- Iridium-catalyzed highly chemoselective and efficient reduction of nitroalkenes to nitroalkanes in water
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An iridium-catalyzed highly chemoselective and efficient transfer hydrogenation reduction of structurally diverse nitroalkenes was realized at very low catalyst loading (S/C = up to 10000 or 20?000), using formic acid or sodium formate as a traceless hydride donor in water. Excellent functionality tolerance is also observed. The turnover number and turnover frequency of the catalyst reach as high as 18?600 and 19?200 h-1, respectively. An inert atmosphere protection is not required. The reactivities of nitroalkenes are dependent on their substitution pattern, and the pH value is a key factor to accomplish the complete conversion and excellent chemoselectivity. Purification of products is achieved by simple extraction without column chromatography. The reduction procedure is facilely amplified to 10 g scale at 10?000 S/C ratio. The potential of this green reduction in enantioselective hydrogenation has been demonstrated.
- Chen, Yang,Liu, Changmeng,Xu, Dong,Xu, Jiaxi,Yang, Zhanhui
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supporting information
p. 6050 - 6058
(2021/08/23)
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- Regio- and Stereoselective Cascade of β,γ-Unsaturated Ketones by Dipeptided Phosphonium Salt Catalysis: Stereospecific Construction of Dihydrofuro-Fused [2,3-b] Skeletons
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Chiral (dihydro)furo-fused heterocycles are significant structural motifs in numerous natural products, functional materials and pharmaceuticals. Therefore, developing efficient methods for preparing compounds with these privileged scaffolds is an important endeavor in synthetic chemistry. Herein, we develop an effective, modular method by a dipeptide-phosphonium salt-catalyzed regio- and stereoselective cascade reaction of readily available linear β,γ-unsaturated ketones with aromatic alkenes, affording a wide variety of structurally fused heterocyclic molecules in high yields with excellent stereoselectivities. Moreover, mechanistic investigations revealed that the bifunctional phosphonium salt controlled the regio- and stereoselectivities of this cascade reaction, particularly proceeding through the initial ketone α-addition followed by O-participated substitution; and the multiple hydrogen-bonding interactions between Br?nsted acid moieties of catalyst and nitro group of aromatic alkene were crucial in asymmetric induction. Given the generality, versatility, and high efficiency of this method, we anticipate that it will have broad synthetic utilities.
- Chen, Yayun,He, Jiajia,Jiang, Chunhui,Ren, Xiaoyu,Su, Zhishan,Wang, Tianli,Xiao, Kai,Zhang, Hongkui,Zhuang, Cheng
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supporting information
p. 19860 - 19870
(2021/08/06)
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- Asymmetric dearomatization of 2-nitrobenzofurans by organocatalyzed one-step Michael addition to access 3,3′-disubstituted oxindoles
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An efficient enantioselective dearomatization of 2-nitrobenzofurans was realized via an organocatalyzed one-step Michael addition process. This method provides a facile strategy to access a range of structurally diverse 3,3′-disubstituted oxindoles, which feature an intriguing combination of two privileged motifs including 3-pyrrolyl-substituted-oxindoles and 2,3-dihydrobenzofurans substructures, in excellent results.
- Ge, Zhen-Zhen,Wang, Zhen-Hua,Xie, Ke-Xin,Yang, Lei,You, Yong,Yuan, Wei-Cheng,Zhao, Jian-Qiang,Zhou, Ming-Qiang
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supporting information
p. 2586 - 2589
(2020/03/10)
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- Facile synthesis of chiral [2,3]-fused hydrobenzofuran: Via asymmetric Cu(i)-catalyzed dearomative 1,3-dipolar cycloaddition
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Intermolecular asymmetric dearomative 1,3-dipolar cycloaddition of 2-nitrobenzofurans with azomethine ylides was enabled by using a chiral Cu(i)/(S,Sp)-iPr-Phosferrox catalyst. As a result, a series of highly stereoselective chiral [2,3]-fused hydrobenzofurans possessing four contiguous stereogenic centers were obtained with good to high yields, diastereoselectivities and enantioselectivities. The reaction has broad substrate scope tolerating various functional groups.
