The Experts below are selected from a list of 318 Experts worldwide ranked by ideXlab platform
Alois Furstner - One of the best experts on this subject based on the ideXlab platform.
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synthesis of Phenanthrenes and polycyclic heteroarenes by transition metal catalyzed cycloisomerization reactions
Chemistry: A European Journal, 2004Co-Authors: Victor Mamane, Peter Hannen, Alois FurstnerAbstract:Readily available biphenyl derivatives containing an alkyne unit at one of their ortho-positions are converted into substituted Phenanthrenes on exposure to catalytic amounts of either PtCl 2 , AuCl, AuCl 3 , GaCl 3 or InCl 3 in toluene. This 6-endo-dig cyclization likely proceeds through initial π-complexation of the alkyne unit followed by interception of the resulting η 2 -metal species by the adjacent arene ring. The reaction is inherently modular, allowing for substantial structural variations and for the incorporation of substituents at any site of the phenanthrene product. Moreover, it is readily extended to the heterocyclic series as exemplified by the preparation of benzoindoles, benzocarbazoles, naphthothiophenes, as well as bridgehead nitrogen heterocycles such as pyrrolo[1,2-a]quinolines. Depending on the chosen catalyst, biaryls bearing halo-alkyne units can either be converted into the corresponding 10-halo-Phenanthrenes or into the isomeric 9-halo-Phenanthrenes; in the latter case, the concomitant 1,2-halide shift is best explained by assuming a metal vinylidene species as the reactive intermediate. The scope of this novel method for the preparation of polycyclic arenes is illustrated by the total synthesis of a series of poly-oxygenated Phenanthrenes that are close relatives of the anticancer agent combretastatin A-4, as well as by the total synthesis of the aporphine alkaloid O-methyl-dehydroisopiline and its naturally occurring symmetrical dimer.
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flexible synthesis of Phenanthrenes by a ptcl2 catalyzed cycloisomerization reaction
Journal of Organic Chemistry, 2002Co-Authors: Alois Furstner, Victor MamaneAbstract:Readily available biphenyl derivatives containing an alkyne unit at one of their ortho positions are converted into substituted Phenanthrenes upon exposure to catalytic amounts of either PtCl2, AuCl3, GaCl3, or InCl3 in toluene. This 6-endo-dig cyclization likely proceeds through initial π-coordination of the alkyne unit followed by interception of the resulting η2-metal complex by the adjacent arene ring. The reaction is inherently modular, allowing for substantial structural variations and for the incorporation of substituents at any site of the phenanthrene product except C-9. Moreover, the reaction is readily applied to the heterocyclic series as exemplified by the preparation of benzoindoles, naphthothiophenes as well as bridgehead nitrogen heterocycles.
Victor Mamane - One of the best experts on this subject based on the ideXlab platform.
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synthesis of Phenanthrenes and polycyclic heteroarenes by transition metal catalyzed cycloisomerization reactions
Chemistry: A European Journal, 2004Co-Authors: Victor Mamane, Peter Hannen, Alois FurstnerAbstract:Readily available biphenyl derivatives containing an alkyne unit at one of their ortho-positions are converted into substituted Phenanthrenes on exposure to catalytic amounts of either PtCl 2 , AuCl, AuCl 3 , GaCl 3 or InCl 3 in toluene. This 6-endo-dig cyclization likely proceeds through initial π-complexation of the alkyne unit followed by interception of the resulting η 2 -metal species by the adjacent arene ring. The reaction is inherently modular, allowing for substantial structural variations and for the incorporation of substituents at any site of the phenanthrene product. Moreover, it is readily extended to the heterocyclic series as exemplified by the preparation of benzoindoles, benzocarbazoles, naphthothiophenes, as well as bridgehead nitrogen heterocycles such as pyrrolo[1,2-a]quinolines. Depending on the chosen catalyst, biaryls bearing halo-alkyne units can either be converted into the corresponding 10-halo-Phenanthrenes or into the isomeric 9-halo-Phenanthrenes; in the latter case, the concomitant 1,2-halide shift is best explained by assuming a metal vinylidene species as the reactive intermediate. The scope of this novel method for the preparation of polycyclic arenes is illustrated by the total synthesis of a series of poly-oxygenated Phenanthrenes that are close relatives of the anticancer agent combretastatin A-4, as well as by the total synthesis of the aporphine alkaloid O-methyl-dehydroisopiline and its naturally occurring symmetrical dimer.
