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Krishnamoorthy Rajagopalan - One of the best experts on this subject based on the ideXlab platform.
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Studies in Base‐Catalyzed Allenic Oxy‐Cope Rearrangement: An Expedient Synthesis of Functionalized Bicyclo(4.3.0)‐ and ‐(4.4.0)Systems and 3, 5‐Cycloundecadien‐1‐one.
ChemInform, 2010Co-Authors: A. Balakumar, S. Janardhanam, Krishnamoorthy RajagopalanAbstract:The base-catalyzed Oxy-Cope Rearrangement of systems incorporating an allenic π system was studied. The Rearrangement incidentally leads to functionalized bicyclo[4.3.0]nonane 15, bicyclo[4.4.0]decanes 6 and 10, and 3,5-cycloundecadien-1-one 20. The effect of ring size and nature of the base on the Rearrangement was also studied
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Synthesis of Linearly Fused Tricyclic Compounds via Thermal Oxy-Cope Rearrangement.
ChemInform, 2010Co-Authors: P. Shanmugam, Krishnamoorthy RajagopalanAbstract:Abstract Linearly fused tricyclic [5.6.5] and [6.6.6] compounds 4, 6, 10 and 12 were prepared from ethynyl and allenyl derivatives of self condensed cycloalkanones 3, 5, 9 and 11 by thermal Oxy-Cope Rearrangement is described.
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Optically active functionalised hydrazulenoid skeleton - via Oxy-Cope Rearrangement
Tetrahedron Letters, 1998Co-Authors: Rajagopal Srinivasan, Krishnamoorthy RajagopalanAbstract:Abstract Ethynyl alcohol 4 was synthesised from (1)-menthone by the reaction sequence-hydroxyformylation, C-methylation, Wittig-olefination and addition of lithium acetylide to CO. The concerted thermally allowed Oxy-Cope Rearrangement of the optically active substrate 4 is reported.
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STUDIES IN BROMOACETYLENIC Oxy-Cope Rearrangement : SYNTHESIS OF FUNCTIONALISED MEDIUM-SIZE, BICYCLIC AND ANGULARLY FUSED TRICYCLIC COMPOUNDS
Tetrahedron, 1997Co-Authors: P. Shanmugam, Balachari Devan, Rajagopal Srinivasan, Krishnamoorthy RajagopalanAbstract:Abstract Functionalised title compounds 4, 7, 11, 12 and 16 were synthesised from bromoethynyl derivatives of cycloalkanes 2, 6 , Wieland-Meisher ketone 10 and spiro[5.5] ketone 15 by anionic and thermal Oxy-Cope Rearrangement is described.
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Synthesis of Functionalized BICYCLIC [4.3.0],[4.4.0] Compounds via Base-Catalysed Oxy-Cope Rearrangement
Synthetic Communications, 1996Co-Authors: P. Shanmugam, Krishnamoorthy RajagopalanAbstract:Abstract A general method of synthesising functionalized title compounds via Oxy-Cope Rearrangement using sodium ethoxide is reported.
Wai-man Lee - One of the best experts on this subject based on the ideXlab platform.
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Synthetic Applications (I) of the Tandem [2,3]-Wittig-Anionic Oxy-Cope Rearrangement: Stereoselective Disubstituted Tetrahydropyran Synthesis by Electrophile Initiated Cyclisation
Tetrahedron Letters, 1997Co-Authors: Nicholas Greeves, Wai-man LeeAbstract:Abstract Reduction of the δ,e-unsaturated aldehydes produced by tandem [2,3]-Wittig-anionic Oxy-Cope Rearrangement followed by stereoselective electrophilic cyclisation and reductive removal of the electrophile leads to single diastereoisomers of tetrahydropyrans. © 1997 Elsevier Science Ltd.
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Synthetic Applications (II) of the Tandem [2,3]-Wittig-Anionic Oxy-Cope Rearrangement: Stereoselective Trisubstituted δ-Lactone and Tetrahydropyran Synthesis
Tetrahedron Letters, 1997Co-Authors: Nicholas Greeves, Wai-man Lee, Jim BarkleyAbstract:Abstract Di- and trisubstituted δ-lactones have been prepared by stereoselective iodolactonisation and phenylselenolactonisation of δ,e-unsaturated carboxylic acids. The acyclic stereochemistry of the acids arises from highly stereoselective tandem [2,3]-Wittig-anionic Oxy-Cope Rearrangement of cinnamyl ethers with potassium hydride and 18-crown-6 in THF to give δ,e-unsaturated aldehydes. © 1997 Elsevier Science Ltd.