- Liang, Lei,Niu, Hong-Ying,Wang, Dong-Chao,Yang, Xin-He,Qu, Gui-Rong,Guo, Hai-Ming
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supporting information
p. 553 - 556
(2019/01/10)
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- Enantioselective dearomative [3+2] cycloaddition of 2-nitrobenzofurans with aldehyde-derived Morita-Baylis-Hillman carbonates
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The phosphine-catalyzed asymmetric dearomative [3+2] cycloaddition of 2-nitrobenzofurans with aldehyde-derived Morita-Baylis-Hillman (MBH) carbonates or allenoate was developed. The reaction with MBH carbonates resulted in a series of cyclopentabenzofurans containing three contiguous stereocenters with good to high yields, diastereoselectivities and enantioselectivities. The use of allenoate also gave the target product with moderate enantioselectivity.
- Yang, Xin-He,Li, Jian-Ping,Wang, Dong-Chao,Xie, Ming-Sheng,Qu, Gui-Rong,Guo, Hai-Ming
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supporting information
p. 9144 - 9147
(2019/08/07)
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- Synthetic calanolides with bactericidal activity against replicating and nonreplicating mycobacterium tuberculosis
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It is urgent to introduce new drugs for tuberculosis to shorten the prolonged course of treatment and control drug-resistant Mycobacterium tuberculosis (Mtb). One strategy toward this goal is to develop antibiotics that eradicate both replicating (R) and
- Zheng, Purong,Somersan-Karakaya, Selin,Lu, Shichao,Roberts, Julia,Pingle, Maneesh,Warrier, Thulasi,Little, David,Guo, Xiaoyong,Brickner, Steven J.,Nathan, Carl F.,Gold, Ben,Liu, Gang
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supporting information
p. 3755 - 3772
(2014/05/20)
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- Aldehyde-Assisted Ruthenium(II)-Catalyzed C-H Oxygenations
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Versatile ruthenium(II) complexes allow for site-selective C-H oxygenations with weakly-coordinating aldehydes. The challenging C-H functionalizations proceed with high chemoselectivity by rate-determining C-H metalation. The new method features an ample substrate scope, which sets the stage for the step-economical preparation of various bioactive heterocycles.
- Yang, Fanzhi,Rauch, Karsten,Kettelhoit, Katharina,Ackermann, Lutz
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p. 11285 - 11288
(2016/02/18)
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- New approach to oximes through reduction of nitro compounds enabled by visible light photoredox catalysis
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A range of nitro compounds are smoothly reduced to their corresponding oximes under the synergistic effects of visible light irradiation, the Ru(bpy)3Cl2 photocatalyst, Hünig's base, Mg(ClO 4)2 activation, and MeCN solvent. This remarkably mild and environmentally benign protocol, when orchestrated with classical Beckmann rearrangement, enables such high-value industrial feedstock as caprolactam to be readily accessed from simple precursor nitrocyclohexane.
- Cai, Shunyou,Zhang, Shaolong,Zhao, Yaohong,Wang, David Zhigang
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supporting information
p. 2660 - 2663
(2013/07/11)
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- Optimization of the potency and pharmacokinetic properties of a macrocyclic ghrelin receptor agonist (Part I): Development of ulimorelin (TZP-101) from Hit to Clinic
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High-throughput screening of Tranzyme Phar-ma's proprietary macrocycle library using the aequorin Ca2+-bioluminescence assay against the human ghrelin receptor (GRLN) led to the discovery of novel agonists against this G-protein coupled receptor. Early hits such as 1 (Ki = 86 nM, EC50 = 134 nM) though potent in vitro displayed poor pharmacokinetic properties that required optimization. While such macrocycles are not fully rule-of-five compliant, principally due to their molecular weight and clogP, optimization of their pharmacokinetic properties proved feasible largely through conformational rigidification. Extensive SAR led to the identification of 2 (Ki = 16 nM, EC50 = 29 nM), also known as ulimorelin or TZP-101, which has progressed to phase III human clinical trials for the treatment of postoperative ileus. X-ray structure and detailed NMR studies indicated a rigid peptidomimetic portion in 2 that is best defined as a nonideal type-I′ β-turn. Compound 2 is 24% orally bioavailable in both rats and monkeys. Despite its potency, in vitro and in gastric emptying studies, 2 did not induce growth hormone (GH) release in rats, thus demarcating the GH versus GI pharmacology of GRLN. (Figure presented)
- Hoveyda, Hamid R.,Marsault, Eric,Gagnon, René,Mathieu, Axel P.,Vézina, Martin,Landry, Annick,Wang, Zhigang,Benakli, Kamel,Beaubien, Sylvie,Saint-Louis, Carl,Brassard, Martin,Pinault, Jean-Fran?ois,Ouellet, Luc,Bhat, Shridhar,Ramaseshan, Mahesh,Peng, Xiaowen,Foucher, Laurence,Beauchemin, Sophie,Bhérer, Patrick,Veber, Daniel F.,Peterson, Mark L.,Fraser, Graeme L.
