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Youqian Deng - One of the best experts on this subject based on the ideXlab platform.
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pdi2 catalyzed coupling cyclization reactions involving two different 2 3 allenols an efficient synthesis of 4 1 3 dien 2 yl 2 5 Dihydrofuran derivatives
Chemistry: A European Journal, 2008Co-Authors: Youqian DengAbstract:Transition-metal-catalyzed dimeric coupling-cyclization reactions of two different 2,3-allenols afforded 4-(1',3'-dien-2'-yl)-2,5-Dihydrofuran derivatives 3. 2-Substituted 2,3-allenols 1 cyclized to form the 2,5-Dihydrofuran ring, whereas the 2-unsubstituted 2,3-allenols 2 provided the 1,3-diene unit at the 4-position. The reaction is proposed to proceed through an oxypalladation, insertion, and beta-hydroxide elimination process. The C=C double bond was formed with high E stereoselectivity by beta-hydroxide elimination.
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pdcl2 nai catalyzed homodimeric coupling cyclization reaction of 2 3 allenols an efficient synthesis of 4 1 3 dien 2 yl 2 5 Dihydrofuran derivatives
Journal of Organic Chemistry, 2008Co-Authors: Youqian DengAbstract:A PdCl2/NaI-catalyzed homodimeric coupling-cyclization reaction of 2,3-allenols was observed to provide an efficient route to 4-(1‘,3‘-dien-2‘-yl)-2,5-Dihydrofuran derivatives. By using the easily available optically active starting materials, 2,5-Dihydrofurans with high enantiopurity may be prepared. A Pd(II)-catalyzed mechanism was also discussed.
Patrick J. Guiry - One of the best experts on this subject based on the ideXlab platform.
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Synthesis of Dihydrofurans Substituted in the 2‐Position
European Journal of Organic Chemistry, 2005Co-Authors: Timothy G. Kilroy, Timothy P. O'sullivan, Patrick J. GuiryAbstract:Many natural products and biologically active compounds contain the Dihydrofuran subunit. Molecules incorporating either 2-substituted, 2,2-disubstituted 2,3- or 2,5-Dihydrofurans are widespread in the literature and represent key “molecular building blocks”. The preparation of substituted Dihydrofurans remains a current challenge in organic synthesis and this microreview details the various routes employed for their synthesis in the literature to the end of 2004. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
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The Application of HETPHOX Ligands to the Asymmetric Intermolecular Heck Reaction of 2,3-Dihydrofuran and 2,2-Disubstituted-2,3-Dihydrofurans
Synthesis, 2004Co-Authors: Tim G. Kilroy, Pier Giorgio Cozzi, Nicole End, Patrick J. GuiryAbstract:A series of thiophene- and benzothiophene-oxazoline containing ligands, were applied in the intermolecular asymmetric phenylation and cyclohexenylation of 2,3-Dihydrofuran 1. Phenylation proceeded in moderate to high chemical yields, with good regioselectivities and in up to 95% ee. Cyclohexenylations gave similarly high chemical yields and regioselectivities with the optimal result being a 96% yield of the major product in 97% ee. 2,2-Dialkyl-2,3-Dihydrofurans were also tested as substrates and the phenylation and cyclohexenylation of 2,2-dimethyl-2,3-Dihydrofuran proceeded in high yields and ee's up to 91% and 89%, respectively. The phenylation and cyclohexenylation of the 2,2-diethyl analogue proceeded in excellent yields and ee's up to 99% and 87%, respectively. For each substrate, palladium complexes formed from the t-butyl-substituted ligand 10 gave the highest yields, regioselectivities, and enantioselectivities over the broad range of reaction conditions studied. 2,2-Diisopropyl-2,3-Dihydrofuran was prepared but was found to be unreactive in the intermolecular Heck reaction thus providing insight into to the steric limits for 2,3-Dihydrofuran substrates.