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Stereoselective [2,3]-Wittig and Tandem [2,3]-Wittig-Anionic Oxy-Cope Rearrangements of Bis-allylic Ethers : Effect of Substituents
Tetrahedron Letters, 1997Co-Authors: Nicholas Greeves, Wai-man LeeAbstract:Abstract Acyclic bis-allylic ethers undergo, syn or anti stereoselective [2,3]-Wittig Rearrangement to give homoallylic alcohols depending on the substituents, and E -selective tandem [2,3]-Wittig-anionic Oxy-Cope Rearrangement to give δ,e-unsaturated aldehydes. © 1997 Elsevier Science Ltd.
Nicholas Greeves - One of the best experts on this subject based on the ideXlab platform.
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Synthetic Applications (I) of the Tandem [2,3]-Wittig-Anionic Oxy-Cope Rearrangement: Stereoselective Disubstituted Tetrahydropyran Synthesis by Electrophile Initiated Cyclisation
Tetrahedron Letters, 1997Co-Authors: Nicholas Greeves, Wai-man LeeAbstract:Abstract Reduction of the δ,e-unsaturated aldehydes produced by tandem [2,3]-Wittig-anionic Oxy-Cope Rearrangement followed by stereoselective electrophilic cyclisation and reductive removal of the electrophile leads to single diastereoisomers of tetrahydropyrans. © 1997 Elsevier Science Ltd.
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Synthetic Applications (II) of the Tandem [2,3]-Wittig-Anionic Oxy-Cope Rearrangement: Stereoselective Trisubstituted δ-Lactone and Tetrahydropyran Synthesis
Tetrahedron Letters, 1997Co-Authors: Nicholas Greeves, Wai-man Lee, Jim BarkleyAbstract:Abstract Di- and trisubstituted δ-lactones have been prepared by stereoselective iodolactonisation and phenylselenolactonisation of δ,e-unsaturated carboxylic acids. The acyclic stereochemistry of the acids arises from highly stereoselective tandem [2,3]-Wittig-anionic Oxy-Cope Rearrangement of cinnamyl ethers with potassium hydride and 18-crown-6 in THF to give δ,e-unsaturated aldehydes. © 1997 Elsevier Science Ltd.
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Stereoselective [2,3]-Wittig and Tandem [2,3]-Wittig-Anionic Oxy-Cope Rearrangements of Bis-allylic Ethers : Effect of Substituents
Tetrahedron Letters, 1997Co-Authors: Nicholas Greeves, Wai-man LeeAbstract:Abstract Acyclic bis-allylic ethers undergo, syn or anti stereoselective [2,3]-Wittig Rearrangement to give homoallylic alcohols depending on the substituents, and E -selective tandem [2,3]-Wittig-anionic Oxy-Cope Rearrangement to give δ,e-unsaturated aldehydes. © 1997 Elsevier Science Ltd.
Leo A. Paquette - One of the best experts on this subject based on the ideXlab platform.
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The First Thermally-Induced Retro-Oxy-Cope Rearrangement.
ChemInform, 2010Co-Authors: Steven W. Elmore, Leo A. PaquetteAbstract:Abstract The reversibility of the thermal Oxy-Cope Rearrangement is demonstrated with the specific example , and the pathway and energetics associated with this phenomenon are outlined.
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Relevance of Oxyanion Stereochemistry to Chirality Transfer in Anionic Oxy‐Cope Rearrangements.
ChemInform, 2010Co-Authors: Leo A. Paquette, George D. MaynardAbstract:Geometrically and optically pure (3R,5E)- and (3R,5Z)-1,5-heptadien-3-ols undergo anionic Oxy-Cope Rearrangement under the exclusice control of oxyanion orientation with a 58-64% preference for equatorial oxygen. Six semicyclic dienols have also been synthesized where the preferred oxyanion-driven sigmatropic Rearrangement pathway is obligatorily pitted against π-facial biases offered by 4-tert-butylcyclohexenyl, norbornenyl, and camphenyl rings. These Rearrangements therefore offer especially stringent tests of those factors that control the level and direction of chirality transfer. The data show the oxyanion to disfavor becoming involved in 1,3-diaxial relationships
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Stereoselective Construction of the Dicyclopenta(a,d)cyclooctene Core of the Ceroplastin Sesterterpenes by Way of the Anionic Oxy‐Cope Rearrangement.
