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Gerard Rousseau - One of the best experts on this subject based on the ideXlab platform.
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preparation of halo enol phostones by reaction of acetylenic phosphonate monoesters with bis Collidine halo hexafluorophosphate
Tetrahedron Letters, 2008Co-Authors: Virginie Andre, Sylvie Robin, Gerard RousseauAbstract:Abstract Reaction of non-conjugated acetylenic phosphonate monoesters with (bis-Collidine) bromo and iodo hexafluorophosphates was found to lead to the formation of halo enol phostones. Depending on the size of the heterocyclic compounds formed (6–8-membered compounds), endo or a mixture of endo and exo cyclization products were obtained.
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bis sym Collidine bromine i hexafluorophosphate
e-EROS Encyclopedia of Reagents for Organic Synthesis, 2003Co-Authors: Gerard RousseauAbstract:[188944-77-6] C16H22BrF6N2P (MW 467.23) InChI = 1/2C8H11N.BrH2.F6P/c2*1-6-4-7(2)9-8(3)5-6;;1-7(2,3,4,5)6/h2*4-5H,1-3H3;1H2;/q;;+1;-1 InChIKey = XXEBKZOPQLEZSZ-UHFFFAOYAV (reagent used as a source of positive bromine) Physical Data: mp 127–128 °C. Solubility: soluble in methylene chloride and most organic solvents. Form Supplied in: white solid. Analysis of Reagent Purity: NMR and melting point. Preparative Methods: preparation of this reagent is reported in reference 1. Purification: recrystallization from methylene chloride. Handling, Storage, and Precautions: the solid can be weighed and handled without special care. It is preferable to store it in the dark at 0 °C. Under these conditions, it can be kept for several years. Incompatible with strong acids and reducing agents. Decomposes on prolonged exposure to light.
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preparation of oxocanes by electrophilic cyclizations of unsaturated alcohols in the presence of bis Collidine halonium i hexafluorophosphates
ChemInform, 2003Co-Authors: Christelle Mendes, Sylvie Renard, Mazin Rofoo, Marieclaude Roux, Gerard RousseauAbstract:7-Octen-1-ols substituted in the sp3−sp3 carbon chain with carbocyclic (phenyl and cyclopropane) and heterocyclic (epoxide and dioxolane) moieties were prepared and their cyclizations in the presence of bis(Collidine)iodonium(I) and -bromonium(I) hexafluorophosphates as electrophiles were studied. Oxocanes were obtained in modest to good yields when a rigid cyclic moiety (cyclopropane or phenyl) was present in the chain, while yields of cyclizations were lower if the cyclic component had a certain flexibility (dioxolane). Low yields were obtained with substrates bearing an epoxide substituent, probably because of stability problems due to the presence of Collidine. With the vinylcyclopropane alcohol 12 we observed mainly the opening of the cyclopropane ring and the cyclization produced a tetrahydropyran derivative. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
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preparation of oxetanes by 4 endo trig electrophilic cyclisations of cinnamic alcohols
Tetrahedron Letters, 2001Co-Authors: Sébastien Albert, Sylvie Robin, Gerard RousseauAbstract:Abstract The reaction of substituted cinnamic alcohols with bis( sym -Collidine)bromine(I) hexafluorophosphate was examined. In general no oxetane was obtained when a substituent was fixed on the carboncarbon double bond. However, oxetanes were formed in high yields when two substituents were present in α of the alcohol function.
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preparation of oxetanes by silicon directed 4 exo trig electrophilic cyclisations of homoallylic alcohols
Tetrahedron Letters, 2001Co-Authors: Mazin Rofoo, Marieclaude Roux, Gerard RousseauAbstract:Abstract The reaction of homoallylic alcohols with bis(sym-Collidine)bromine(I) hexafluoroantimonate led in good yields to the formation of oxetanes if a silyl group was fixed on the carboncarbon double bond in terminal position. This reaction was stereospecific when no supplementary substituent was present on the double bond.
Franz A Mautner - One of the best experts on this subject based on the ideXlab platform.
