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Yong Tang - One of the best experts on this subject based on the ideXlab platform.
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A Tandem Intramolecular Michael Addition/Wittig Reaction for the Synthesis of Fused Cyclohexadiene Derivatives†
Chinese Journal of Chemistry, 2010Co-Authors: Qinggang Wang, Xiu-li Sun, Jun-cheng Zheng, Yong TangAbstract:A tandem intramolecular Michael addition/Wittig reaction has been developed for the synthesis of fused Cyclohexadiene derivatives from phosphonium salt 3. This annulation reaction affords the Cyclohexadienes in moderate to excellent yields, depending on the substrates. A mechanism is proposed to account for the tandem process.
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a tandem intramolecular michael addition wittig reaction for the synthesis of fused Cyclohexadiene derivatives
Chinese Journal of Chemistry, 2010Co-Authors: Qinggang Wang, Xiu-li Sun, Jun-cheng Zheng, Yong TangAbstract:A tandem intramolecular Michael addition/Wittig reaction has been developed for the synthesis of fused Cyclohexadiene derivatives from phosphonium salt 3. This annulation reaction affords the Cyclohexadienes in moderate to excellent yields, depending on the substrates. A mechanism is proposed to account for the tandem process.
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tandem michael addition ylide olefination reaction for the synthesis of highly functionalized Cyclohexadiene derivatives
Tetrahedron, 2008Co-Authors: Xun Han, Xiu-li Sun, Yong TangAbstract:A tandem Michael addition/ylide olefination for the rapid creation of highly functionalized Cyclohexadiene is developed. The tandem annulation reactions afford versatile Cyclohexadienes in good to excellent isolated yields. This method has been successfully applied to the synthesis of three biologically active molecules.
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Tandem Michael addition/ylide olefination reaction for the synthesis of highly functionalized Cyclohexadiene derivatives
Tetrahedron, 2008Co-Authors: Xun Han, Xiu-li Sun, Yong TangAbstract:A tandem Michael addition/ylide olefination for the rapid creation of highly functionalized Cyclohexadiene is developed. The tandem annulation reactions afford versatile Cyclohexadienes in good to excellent isolated yields. This method has been successfully applied to the synthesis of three biologically active molecules.
Xiu-li Sun - One of the best experts on this subject based on the ideXlab platform.
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A Tandem Intramolecular Michael Addition/Wittig Reaction for the Synthesis of Fused Cyclohexadiene Derivatives†
Chinese Journal of Chemistry, 2010Co-Authors: Qinggang Wang, Xiu-li Sun, Jun-cheng Zheng, Yong TangAbstract:A tandem intramolecular Michael addition/Wittig reaction has been developed for the synthesis of fused Cyclohexadiene derivatives from phosphonium salt 3. This annulation reaction affords the Cyclohexadienes in moderate to excellent yields, depending on the substrates. A mechanism is proposed to account for the tandem process.
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a tandem intramolecular michael addition wittig reaction for the synthesis of fused Cyclohexadiene derivatives
Chinese Journal of Chemistry, 2010Co-Authors: Qinggang Wang, Xiu-li Sun, Jun-cheng Zheng, Yong TangAbstract:A tandem intramolecular Michael addition/Wittig reaction has been developed for the synthesis of fused Cyclohexadiene derivatives from phosphonium salt 3. This annulation reaction affords the Cyclohexadienes in moderate to excellent yields, depending on the substrates. A mechanism is proposed to account for the tandem process.
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tandem michael addition ylide olefination reaction for the synthesis of highly functionalized Cyclohexadiene derivatives
Tetrahedron, 2008Co-Authors: Xun Han, Xiu-li Sun, Yong TangAbstract:A tandem Michael addition/ylide olefination for the rapid creation of highly functionalized Cyclohexadiene is developed. The tandem annulation reactions afford versatile Cyclohexadienes in good to excellent isolated yields. This method has been successfully applied to the synthesis of three biologically active molecules.
