The Experts below are selected from a list of 977385 Experts worldwide ranked by ideXlab platform
Geoffrey J. Roff - One of the best experts on this subject based on the ideXlab platform.
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Highly Regioselective Rhodium‐Catalysed Hydroformylation of Unsaturated Esters: The First Practical Method for Quaternary Selective Carbonylation
Chemistry: A European Journal, 2006Co-Authors: Matthew L. Clarke, Geoffrey J. RoffAbstract:Highly regioselective hydroformylation of unsaturated esters can be achieved when a highly reactive, ligand-modified, rhodium catalyst is employed near ambient temperatures (15-50 degrees C) and pressures over 30 bar. The use of 1,3,5,7-tetramethyl-2,4,8-trioxa-6-phosphaadamantane shows distinct advantages over other commonly applied phosphanes in terms of reaction rate, and regio- and chemoselectivity. Hydroformylation of a range 1,1-di- and 1,1,2-trisubstituted unsaturated esters yields quaternary aldehydes that are forbidden products according to Keulemans Rule. The aldehydes can be reductively aminated with molecular hydrogen to give Beta-Amino Acid esters in high yield. The overall green chemical process involves converting terminal alkynes into unusual Beta-Amino Acid esters with only water generated as an essential byproduct. This catalytic system has also been applied to the hydroformylation of simple 1,2-disubstitued unsaturated esters, which have been hydroformylated with excellent alpha-selectivity and good chemoselectivity for the first time.
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Highly regioselective rhodium-catalysed hydroformylation of unsaturated esters: the first practical method for quaternary selective carbonylation.
Chemistry (Weinheim an der Bergstrasse Germany), 2006Co-Authors: Matthew L. Clarke, Geoffrey J. RoffAbstract:Highly regioselective hydroformylation of unsaturated esters can be achieved when a highly reactive, ligand-modified, rhodium catalyst is employed near ambient temperatures (15-50 degrees C) and pressures over 30 bar. The use of 1,3,5,7-tetramethyl-2,4,8-trioxa-6-phosphaadamantane shows distinct advantages over other commonly applied phosphanes in terms of reaction rate, and regio- and chemoselectivity. Hydroformylation of a range 1,1-di- and 1,1,2-trisubstituted unsaturated esters yields quaternary aldehydes that are forbidden products according to Keulemans Rule. The aldehydes can be reductively aminated with molecular hydrogen to give Beta-Amino Acid esters in high yield. The overall green chemical process involves converting terminal alkynes into unusual Beta-Amino Acid esters with only water generated as an essential byproduct. This catalytic system has also been applied to the hydroformylation of simple 1,2-disubstitued unsaturated esters, which have been hydroformylated with excellent alpha-selectivity and good chemoselectivity for the first time.
Matthew L. Clarke - One of the best experts on this subject based on the ideXlab platform.
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Highly Regioselective Rhodium‐Catalysed Hydroformylation of Unsaturated Esters: The First Practical Method for Quaternary Selective Carbonylation
Chemistry: A European Journal, 2006Co-Authors: Matthew L. Clarke, Geoffrey J. RoffAbstract:Highly regioselective hydroformylation of unsaturated esters can be achieved when a highly reactive, ligand-modified, rhodium catalyst is employed near ambient temperatures (15-50 degrees C) and pressures over 30 bar. The use of 1,3,5,7-tetramethyl-2,4,8-trioxa-6-phosphaadamantane shows distinct advantages over other commonly applied phosphanes in terms of reaction rate, and regio- and chemoselectivity. Hydroformylation of a range 1,1-di- and 1,1,2-trisubstituted unsaturated esters yields quaternary aldehydes that are forbidden products according to Keulemans Rule. The aldehydes can be reductively aminated with molecular hydrogen to give Beta-Amino Acid esters in high yield. The overall green chemical process involves converting terminal alkynes into unusual Beta-Amino Acid esters with only water generated as an essential byproduct. This catalytic system has also been applied to the hydroformylation of simple 1,2-disubstitued unsaturated esters, which have been hydroformylated with excellent alpha-selectivity and good chemoselectivity for the first time.
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Highly regioselective rhodium-catalysed hydroformylation of unsaturated esters: the first practical method for quaternary selective carbonylation.