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flexible synthesis of Phenanthrenes by a ptcl2 catalyzed cycloisomerization reaction
Journal of Organic Chemistry, 2002Co-Authors: Alois Furstner, Victor MamaneAbstract:Readily available biphenyl derivatives containing an alkyne unit at one of their ortho positions are converted into substituted Phenanthrenes upon exposure to catalytic amounts of either PtCl2, AuCl3, GaCl3, or InCl3 in toluene. This 6-endo-dig cyclization likely proceeds through initial π-coordination of the alkyne unit followed by interception of the resulting η2-metal complex by the adjacent arene ring. The reaction is inherently modular, allowing for substantial structural variations and for the incorporation of substituents at any site of the phenanthrene product except C-9. Moreover, the reaction is readily applied to the heterocyclic series as exemplified by the preparation of benzoindoles, naphthothiophenes as well as bridgehead nitrogen heterocycles.
Umasish Jana - One of the best experts on this subject based on the ideXlab platform.
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iron catalyzed tandem carbon carbon carbon oxygen bond formation aromatization of 2 alkynyl biphenyl 2 carbinols a new approach to the synthesis of substituted Phenanthrenes
Tetrahedron Letters, 2015Co-Authors: Krishnendu Bera, Soumen Sarkar, Umasish JanaAbstract:An iron-catalyzed efficient synthesis of substituted Phenanthrenes through tandem intramolecular C–C/C–O bond formations/aromatization of 2′-alkynyl-biphenyl-2-carbinols is reported. This method provides a novel, highly efficient, and straightforward route to 9,10-substituted phenanthrene in good to excellent yields. The present strategy involves tandem Fe(OTf)3-catalyzed generation of benzylic carbocation, 6-exo-dig cyclization of alkyne, carbon–oxygen bond formation, and aromatization steps in one pot.
Jianbo Wang - One of the best experts on this subject based on the ideXlab platform.
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synthesis of Phenanthrenes through copper catalyzed cross coupling of n tosylhydrazones with terminal alkynes
Journal of Organic Chemistry, 2014Co-Authors: Mohammad Lokman Hossain, Fei Ye, Lei Zhou, Yan Zhang, Jianbo WangAbstract:A novel protocol for the synthesis of Phenanthrenes through the copper-catalyzed reaction of aromatic tosylhydrazones with terminal alkynes is explored. The reaction proceeds via the formation of an allene intermediate and subsequent six-π-electron cyclization–isomerization, affording phenanthrene derivatives in good yields. The transformation can be performed in two ways: (1) with N-tosylhydrazones derived from [1,1′-biphenyl]-2-carbaldehydes and terminal alkynes as the starting materials and (2) with N-tosylhydrazones derived from aromatic aldehydes and 2-alkynyl biphenyls as the starting materials. This new phenanthrene synthesis uses readily available starting materials and a cheap copper catalyst and has a wide range of functional group compatibility.
Krishnendu Bera - One of the best experts on this subject based on the ideXlab platform.
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iron catalyzed tandem carbon carbon carbon oxygen bond formation aromatization of 2 alkynyl biphenyl 2 carbinols a new approach to the synthesis of substituted Phenanthrenes
Tetrahedron Letters, 2015Co-Authors: Krishnendu Bera, Soumen Sarkar, Umasish JanaAbstract:An iron-catalyzed efficient synthesis of substituted Phenanthrenes through tandem intramolecular C–C/C–O bond formations/aromatization of 2′-alkynyl-biphenyl-2-carbinols is reported. This method provides a novel, highly efficient, and straightforward route to 9,10-substituted phenanthrene in good to excellent yields. The present strategy involves tandem Fe(OTf)3-catalyzed generation of benzylic carbocation, 6-exo-dig cyclization of alkyne, carbon–oxygen bond formation, and aromatization steps in one pot.
