- Sequential catalytic carbonylation reactions for sustainable synthesis of biologically relevant entities
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The sustainable synthesis of highly functionalised formylcarboxamide compounds with biological relevance is reported through a sequential aminocarbonylation/hydroformylation approach. The optimisation of palladium-catalysed aminocarbonylation of iodoaromatic substrates, using allylamine as nucleophile was first performed, with molybdenum hexacarbonyl as alternative CO source versus gaseous carbon monoxide. The combination of microwave irradiation with molybdenum hexacarbonyl allowed to selectively prepare a set of N-heterocyclic-based allylcarboxamides. Subsequent rhodium-catalysed hydroformylation of the allylcarboxamide intermediates led to the preparation of new pyridine, pyrazoline and chalcone derivatives containing both carboxamide and formyl moieties.
- Carrilho, Rui M. B.,Damas, Liliana,Gonzalez, Andreia C. S.,Pereira, Mariette M.,Pineiro, Marta,Rodrigues, Fábio M. S.
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- Electrochemical Chalcogenation of β,γ-Unsaturated Amides and Oximes to Corresponding Oxazolines and Isoxazolines
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The current report represents a transition-metal-free synthesis of oxazoline and isoxazoline derivatives by a tandem electro-oxidative chalcogenation-cyclization process. Both C?Se and C?S bond-forming protocols were developed without using any external oxidant and the reaction was performed at room temperature, open to the air. Using this methodology, 29 substituted oxazoline and 16 substituted isoxazoline derivatives were synthesized with up to 91% isolated yield. (Figure presented.).
- Baidya, Mrinmay,De Sarkar, Suman,Mahanty, Kingshuk,Maiti, Debabrata,Mallick, Samrat
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supporting information
(2020/02/04)
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- Electrochemical Fluorocyclization of N-Allylcarboxamides to 2-Oxazolines by Hypervalent Iodine Mediator
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A resource saving protocol for the synthesis of 5-fluoromethyl-2-oxazolines by using electrochemistry has been realized. Thereby, a hypervalent iodine species I(III) is generated by anodic oxidation in the presence of Et3N·5HF and mediates the
- Haupt, John D.,Berger, Michael,Waldvogel, Siegfried R.
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supporting information
p. 242 - 245
(2019/01/04)
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- Preparation of Heterocycles via Visible-Light-Driven Aerobic Selenation of Olefins with Diselenides
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The aerobic dehydrogenative cyclization of alkenes with easily accessible diselenides facilitated by visible light is reported. Notably, the features of this transition-metal-free protocol are pronounced efficiency and practicality, good functional group
- Zhang, Qing-Bao,Yuan, Pan-Feng,Kai, Liang-Lin,Liu, Kai,Ban, Yong-Liang,Wang, Xue-Yang,Wu, Li-Zhu,Liu, Qiang
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supporting information
p. 885 - 889
(2019/02/14)
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- Electrochemical oxidative cyclization of olefinic carbonyls with diselenides
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The tandem cyclization of olefinic carbonyls with easily accessible diselenides facilitated by electrochemical oxidation has been successfully developed, which provides an environmentally friendly method for the construction of C-Se and C-O bonds simultaneously. A series of seleno dihydrofurans and seleno oxazolines, bearing fragile heterocycles, subtle C-I bonds and supernumerary vinyl groups, were forged using this elegant chelation strategy. Neither metal catalysts nor external chemical oxidants are required to promote this transformation.
- Guan, Zhipeng,Wang, Yunkun,Wang, Huamin,Huang, Yange,Wang, Siyuan,Tang, Hongding,Zhang, Heng,Lei, Aiwen
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supporting information
p. 4976 - 4980
(2019/09/30)
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- Silver-Promoted Synthesis of 5-[(Pentafluorosulfanyl)methyl]-2-oxazolines
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The synthesis of 5-[(pentafluorosulfanyl)methyl]-2-oxazolines is reported. The use of a silver promoter allows the intramolecular cyclization of N-[2-chloro-3-(pentafluorosulfanyl)propyl]amide to occur without elimination of the chlorine atom, a reaction
- Gilbert, Audrey,Bertrand, Xavier,Paquin, Jean-Fran?ois
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supporting information
p. 7257 - 7260
(2018/11/23)
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- Chromium-Catalyzed Asymmetric Dearomatization-Addition Reactions of Halomethyloxazoles and Indoles
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The asymmetric dearomatization-addition reaction of halomethyloxazoles and halomethylindoles with aldehydes is realized in the presence of a carbazole-based bisoxazoline CrCl 2 complex to afford the corresponding enantioenriched, hydroxylated oxazoline and indoline products. The observed excellent chemo-, regio-, diastereo- and enantioselectivities are notable advantages of this protocol. The strategy established in this study is expected to find application in the synthesis of azaheterocycles with biological significance and useful functionalities.
- Wang, Zheng,Ji, Hongtao,He, Wei-Min,Xiong, Yang,Zhang, Guozhu
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supporting information
p. 4915 - 4921
(2018/06/08)
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- One-Pot Amide Bond Formation from Aldehydes and Amines via a Photoorganocatalytic Activation of Aldehydes
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A mild, one-pot, and environmentally friendly synthesis of amides from aldehydes and amines is described. Initially, a photoorganocatalytic reaction of aldehydes with di-isopropyl azodicarboxylate leads to an intermediate carbonyl imide, which can react with a variety of amines to afford the desired amides. The initial visible light-mediated activation of a variety of monosubstituted or disubstituted aldehydes is usually fast, occurring in a few hours. Following the photocatalytic reaction, addition of the primary amine at room temperature or the secondary amine at elevated temperatures leads to the corresponding amide from moderate to excellent yields without epimerization. This methodology was applied in the synthesis of Moclobemide, a drug against depression and social anxiety.
- Papadopoulos, Giorgos N.,Kokotos, Christoforos G.
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p. 7023 - 7028
(2016/08/30)
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- Copper-Catalyzed Divergent Trifluoromethylation/Cyclization of Unactivated Alkenes
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Most of the precedent copper-catalyzed trifluoromethylation reactions of unactivated alkenes concern terminal alkenes, and these processes are terminated in elimination, or nucleophilic addition, or semipinacol rearrangement, or C-H bond functionalization steps. In this study, we develop a trifluoromethylation method for both unactivated terminal and internal alkenes to enable divergent late-stage radical cyclization and achieve high molecular complexity. These cyclizations are well consistent with Baldwin's rule. Furthermore, a kinetic isotope effect (KIE) study and control reactions were conducted, and a plausible mechanism is proposed.
- Zheng, Jing,Deng, Ziyang,Zhang, Yan,Cui, Sunliang
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p. 746 - 751
(2016/03/09)
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- Iodine(III)-promoted synthesis of oxazolines from N-allylamides
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PhI(OAc)2 (activated by BF3·OEt2) has been used to promote the oxidative cyclization of N-allylamides to give oxazolines. The reaction products are formed in high yield and, when a branched allylic amine is used, high diastereoselectivity. Initial mechanistic experiments suggest that the final C-O bond is formed from a reactive tight ion pair, rather than a neutral external nucleophile.
- Moon, Nicholas G.,Harned, Andrew M.
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supporting information
p. 2960 - 2963
(2013/06/27)
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