Chemistry (Weinheim an der Bergstrasse Germany), 2006Co-Authors: Matthew L. Clarke, Geoffrey J. RoffAbstract:Highly regioselective hydroformylation of unsaturated esters can be achieved when a highly reactive, ligand-modified, rhodium catalyst is employed near ambient temperatures (15-50 degrees C) and pressures over 30 bar. The use of 1,3,5,7-tetramethyl-2,4,8-trioxa-6-phosphaadamantane shows distinct advantages over other commonly applied phosphanes in terms of reaction rate, and regio- and chemoselectivity. Hydroformylation of a range 1,1-di- and 1,1,2-trisubstituted unsaturated esters yields quaternary aldehydes that are forbidden products according to Keulemans Rule. The aldehydes can be reductively aminated with molecular hydrogen to give Beta-Amino Acid esters in high yield. The overall green chemical process involves converting terminal alkynes into unusual Beta-Amino Acid esters with only water generated as an essential byproduct. This catalytic system has also been applied to the hydroformylation of simple 1,2-disubstitued unsaturated esters, which have been hydroformylated with excellent alpha-selectivity and good chemoselectivity for the first time.
Jeangerard Guillet - One of the best experts on this subject based on the ideXlab platform.
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melanoma peptide mart 1 27 35 analogues with enhanced binding capacity to the human class i histocompatibility molecule hla a2 by introduction of a β amino Acid residue implications for recognition by tumor infiltrating lymphocytes
Journal of Medicinal Chemistry, 2000Co-Authors: Gilles Guichard, Annette Zerbib, Johan Hoebeke, Francine Connan, Jeannine Choppin, Jeanpaul Briand, Jeangerard GuilletAbstract:: The design of heteroclytic antigens with high MHC binding capacity is of particular interest to overcome the weak immunogenicity of peptide epitopes derived from tissue antigens expressed by tumors. In the present study, double-substituted peptide analogues of the tumor-associated antigen MART-1(27-35) incorporating a substitution at a primary anchor residue and a Beta-Amino Acid residue at different positions in the sequence were synthesized and evaluated for binding to the human histocompatibility class I molecule HLA-A2 and for recognition by tumor-infiltrating lymphocytes. Interestingly, by combining a Leu for Ala substitution at P2 (which alone is deleterious for antigenic activity) with a Beta-Amino Acid substitution at a putative TCR contact residue, recognition by tumor-infiltrating lymphocytes was partially restored. The analogue [Leu(28),beta-HIle(30)]MART-1(27-35) displays both a higher affinity to HLA-A2 and a more prolonged complex stability compared to [Leu(28)]MART-1(27-35). Overall, these results suggest that double-substitution strategies and Beta-Amino Acid replacements at putative TCR contact residues might prove useful for the design of epitope mimics with high MHC binding capacity.
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Melanoma Peptide MART-1(27−35) Analogues with Enhanced Binding Capacity to the Human Class I Histocompatibility Molecule HLA-A2 by Introduction of a β-Amino Acid Residue: Implications for Recognition by Tumor-Infiltrating Lymphocytes
Journal of medicinal chemistry, 2000Co-Authors: Gilles Guichard, Annette Zerbib, Johan Hoebeke, Francine Connan, Jeannine Choppin, Jeanpaul Briand, Frédérique-anne Le Gal, Jeangerard GuilletAbstract:The design of heteroclytic antigens with high MHC binding capacity is of particular interest to overcome the weak immunogenicity of peptide epitopes derived from tissue antigens expressed by tumors. In the present study, double-substituted peptide analogues of the tumor-associated antigen MART-1(27-35) incorporating a substitution at a primary anchor residue and a Beta-Amino Acid residue at different positions in the sequence were synthesized and evaluated for binding to the human histocompatibility class I molecule HLA-A2 and for recognition by tumor-infiltrating lymphocytes. Interestingly, by combining a Leu for Ala substitution at P2 (which alone is deleterious for antigenic activity) with a Beta-Amino Acid substitution at a putative TCR contact residue, recognition by tumor-infiltrating lymphocytes was partially restored. The analogue [Leu(28),beta-HIle(30)]MART-1(27-35) displays both a higher affinity to HLA-A2 and a more prolonged complex stability compared to [Leu(28)]MART-1(27-35). Overall, these results suggest that double-substitution strategies and Beta-Amino Acid replacements at putative TCR contact residues might prove useful for the design of epitope mimics with high MHC binding capacity.
