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Pengfei Wang - One of the best experts on this subject based on the ideXlab platform.
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1 3 diethylamino phenyl ethyl deape a photolabile protecting group for hydroxyl and carboxyl groups
Journal of Organic Chemistry, 2018Co-Authors: Xiong Ding, Pengfei WangAbstract:Herein we demonstrate that the photolabile protecting group (PPG), the 1-[3-(diethylamino)-phenyl]ethyl (DEAPE) group, has dramatically different photochemical properties from the parent 3-(diethylamino)benzyl (DEABn) PPG. The new PPG, derived from DEABn by adding a methyl group to the benzylic carbon, has similar reactivity as DEABn in releasing alcohol in MeCN/water; however, it is more efficient than DEABn in releasing carboxylic acid. In particular, it can release carboxylic acid efficiently in aprotic solvents and the PPG itself converts to 3-diethylaminostyrene. Photochemical removal of DEAPE can also be conveniently carried out with sunlight. The results in this work suggest that there probably exist multiple reaction pathways in cleaving the benzylic C–O bond and they can be affected by the benzylic substitution and the reaction conditions.
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1‑[3-(Diethylamino)phenyl]ethyl (DEAPE): A Photolabile Protecting Group for Hydroxyl and Carboxyl Groups
2018Co-Authors: Xiong Ding, Pengfei WangAbstract:Herein we demonstrate that the photolabile protecting group (PPG), the 1-[3-(diethylamino)-phenyl]ethyl (DEAPE) group, has dramatically different photochemical properties from the parent 3-(diethylamino)benzyl (DEABn) PPG. The new PPG, derived from DEABn by adding a methyl group to the benzylic carbon, has similar reactivity as DEABn in releasing alcohol in MeCN/water; however, it is more efficient than DEABn in releasing carboxylic acid. In particular, it can release carboxylic acid efficiently in aprotic solvents and the PPG itself converts to 3-diethylaminostyrene. Photochemical removal of DEAPE can also be conveniently carried out with sunlight. The results in this work suggest that there probably exist multiple reaction pathways in cleaving the benzylic C–O bond and they can be affected by the benzylic substitution and the reaction conditions
Xiong Ding - One of the best experts on this subject based on the ideXlab platform.
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1 3 diethylamino phenyl ethyl deape a photolabile protecting group for hydroxyl and carboxyl groups
Journal of Organic Chemistry, 2018Co-Authors: Xiong Ding, Pengfei WangAbstract:Herein we demonstrate that the photolabile protecting group (PPG), the 1-[3-(diethylamino)-phenyl]ethyl (DEAPE) group, has dramatically different photochemical properties from the parent 3-(diethylamino)benzyl (DEABn) PPG. The new PPG, derived from DEABn by adding a methyl group to the benzylic carbon, has similar reactivity as DEABn in releasing alcohol in MeCN/water; however, it is more efficient than DEABn in releasing carboxylic acid. In particular, it can release carboxylic acid efficiently in aprotic solvents and the PPG itself converts to 3-diethylaminostyrene. Photochemical removal of DEAPE can also be conveniently carried out with sunlight. The results in this work suggest that there probably exist multiple reaction pathways in cleaving the benzylic C–O bond and they can be affected by the benzylic substitution and the reaction conditions.
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1‑[3-(Diethylamino)phenyl]ethyl (DEAPE): A Photolabile Protecting Group for Hydroxyl and Carboxyl Groups
2018Co-Authors: Xiong Ding, Pengfei WangAbstract:Herein we demonstrate that the photolabile protecting group (PPG), the 1-[3-(diethylamino)-phenyl]ethyl (DEAPE) group, has dramatically different photochemical properties from the parent 3-(diethylamino)benzyl (DEABn) PPG. The new PPG, derived from DEABn by adding a methyl group to the benzylic carbon, has similar reactivity as DEABn in releasing alcohol in MeCN/water; however, it is more efficient than DEABn in releasing carboxylic acid. In particular, it can release carboxylic acid efficiently in aprotic solvents and the PPG itself converts to 3-diethylaminostyrene. Photochemical removal of DEAPE can also be conveniently carried out with sunlight. The results in this work suggest that there probably exist multiple reaction pathways in cleaving the benzylic C–O bond and they can be affected by the benzylic substitution and the reaction conditions
Demni Nizar - One of the best experts on this subject based on the ideXlab platform.