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From 2,3-Dihydrofuran to 2,2-dialkyl-2,3-Dihydrofurans: new substrates for the intermolecular asymmetric Heck reaction
Journal of Molecular Catalysis A-chemical, 2002Co-Authors: Tim G. Kilroy, Alan J. Hennessy, David J. Connolly, Yvonne M. Malone, Annette Farrell, Patrick J. GuiryAbstract:Palladium complexes of heterobidentate ferrocene-containing ligands were tested as catalysts in asymmetric intermolecular Heck reactions employing 2,3-Dihydrofuran as the substrate and afforded a mixture of products in various ratios depending on the choice of ligand and the conditions employed. The favoured kinetic isomer was obtained in enantioselectivities of up to 99%. Dihydrofurans disubstituted at the 2-position were postulated as new substrates as they form a single regioisomeric product, thus providing a true comparative test of enantioselectivity of a range of palladium complexes. The synthesis of 2,2-dimethyl-2,3-Dihydrofuran and 2,2-diethyl-2,3-Dihydrofuran and their application in the intermolecular asymmetric Heck reaction with both diphosphine and phosphinamine ligands is also described. For both phenylation and cyclohexenylation of 2,3-Dihydrofuran and 2,2-dimethyl-2,3-Dihydrofuran the t-Bu substituted diphenylphosphinoferrocenyloxazoline ligand gave best results. The use of 2,2-diethyl-2,3-Dihydrofuran as substrate demonstrated that the increased bulk at the 2-position had a deleterious effect on both the chemical yields and ees in phenylations and cyclohexenylations although enantioselectivities of 94 and 93% were obtained, respectively.
Mehmet Yilmaz - One of the best experts on this subject based on the ideXlab platform.
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Regioselective radical addition of 3-oxopropanenitriles with terminal dienes promoted by cerium(IV) ammonium nitrate and manganese(III) acetate
2019Co-Authors: Bahadir Hocaoglu, Mehmet YilmazAbstract:Radical addition of 3-oxopropanenitriles to 1,3-butadiene derivatives promoted by (NH4)2Ce(NO2)6 and Mn(OAc)3 afforded 5-ethenyl-4,5-Dihydrofuran-3-carbonitriles in low to good yields. These Dihydrofurans were characterised by IR, 1H-NMR, 13C-NMR and HRMS spectra. All radical additions performed via CAN and Mn(OAc)3 were occurred on the terminal double bond on dienes. A mechanism for the formation of the Dihydrofurans was proposed.
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radical cyclization of fluorinated 1 3 dicarbonyl compounds with dienes using manganese iii acetate and synthesis of fluoroacylated 4 5 Dihydrofurans
Helvetica Chimica Acta, 2011Co-Authors: Mehmet Yilmaz, Vildan Burgaz E Yilmaz, Tarik A PekelAbstract:Radical cyclizations of fluorinated 1,3-dicarbonyl compounds with dienes mediated by Mn(OAc)3 afforded 4,5-Dihydrofurans containing difluoroacetyl, trifluoroacetyl, or heptafluorobutanoyl groups in good-to-excellent yields. Additionally, 2-(difluoromethyl)-4,5-Dihydrofurans and a 4,7-dihydrooxepin derivative were obtained as unexpected products in the reaction of 4,4-difluoro-1-phenylbutane-1,3-dione with 1,3-diphenylbuta-1,3-diene. The radical cyclization of symmetrical dienes such as 2,3-dimethylbuta-1,3-diene and 1,4-diphenylbuta-1,3-diene with 1,3-diketones furnished the corresponding products in low yields. However, treatment of 1-phenylbuta-1,3-diene with 1,3-dicarbonyl compounds afforded 4,5-Dihydrofurans containing fluoroacyl groups. The radical cyclizations with 3-methyl-1-phenylbuta-1,3-diene and 1,3-diphenylbuta-1,3-diene led to 4,5-Dihydrofurans in good yields, since Me and Ph groups at C(3) of these dienes increase the stability of the radical intermediate.
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oxidative cyclization of 3 oxopropanenitriles with α β unsaturated amides by manganese iii acetate regio and stereoselective synthesis of 4 cyano 2 3 Dihydrofuran 3 carboxamides
Tetrahedron, 2007Co-Authors: Vildan E Burgaz, Tarik A Pekel, Mehmet Yilmaz, Atilla OktemerAbstract:Abstract 4-Cyano-2,3-Dihydrofuran-3-carboxamides were obtained from the oxidative cyclization of 3-oxopropanenitriles with unsaturated amides using manganese(III) acetate. Treatment of 3-oxopropanenitriles with (2E)-3-(5-methyl-2-furyl)acrylamide and (2E)-3-(2-thienyl)acrylamide gave 2-(5-methyl-2-furyl) and 2-(2-thienyl) substituted 4-cyano-2,3-Dihydrofuran-3-carboxamides in moderate yields, respectively. However, (2E)-3-(2-furyl)acrylamide and (2E)-3-phenylacrylamide did not produce any product under the same conditions. On the other hand, reaction of a dienamide such as (2E,4E)-5-phenylpenta-2,4-dienamide with 3-oxopropanenitriles gave diastereomeric mixtures of 2-(2-vinylphenyl)-4-cyano-2,3-Dihydrofuran-3-carboxamides. Mechanisms are proposed for the formation of all of these compounds.