ChemInform, 2010Co-Authors: Leo A. Paquette, Shaowo Liang, Hailong WangAbstract:Bicyclo[3.2.1]octanediones such as 9, which are readily available by double carbonylation of (1,3-cyclohexadiene)iron tricarbonyl complexes according to Eilbracht, are amenable to regiospecific methylenation under Wittig conditions. Reduction of 10 with copper hydride leads to 11, which can be resolved by application of Johnson's sulfoximine technology and oxidized to give the enantiopure antipodes of 10. Variously substituted cyclopentenyl anions undergo 1,2-addition to 10, providing carbinols which are capable of anionic Oxy-Cope Rearrangement via chair transition states. These structural reorganizations are fully stereocontrolled and lead directly to functionalized dicyclopenta[a,d]cyclooctenes. When 11 is treated analogously, only [1,3] sigmatropy is observed and inversion of stereochemistry at the migrating carbon prevails. Both processes exhibit impressive scaffolding powers and are characterized by brevity.
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synthetic studies on spinosyn a convenient enantioselective construction of a suitably functionalized trans anti cis decahydro as indacene intermediate via 3 3 sigmatropy and double configurational inversion
ChemInform, 1997Co-Authors: Leo A. Paquette, Zhongli Gao, Graham SmithAbstract:Abstract An enantioselective route to the decahydro-as-indacene15 is described. Anionic Oxy-Cope Rearrangement of alcohol 5 initiates the sequence, which capitalizes on thermodynamics to control ultimate elaboration of the four key stereogenic centers resident in the several intermediates.
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Stereoselective Construction of the Dicyclopenta[a,d]cyclooctene Core of the Ceroplastin Sesterterpenes by Way of the Anionic Oxy-Cope Rearrangement
The Journal of Organic Chemistry, 1996Co-Authors: Leo A. Paquette, Shaowo Liang, Hailong WangAbstract:Bicyclo[3.2.1]octanediones such as 9, which are readily available by double carbonylation of (1,3-cyclohexadiene)iron tricarbonyl complexes according to Eilbracht, are amenable to regiospecific methylenation under Wittig conditions. Reduction of 10 with copper hydride leads to 11, which can be resolved by application of Johnson's sulfoximine technology and oxidized to give the enantiopure antipodes of 10. Variously substituted cyclopentenyl anions undergo 1,2-addition to 10, providing carbinols which are capable of anionic Oxy-Cope Rearrangement via chair transition states. These structural reorganizations are fully stereocontrolled and lead directly to functionalized dicyclopenta[a,d]cyclooctenes. When 11 is treated analogously, only [1,3] sigmatropy is observed and inversion of stereochemistry at the migrating carbon prevails. Both processes exhibit impressive scaffolding powers and are characterized by brevity.
Martin Hiersemann - One of the best experts on this subject based on the ideXlab platform.
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Sequencing Pericyclic Reactions: The Ester Dienolate [2,3]-Wittig/Oxy-Cope Rearrangement/Carbonyl Ene Reaction, a New Access to Substituted Carbocycles.
ChemInform, 2010Co-Authors: Martin HiersemannAbstract:The sequential ester dienolate [2,3]-Wittig/Oxy-Cope Rearrangement/carbonyl ene reaction has been investigated. Acyclic α,β-unsaturated α-allyloxy-substituted esters 1a−j were transformed into cyclopentane- or cyclohexanecarboxylates 6a−f and 7a−7d. This study presents a domino ester dienolate [2,3]-Wittig/Oxy-Cope Rearrangement or a domino Oxy-Cope Rearrangement/carbonyl ene reaction, depending on the substrate structure. The thermal intramolecular type-I carbonyl ene reaction as the terminating ring-closing reaction proceeds with high simple diastereoselectivity, but low induced diastereoselectivity. The corresponding type-II ene reaction afforded the cyclohexanecarboxylates 7a−d in high yield with complete simple and induced diastereoselectivity. Unfortunately, an attempted auxiliary-controlled enantioselective sequence was inefficient.
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Sequencing Pericyclic Reactions: The Ester Dienolate [2,3]‐Wittig/Oxy‐Cope Rearrangement/Carbonyl Ene Reaction, a New Access to Substituted Carbocycles
European Journal of Organic Chemistry, 2001Co-Authors: Martin HiersemannAbstract:The sequential ester dienolate [2,3]-Wittig/Oxy-Cope Rearrangement/carbonyl ene reaction has been investigated. Acyclic α,β-unsaturated α-allyloxy-substituted esters 1a−j were transformed into cyclopentane- or cyclohexanecarboxylates 6a−f and 7a−7d. This study presents a domino ester dienolate [2,3]-Wittig/Oxy-Cope Rearrangement or a domino Oxy-Cope Rearrangement/carbonyl ene reaction, depending on the substrate structure. The thermal intramolecular type-I carbonyl ene reaction as the terminating ring-closing reaction proceeds with high simple diastereoselectivity, but low induced diastereoselectivity. The corresponding type-II ene reaction afforded the cyclohexanecarboxylates 7a−d in high yield with complete simple and induced diastereoselectivity. Unfortunately, an attempted auxiliary-controlled enantioselective sequence was inefficient.