Pierre-yves Renard - One of the best experts on this subject based on the ideXlab platform.
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Facile and rapid access to linear and truncated microcystin analogues for the implementation of immunoassays.
Organic and Biomolecular Chemistry, 2010Co-Authors: Guillaume Clave, H. Boutal, N. Kreich, Hervé Volland, Anthony Romieu, Xavier Franck, Claudio Ronco, Pierre-yves RenardAbstract:A series of simplified microcystin-LR analogues based on Adda [(2S,3S,8S,9S,4E,6E)-3-amino-9-methoxy-2,6,8-trimethyl-10-phenyldecadienoic Acid] or its corresponding aldol precursor linked to a polypeptide moiety have been synthesised and assessed for their binding affinity by the monoclonal antibody mAb MC159, an anti-microcystin-LR mAb recently selected by us for the detection of microcystins through various immunoassay formats. Some modifications have been brought to the enantiospecific synthesis of N-Boc-Adda developed by Pearson et al. (Org. Lett., 2000, 2, 2901) which enabled us to access in an economical and time-saving manner a small library of MC-LR linear analogues. Among which Adda was chosen to synthesise, as an illustrative example, a fluorescent probe derived from this Beta-Amino Acid. This probe was subsequently solid-phase immobilised by means of oxime ligation in order to lead to biochips suitable for microcystin detection through the SPIT-FRI method.
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Facile and rapid access to linear and truncated microcystin analogues for the implementation of immunoassays.
Organic and Biomolecular Chemistry, 2010Co-Authors: Guillaume Clave, H. Boutal, N. Kreich, Hervé Volland, Anthony Romieu, Xavier Franck, Claudio Ronco, Pierre-yves RenardAbstract:A series of simplified microcystin-LR analogues based on Adda [(2S,3S,8S,9S,4E,6E)-3-amino-9-methoxy-2,6,8-trimethyl-10-phenyldecadienoic Acid] or its corresponding aldol precursor linked to a polypeptide moiety have been synthesised and assessed for their binding affinity by the monoclonal antibody mAb MC159, an anti-microcystin-LR mAb recently selected by us for the detection of microcystins through various immunoassay formats. Some modifications have been brought to the enantiospecific synthesis of N-Boc-Adda developed by Pearson et al. (Org. Lett., 2000, 2, 2901) which enabled us to access in an economical and time-saving manner a small library of MC-LR linear analogues. Among which Adda was chosen to synthesise, as an illustrative example, a fluorescent probe derived from this Beta-Amino Acid. This probe was subsequently solid-phase immobilised by means of oxime ligation in order to lead to biochips suitable for microcystin detection through the SPIT-FRI method.
Yury O. Tsybin - One of the best experts on this subject based on the ideXlab platform.
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Radical Stability Directs Electron Capture and Transfer Dissociation of β‐Amino Acids in Peptides
Chemistry: A European Journal, 2010Co-Authors: Hisham Ben Hamidane, Aleksey Vorobyev, Maud Larregola, Aneta Lukaszuk, Philippe Karoyan, Dirk Tourwé, Solange Lavielle, Yury O. TsybinAbstract:We report on the characteristics of the radical-ion-driven dissociation of a diverse array of Beta-Amino Acids incorporated into alpha-peptides, as probed by tandem electron-capture and electron-transfer dissociation (ECD/ETD) mass spectrometry. The reported results demonstrate a stronger ECD/ETD dependence on the nature of the amino Acid side chain for Beta-Amino Acids than for their alpha-form counterparts. In particular, only aromatic (e.g., beta-Phe), and to a substantially lower extent, carbonyl-containing (e.g., beta-Glu and beta-Gln) amino Acid side chains, lead to N-C-beta bond cleavage in the corresponding Beta-Amino Acids. We conclude that radical stabilization must be provided by the side chain to enable the radical-driven fragmentation from the nearby backbone carbonyl carbon to proceed. In contrast with the cleavage of backbones derived from alpha-amino Acids. ECD of peptides composed mainly of Beta-Amino Acids reveals a shift in cleavage priority from the N-C-beta to the C-alpha-C bond. The incorporation of CH2 groups into the peptide backbone may thus drastically influence the backbone charge solvation preference. The characteristics of radical-driven Beta-Amino Acid dissociation described herein are of particular importance to methods development, applications in peptide sequencing, and peptide and protein modification (e.g., deamidation and isomerization) analysis in life science research. mainly of Beta-Amino Acids reveals a shift in cleavage priority from the N-C-beta to the C-alpha-C bond. The incorporation of CH2 groups into the peptide backbone may thus drastically influence the backbone charge solvation preference. The characteristics of radical-driven Beta-Amino Acid dissociation described herein are of particular importance to methods development, applications in peptide sequencing, and peptide and protein modification (e.g., deamidation and isomerization) analysis in life science research.