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Manganese(III) acetate mediated synthesis of 3-trifluoroacetyl-4,5-Dihydrofurans and 3-(Dihydrofuran-2(3H)-ylidene)-1,1,1-trifluoroacetones by free radical cyclization. Part 1
Journal of Fluorine Chemistry, 2005Co-Authors: Mehmet Yilmaz, A. Tarık PekelAbstract:Abstract 2-Trifluoroacetyl-4,5-Dihydrofurans were obtained by manganese(III) acetate mediated radical cyclization of trifluoromethyl-1,3-dicarbonyl compounds ( 1a – c ) with conjugated alkenes ( 2a – h ). The reaction of 1,1,1-trifluoropentane-2,4-dione ( 1a ) with propenylbenzene and 1,1-diphenyl-1-butene surprisingly yielded 3-(Dihydrofuran-2(3H)-ylidene)-1,1,1-trifluoroacetones besides 3-trifluoroacetyl-4,5-Dihydrofurans.
Mark D. Symes - One of the best experts on this subject based on the ideXlab platform.
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Towards a better understanding of the electrosynthesis of 2,5-dicarboxy-2,5-Dihydrofurans: structure, mechanism and influence over stereochemistry
Royal Society open science, 2019Co-Authors: Michael A. Shipman, Stephen Sproules, Claire Wilson, Mark D. SymesAbstract:2,5-Dicarboxy-2,5-Dihydrofurans are key constituents of a number of natural products and have roles as intermediates in the formation of other such compounds of interest. Typically, these species are synthesized using toxic Pb(IV) salts. Electrochemical syntheses of 2,5-diacetoxy-2,5-Dihydrofuran that do not require the use of lead have been reported, but a general lack of experimental detail has prevented these procedures from being more widely adopted. Moreover, no electrochemical study has yet reported the ratio of cis and trans isomers produced. Herein, we compare the chemical, lead-based route to 2,5-diacetoxy-2,5-Dihydrofuran with a fully described electrosynthesis method. In doing so, we have discovered that the cis and trans isomers of this compound were previously incorrectly assigned in the literature, an error that we correct by obtaining the crystal structure of cis-2,5-diacetoxy-2,5-Dihydrofuran. This allows the ratios of the isomers as prepared by the chemical (2 : 1 cis : trans) and electrochemical (7 : 5 cis : trans) methods to be obtained. Through experimental and computational insights, we propose a mechanism for the electrochemical synthesis of 2,5-dicarboxy-2,5-Dihydrofurans and go some way towards validating this mechanism by synthesizing 2,5-dibutoxy-2,5-Dihydrofuran electrochemically for the first time. We hope that these findings will provide some greater clarity to the literature surrounding the electrosynthesis and potential applications of 2,5-dicarboxy-2,5-Dihydrofurans.
Gözde Ulas - One of the best experts on this subject based on the ideXlab platform.
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Kishner's Reduction of 2-Furylhydrazone Gives 2-Methylene-2,3-Dihydrofuran, a Highly Reactive Ene in the Ene Reaction
The Journal of organic chemistry, 2005Co-Authors: William H. Miles, Elizabeth A. Dethoff, Hannah H. Tuson, Gözde UlasAbstract:The Kishner reduction of 2-furylhydrazone gives 2-methylene-2,3-Dihydrofuran as the major abnormal reduction product. 2-Methylene-2,3-Dihydrofuran is an excellent ene in the carbonyl-ene reaction, reacting with a variety of aldehydes. Most notable was the asymmetric carbonyl-ene reaction of 2-methylene-2,3-Dihydrofuran and decanal using Ti(OCH(CH3)2)4/(S)-BINOL to give the corresponding alcohol in 66% yield and 94% ee. The reaction of 2-methylene-2,3-Dihydrofuran with 2 equiv of 1,4-benzoquinone unexpectedly gave a monoalkylated 1,4-hydroquinone/1,4-benzoquinone electron donor−acceptor complex.