuan,Guo, Sheng,Ke, Jie,Hao, Jing,Xu, Huan,Chen, Hongyi,Lei, Aiwen
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supporting information; experimental part
p. 5766 - 5769
(2012/05/07)
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- Discovery and hit-to-lead optimization of novel allosteric glucokinase activators
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We report on a hit generation and hit-to-lead program of a novel class of glucokinase activators (GKAs). Hit compounds, activators at low glucose concentration only were identified by vHTS. Scaffold modification reliably afforded activators also at high s
- Lang, Martin,Seifert, Markus H.-J.,Wolf, Kristina K.,Aschenbrenner, Andrea,Baumgartner, Roland,Wieber, Tanja,Trentinaglia, Viola,Blisse, Marcus,Tajima, Nobumitsu,Yamashita, Tokuyuki,Vitt, Daniel,Noda, Hitoshi
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supporting information; scheme or table
p. 5417 - 5422
(2011/10/12)
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- Rh2(S-PTAD)4-catalyzed asymmetric cyclopropenation of aryl alkynes
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Rh2(S-PTAD)4 is an effective catalyst for the asymmetric cyclopropenation of aryl alkynes using a siloxyvinyldiazoacetate as the carbenoid precursor. Upon deprotection of the silyl protecting group, highly enantioenriched cyclopropen
- Briones, John F.,Davies, Huw M.L.
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p. 4313 - 4317
(2011/07/29)
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- Synthesis of 2,3,5-Trisubstituted Furans by the Acid-Catalyzed Decomposition of 1,2-Dioxan-3-ols
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Thirteen new 2,3,5-trisubstituted furans were prepared by the acid-catalyzed decomposition of 6,6-disubstituted 1,2-dioxan-3-ols in 57-93percent yields.The reaction could be accounted for as the consequence of an oxygen-oxygen bond cleavage by acid and the migration of a phenyl group at the C-6 position followed by cyclization and elimination of a phenol.The migratory aptitude was in the order of 4-MeOC6H4- greater than 4-MeO6H4- greater than Ph- = 4-FC6H4- greater than 4-ClC6H4- = 4-BrC6H4- that was found from the competitive phenyl migration in the reaction of 1,2-dioxan-3-ols bearing two different substituents at the C-6 position.
- Qian, Chang-Yi,Hirose, Jun-ichi,Nishino, Hiroshi,Kurosawa, Kazu
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p. 1219 - 1228
(2007/10/02)
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- PHOTOSENSITIZED Oxidation of Furans. Part 4. Influence of the Substituents on the Behaviour of the endo-Peroxides of Furans
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A comparison of the ehaviour of endo-peroxides of the β-furoic esters (1a, b and d-f) and of the furans (1c or g), with the same 2,5-substituents, shows that the thermal instability of these compounds is related to the electron density in the bicyclic unsaturated ring.This also accounts for the higher stability of the alkyl-substituted endo-peroxides (1a-c) as compared with that of the aryl-substituted derivatives (1d-g), as well as for the different course of the thermal conversion in the two series.
- Graziano, M. Liliana,Iesce, M. Rosaria,Scarpati, Rachele
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p. 2007 - 2012
(2007/10/02)
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- Photosensitized Oxidation of Furans. III. Comparison Between Photochemically and Thermally Generated Singlet Oxygen Oxidation of 3-Methoxycarbonyl-2-methyl-5-phenylfuran
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Thermal conversion of furan endo-peroxide I, obtained by photosensitized oxidation of furan II, yields very similar results to those of the oxidation of the furan II by thermally generated singlet oxygen, showing that also in the latter case the endo-peroxide I is the key intermediate.A mechanistic interpretation of the furan II-singlet oxygen reaction is reported.
- Graziano, M. L.,Iesce, M. R.,Carli, B.,Scarpati, R.
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p. 1105 - 1107
(2007/10/02)
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