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Tandem Michael addition/ylide olefination reaction for the synthesis of highly functionalized Cyclohexadiene derivatives
Tetrahedron, 2008Co-Authors: Xun Han, Xiu-li Sun, Yong TangAbstract:A tandem Michael addition/ylide olefination for the rapid creation of highly functionalized Cyclohexadiene is developed. The tandem annulation reactions afford versatile Cyclohexadienes in good to excellent isolated yields. This method has been successfully applied to the synthesis of three biologically active molecules.
Armido Studer - One of the best experts on this subject based on the ideXlab platform.
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stereospecific palladium catalyzed decarboxylative c sp3 c sp2 coupling of 2 5 Cyclohexadiene 1 carboxylic acid derivatives with aryl iodides
ChemInform, 2012Co-Authors: Chihming Chou, Indranil Chatterjee, Armido StuderAbstract:Palladium-catalyzed decarboxylative arylation of 2,5-Cyclohexadiene-1-carboxylic acids (I) with aryl iodides proceeds smoothly to give 5-arylated 1,3-Cyclohexadienes (III) in good yields.
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evolution of functional Cyclohexadiene based synthetic reagents the importance of becoming aromatic
Accounts of Chemical Research, 2005Co-Authors: John C. Walton, Armido StuderAbstract:Suites of new precursors designed around a Cyclohexadiene core and intended to mediate “clean” radical chain syntheses have been prepared and tested. 1-Functionalized cyclohexa-2,5-dienes were found to readily donate H-atoms, and the resulting cyclohexadienyl radicals rapidly extruded their functional group as a free radical, because this β-scission restored aromaticity to the ring. This concept was employed to generate designer radicals from esters of the corresponding alcohols with 1-methyl- or 1-phenylcyclohexa-2,5-diene-1-carboxylic acids. In a similar way, pre-adapted carbamoyl radicals were obtained from cyclohexadienyl-amides and proved advantageous for syntheses of α- and β-lactams. Oxime ether substituted carbamoyl radicals cyclized successfully in convenient syntheses of dihydroindolin-2-ones with N-functionality at the 3-position. Similarly, silicon-centered radicals were obtained from 1-silylated Cyclohexadienes, and these reagents proved to be very efficient, environmentally benign organotin ...
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Desymmetrization and Diastereotopic Group Selection in 1,4-Cyclohexadienes
Synlett, 2005Co-Authors: Armido Studer, Florian SchlethAbstract:Diastereotopic group selection in 1,4-Cyclohexadienes is a useful approach to synthesize rather complex compounds in a single operation. The stereoinduction occurs via a covalently bound stereogenic center. Cycloadditions, Michael additions, and radical reactions have been conducted as group-selective processes. Even more elegant is the desymmetrization of an achiral 1,4-Cyclohexadiene. Various chiral reagents have been used successfully to desymmetrize 1,4-Cyclohexadienes. In one step, at least two new stereogenic centers are formed. Chiral quaternary carbon centers can he obtained with high selectivity. This Account will provide an overview on diastereotopic group selection and desymmetrization in various 1,4-Cyclohexadiene derivatives.
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Silylated Cyclohexadienes as new radical chain reducing reagents: preparative and mechanistic aspects.
Journal of the American Chemical Society, 2003Co-Authors: Armido Studer, Stephan Amrein, Florian Schleth, Tobias Schulte, John C. WaltonAbstract:Various silylated 1,4-Cyclohexadienes are presented as superior tin hydride substitutes for the conduction of various radical chain reductions. Debrominations, deiodinations, and deselenations can be performed using these environmentally benign reagents. Furthermore, Barton-McCombie-type deoxygenations using silylated Cyclohexadienes are described. Radical cyclizations, ring expansions, and Giese-type addition reactions with the new tin hydride substitutes are presented. The polymerization of styrene can be regulated using silylated Cyclohexadienes. Rate constants for hydrogen atom abstraction from two 1-silyl-Cyclohexadienes by primary C-radicals were determined. The effects of the Cyclohexadiene substituents on the reaction outcomes are discussed. Finally, qualitative EPR experiments on silyl radical expulsion from silylated cyclohexadienyl radicals are presented.