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supporting information; experimental part
p. 8305 - 8320
(2012/01/15)
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- Biocatalytic enantioselective approach to 3-aryl-2-nitropropanols: Synthesis of enantioenriched (R)-5-methoxy-3-aminochroman, a key precursor to the antidepressant drug Robalzotan
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The results of our studies on the biocatalytic enantioselective synthesis of different 3-aryl-2-nitropropanols are presented. These compounds could be obtained in moderate to good ee both bybaker's yeast mediated reduction of (E)-2-nitro-3-arylprop-2-en-1-ol precursors and by lipase kinetic resolution of racemic 3-aryl-2-nitropropanols. The synthesis of enantioenriched (R)-5-methoxy-3-aminochroman is also achieved. This important moietyispresent in different molecules active toward the central nervous system and is also the precursor for the synthesis of Robalzotan (NAD299), a potent 5-HT1A antagonist.
- Fuganti, Claudio,Sacchetti, Alessandro
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experimental part
p. 276 - 284
(2010/11/18)
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- A new efficient method for the total synthesis of linear furocoumarins
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A new efficient method for the synthesis of linear furocoumarins by a Nef reaction and intramolecular cyclocondensation in one pot results in the construction of a benzofuran ring. This method provides a new strategy to furnish the benzofuran framework easily, and also allows the convenient synthesis of furocoumarin derivatives with different substituents on the coumarin ring by a subsequent Pechmann reaction. This strategy has also been applied to the preparation of four additional benzofuran derivatives. Georg Thieme Verlag Stuttgart.
- Zhang, Bang-Le,Wang, Fang-Dao,Yue, Jian-Min
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p. 567 - 570
(2007/10/03)
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- 3-Nitrocoumarins as Dienophiles in the Diels-Alder Reaction in Water. An Approach to the Synthesis of Nitrotetrahydrobenzo[c]chromenones and Dihydrodibenzo[b,d]furans
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The [4 + 2] cycloadditions of 3-nitrocoumarin (1a), 6-chloro-3-nitrocoumarin (1b), and 6-, 7-, and 8-hydroxy-3-nitrocoumarins (1c, 5, and 6) with (E)-piperylene (7), isoprene (8), 2,3-dimethyl-1,3-butadiene (9), 2-methoxy-1,3-butadiene (10), 2,3-dimethoxy-1,3-butadiene (11), and cyclopentadiene (12) were investigated in aqueous medium, in organic solvent and under solventless conditions. The reactions performed in water occurred in heterogeneous phase but were faster than those executed in toluene or dichloroethane (DCE). 1a-c, 5, and 6 behaved as 2π components in the Diels-Alder cycloadditions with 7-10 and 12, and exo adducts were preferentially or exclusively produced. Surprisingly 1a, behaved as a 4π component in the cycloaddition in water with 11 and 4-substituted 3-nitrochromanones 20 and 21 were isolated. The cycloadditions of hydroxy-3-nitrocoumarins 1c, 5, and 6 with 1,3-diene 9 did not work in water or in organic solvent, but did work under solventless conditions. Nitrotetrahydrobenzo[c]chromenones 13-16, 24, and 25, originating from the normal electron-demand Diels-Alder reactions, were converted into dihydrodibenzo[b,d]furans 27-31 in water, via one-pot Nef-cyclodehydration reactions.
- Amantini, David,Fringuelli, Francesco,Piermatti, Oriana,Pizzo, Ferdinando,Vaccaro, Luigi
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p. 9263 - 9268
(2007/10/03)
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