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Radical stability directs electron capture and transfer dissociation of β-amino Acids in peptides.
Chemistry (Weinheim an der Bergstrasse Germany), 2010Co-Authors: Hisham Ben Hamidane, Aleksey Vorobyev, Maud Larregola, Aneta Lukaszuk, Philippe Karoyan, Dirk Tourwé, Solange Lavielle, Yury O. TsybinAbstract:We report on the characteristics of the radical-ion-driven dissociation of a diverse array of Beta-Amino Acids incorporated into alpha-peptides, as probed by tandem electron-capture and electron-transfer dissociation (ECD/ETD) mass spectrometry. The reported results demonstrate a stronger ECD/ETD dependence on the nature of the amino Acid side chain for Beta-Amino Acids than for their alpha-form counterparts. In particular, only aromatic (e.g., beta-Phe), and to a substantially lower extent, carbonyl-containing (e.g., beta-Glu and beta-Gln) amino Acid side chains, lead to N-C-beta bond cleavage in the corresponding Beta-Amino Acids. We conclude that radical stabilization must be provided by the side chain to enable the radical-driven fragmentation from the nearby backbone carbonyl carbon to proceed. In contrast with the cleavage of backbones derived from alpha-amino Acids. ECD of peptides composed mainly of Beta-Amino Acids reveals a shift in cleavage priority from the N-C-beta to the C-alpha-C bond. The incorporation of CH2 groups into the peptide backbone may thus drastically influence the backbone charge solvation preference. The characteristics of radical-driven Beta-Amino Acid dissociation described herein are of particular importance to methods development, applications in peptide sequencing, and peptide and protein modification (e.g., deamidation and isomerization) analysis in life science research. mainly of Beta-Amino Acids reveals a shift in cleavage priority from the N-C-beta to the C-alpha-C bond. The incorporation of CH2 groups into the peptide backbone may thus drastically influence the backbone charge solvation preference. The characteristics of radical-driven Beta-Amino Acid dissociation described herein are of particular importance to methods development, applications in peptide sequencing, and peptide and protein modification (e.g., deamidation and isomerization) analysis in life science research.
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Radical Stability Directs Electron Capture and Transfer Dissociation of Beta-Amino Acids in Peptides.
Chemistry - A European Journal, 2010Co-Authors: Hisham, Ben Hamidane,, Aleksey Vorobyev, Aneta Lukaszuk, Philippe Karoyan, Larregola Maud, Tourwé Dirk, Lavielle Solange, Yury O. TsybinAbstract:We report on the characteristics of the radical-ion-driven dissociation of a diverse array of Beta-Amino Acids incorporated into alpha-peptides, as probed by tandem electron-capture and electron-transfer dissociation (ECD/ETD) mass spectrometry. The reported results demonstrate a stronger ECD/ETD dependence on the nature of the amino Acid side chain for Beta-Amino Acids than for their alpha-form counterparts. In particular, only aromatic (e.g., beta-Phe), and to a substantially lower extent, carbonyl-containing (e.g., beta-Glu and beta-Gln) amino Acid side chains, lead to N--C(beta) bond cleavage in the corresponding Beta-Amino Acids. We conclude that radical stabilization must be provided by the side chain to enable the radical-driven fragmentation from the nearby backbone carbonyl carbon to proceed. In contrast with the cleavage of backbones derived from alpha-amino Acids, ECD of peptides composed mainly of Beta-Amino Acids reveals a shift in cleavage priority from the N--C(beta) to the C(alpha)--C bond. The incorporation of CH(2) groups into the peptide backbone may thus drastically influence the backbone charge solvation preference. The characteristics of radical-driven Beta-Amino Acid dissociation described herein are of particular importance to methods development, applications in peptide sequencing, and peptide and protein modification (e.g., deamidation and isomerization) analysis in life science research.