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Radical transfer hydrosilylation/cyclization using silylated Cyclohexadienes.
Organic letters, 2001Co-Authors: Stephan Amrein, And Andreas Timmermann, Armido StuderAbstract:A new method for mild metal-free hydrosilylation is described. Silylated Cyclohexadienes are used as radical transfer hydrosilylating reagents for various double and triple bonds. A trialkylsilane is transferred from a Cyclohexadiene moiety to an alkene. The hydrosilylation can be combined with a C−C bond formation as shown for the preparation of silylated cycloalkanes from the corresponding dienes.
Michael L. Mckee - One of the best experts on this subject based on the ideXlab platform.
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Reactions of 1,3-Cyclohexadiene with singlet oxygen. A theoretical study.
Journal of the American Chemical Society, 2001Co-Authors: And Fatma Sevin, Michael L. MckeeAbstract:A thorough study of the reaction of singlet oxygen with 1,3-Cyclohexadiene has been made at the B3LYP/6-31G(d) and CASPT2(12e,10o) levels. The initial addition reaction follows a stepwise diradical pathway to form Cyclohexadiene endoperoxide with an activation barrier of 6.5 kcal/mol (standard level = CASPT2(12e,10o)/6-31G(d); geometries and zero-point corrections at B3LYP/6-31G(d)), which is consistent with an experimental value of 5.5 kcal/mol. However, as the enthalpy of the transition structure for the second step is lower than the diradical intermediate, the reaction might also be viewed as a nonsynchronous concerted reaction. In fact, the concertedness of the reaction is temperature dependent since entropy differences create a free energy barrier for the second step of 1.8 kcal/mol at 298 K. There are two ene reactions; one is a concerted mechanism (ΔH‡ = 8.8 kcal/mol) to 1-hydroperoxy-2,5-Cyclohexadiene (5), while the other, which forms 1-hydroperoxy-2,4-Cyclohexadiene (18), passes through the same...
B. François - One of the best experts on this subject based on the ideXlab platform.
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Synthesis and characterization of star copolymers consisting of fullerene and conjugated polyphenylene: 6-star-C60[styrene-poly(1,4-phenylene)-block-polystyrene] and 6-star-C60[polystyrene-block-poly(1,4-phenylene)]
Macromolecules, 2002Co-Authors: E. Mignard, R.c. Hiorns, B. FrançoisAbstract:The grafting of "living" polystyrene-block-poly(1,3-Cyclohexadiene)-block-styryllithium and poly(1,3-cylclohexadiene)-block-polystyryllithium onto C60 yielded, respectively, 6-star-fullerene[styrene-block-poly(1,3-Cyclohexadiene)-block-polystyrene] and 6-star-fullerene[polystyrene-block-poly(1,3-Cyclohexadiene)]. Selective dehydrogenation of these macromolecules yielded, respectively, 6-star-fullerene-[styrene-block-poly(1,4-phenylene)-block-polystyrene], C60(st-PPP-PS)6, and 6-star-fullerene[polystyrene-block-poly(1,4-phenylene)], C60(PS-PPP)6. 6-star-Fullerene[poly(1,4-phenylene)-block-polystyrene] could not be synthesized via this route as fullerene-poly(1,3-Cyclohexadiene) bonds were found to form without control and to degrade during aromatization. Star copolymers containing conjugated PPP were characterized by size exclusion chromatography, UV, and fluorescence spectroscopy. Fluorescence quantum yields of C60(st-PPP-PS)6 and C60(PS-PPP)6 in THF were compared and discussed in light of characterizations of PPP-PS-PPP in comparable conditions without or mixed with C60(PS)6.