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Markov semi-groups associated with the complex unimodular group $Sl(2,\mathbb{C})$
2019Co-Authors: Demni NizarAbstract:In this paper, we derive the explicit expressions of two Markov semi-groups constructed by P. Biane in \cite{Bia1} from the restriction of a particular positive definite function on the complex unimodular group $Sl(2,\mathbb{C})$ to two commutative subalgebras of its universal $C^{\star}$-algebra. Our computations use Euclidean Fourier analysis together with the generating function of Laguerre polynomials with index $-1$, and yield absolutely-convergent double series representations of the semi-group densities. In the last part of the paper, we discuss the coincidence, noticed by Biane as well, occurring between the heat kernel on the Heisenberg group and the semi-group corresponding to the intersection of the principal and the complementary series. To this end, we appeal to the metaplectic representation $Mp(4,\mathbb{R})$ and to the Landau operator in the complex plane.Comment: The intertwining operator is derived in the case of principal serie
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Markov semi-groups associated with the complex unimodular group $Sl(2,\mathbb{C})$
Springer Verlag, 2019Co-Authors: Demni NizarAbstract:The intertwining operator is derived in the case of principal seriesInternational audienceIn this paper, we derive the explicit expressions of two Markov semi-groups constructed by P. Biane in \cite{Bia1} from the restriction of a particular positive definite function on the complex unimodular group $Sl(2,\mathbb{C})$ to two commutative subalgebras of its universal $C^{\star}$-algebra. Our computations use Euclidean Fourier analysis together with the generating function of Laguerre polynomials with index $-1$, and yield absolutely-convergent double series representations of the semi-group densities. In the last part of the paper, we discuss the coincidence, noticed by Biane as well, occurring between the heat kernel on the Heisenberg group and the semi-group corresponding to the intersection of the principal and the complementary series. To this end, we appeal to the metaplectic representation $Mp(4,\mathbb{R})$ and to the Landau operator in the complex plane
Zimmermann, Bruno P. - One of the best experts on this subject based on the ideXlab platform.
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Tetrahedral Coxeter groups, large group-actions on 3-manifolds and equivariant Heegaard splittings
2020Co-Authors: Zimmermann, Bruno P.Abstract:We consider finite group-actions on closed, orientable and nonorientable 3-manifolds M which preserve the two handlebodies of a Heegaard splitting of M of some genus g > 1 (maybe interchanging the two handlebodies). The maximal possible order of a finite group-action on a handlebody of genus g>1 is 12(g-1) in the orientation-preserving case and 24(g-1) in general, and the maximal order of a finite group preserving the Heegaard surface of a Heegaard splitting of genus g is 48(g-1). This defines a hierarchy for finite group-actions on 3-manifolds which we discuss in the present paper; we present various manifolds with an action of type 48(g-1) for small values of g, and in particular the unique hyperbolic 3-manifold with such an action of smallest possible genus g = 6 (in strong analogy with the Euclidean case of the 3-torus which has such actions for g = 3).Comment: 11 page
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Tetrahedral Coxeter groups, large group-actions on 3-manifolds and equivariant Heegaard splittings
EUT Edizioni Università di Trieste, 2020Co-Authors: Zimmermann, Bruno P.Abstract:We consider finite group-actions on closed, orientable and nonorientable 3-manifolds M which preserve the two handlebodies of a Heegaard splitting of M of some genus g > 1 (maybe interchanging the two handlebodies). The maximal possible order of a finite group-action on a handlebody of genus g > 1 is 12(g — 1) in the orientation-preserving case and 24(g — 1) in general, and the maximal order of a finite group preserving the Heegaard surface of a Heegaard splitting of genus g is 48(g —1). This defines a hierarchy for finite group-actions on 3-manifolds which we discuss in the present paper; we present various manifolds with an action of type 48(g — 1) for small values of g, and in particular the unique hyperbolic 3-manifold with such an action of smallest possible genus g = 6 (in strong analogy with the Euclidean case of the 3-torus which has such actions for g = 3)
Thomas Ziegler - One of the best experts on this subject based on the ideXlab platform.
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the 2 triphenylsilyl ethoxycarbonyl tpseoc group a new silicon based fluoride cleavable oxycarbonyl protecting group highly orthogonal to the boc fmoc and cbz groups
Molecules, 2011Co-Authors: Martin Golkowski, Thomas ZieglerAbstract:Starting from 2-(triphenylsilyl)ethanol a new oxycarbonyl protecting group cleavable by fluoride ion induced Peterson-elimination has been developed. Known 2-(triphenylsilyl)ethanol has been prepared from commercially available triphenylvinyl-silane by a hydroboration-oxidation sequence using the sterically hindered borane reagent 9-BBN. The silyl alcohol was subsequently transformed into its chloroformate, imidazolylcarboxylic acid ester and p-nitrophenyl carbonate and used in standard protocols for the formation of carbamates and carbonates. The Tpseoc group proved to be highly resistant against acidic conditions applied in removal of tert-butyl esters and the t-Boc-group. It also withstood catalytic hydrogenation, treatment with morpholine, methylhydrazine and Pd-reagents/allyl-scavanger combinations, conditions required to cleave Cbz-, Fmoc-, phthalimide- and Alloc-groups. The Tpseoc-group is cleaved upon treatment with TBAF/CsF at 0 °C or r.t. with cleavage times reaching from < 10 min. to 24 h. Its orthogonality, ease of cleavage and UV-detectability makes the Tpseoc-group a promising alternative to other widely used silicon based amine protecting groups like the Teoc- and SES-groups.
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the 2 2 chloroacetoxyethyl benzoyl group stable to hydrogenolysis and cleavable beside other acyl groups
Tetrahedron Letters, 1995Co-Authors: Thomas Ziegler, G PantkowskiAbstract:Abstract The 2-(2-chloroacetoxyethyl)benzoyl (CAEB) group is prepared from isochromane in 4 steps and used as a temporary protecting group for carbohydrates. The CAEB group functions as a neighboring active, 1,2- trans -directing blocking group for glycosyl donors. It does not show transesterification to less reactive nucleophiles and is stable toward hydrogenolysis. CAEB can be cleaved off with thiourea and without effecting other acyl groups. It is suited for orthogonal protection strategies in combination with acetyl, benzoyl, benzyl and benzylidene groups in saccharide synthesis.