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synthesis and structural determination of azidotetrakis 3 ethyl 4methylpyridine copper ii perchlorate and di μ 1 1 azido diazidotetrakis 3 ethyl 4 methylpyridine dicopper ii cu β Collidine 4 n3 clo4 and cu β Collidine 2 n3 2 2
Polyhedron, 1996Co-Authors: Franz A Mautner, Mohamed A S GoherAbstract:Abstract The preparation and structural characterizations of two new copper(II) azido complexes of 3-ethyl-4-methylpyridine (β-Collidine), namely azido tetrakis(β-Collidine) copper(II) perchlorate (1) and di-μ(l,l)-azido-[diazido-tetrakis(β-Collidine)]dicopper(II) (2) are described. The spectral results suggest an ionic perchlorate and terminal azido group in complex 1 and different asymmetric azides in 2. The structure of 1 consists of isolated [Cu(β-Collidine)4(N3)]+ cations and ClO4− anions. The copper atom in the cation is in a tetragonal pyramidal environment with four Collidine ligands occupying the basal sites [CuN 2.033(4) A] and a terminal azido ligand at the apical position with a CuN distance of 2.141(6) A. The centrosymmetric binuclear molecule 2 features monodentate Collidine ligands, di-μ(l,l)-azido-bridged Cu2N2 rings, terminal azido ligands and distorted square pyramidal copper(II) coordination geometry.
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synthesis crystal structure and spectroscopic study of trans diazidobis 2 4 6 trimethylpyridine copper ii and azidotetrakis 3 ethyl 4 methylpyridine copper ii nitrate cu s Collidine 2 n3 2 and cu β Collidine 4 n3 no3
Polyhedron, 1996Co-Authors: Mohamed A S Goher, Franz A MautnerAbstract:Abstract Two monomeric complexes of copper(II) azide with 2,4,6-trimethylpyridine and 3-ethyl-4-methylpyridine, namely trans-diazidobis(s-Collidine)copper(II) (1) and azidotetrakis-(β-Collidine)copper(II) nitrate (2), have been prepared and characterized by spectroscopic and X-ray crystallographic methods. The spectral results suggest terminal azido ligands in both complexes and ionic nitrate in 2. The structure of 1 consists of isolated polyhedra of trans-[Cu(2,4,6,-trimethylpyridine)2(N3)2], in which the copper atom is located at the inversion centre and has an almost regular square-planar geometry. The CuN(N3) and CuN(L) bond lengths are 1.954(4) and 2.022(3) A, respectively. The terminal azido ligands are linear and slightly asymmetric [ N α N β = 1.184(5) and N β N γ = 1.163(6) A ] . The structure of complex 2 consists of isolated [Cu(3-ethyl-4-methylpyridine)4(N3]+ cations and NO3− counter anions. The coordination of the copper atom in the cation is a regular tetragonal pyramid with four Collidine ligands occupying the basal sites [ Cu N av = 2.028(10) A ] and a terminal azido ligand at the apical position with a CuN distance of 2.193(7) A.
Mohamed A S Goher - One of the best experts on this subject based on the ideXlab platform.
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synthesis and structural determination of azidotetrakis 3 ethyl 4methylpyridine copper ii perchlorate and di μ 1 1 azido diazidotetrakis 3 ethyl 4 methylpyridine dicopper ii cu β Collidine 4 n3 clo4 and cu β Collidine 2 n3 2 2
Polyhedron, 1996Co-Authors: Franz A Mautner, Mohamed A S GoherAbstract:Abstract The preparation and structural characterizations of two new copper(II) azido complexes of 3-ethyl-4-methylpyridine (β-Collidine), namely azido tetrakis(β-Collidine) copper(II) perchlorate (1) and di-μ(l,l)-azido-[diazido-tetrakis(β-Collidine)]dicopper(II) (2) are described. The spectral results suggest an ionic perchlorate and terminal azido group in complex 1 and different asymmetric azides in 2. The structure of 1 consists of isolated [Cu(β-Collidine)4(N3)]+ cations and ClO4− anions. The copper atom in the cation is in a tetragonal pyramidal environment with four Collidine ligands occupying the basal sites [CuN 2.033(4) A] and a terminal azido ligand at the apical position with a CuN distance of 2.141(6) A. The centrosymmetric binuclear molecule 2 features monodentate Collidine ligands, di-μ(l,l)-azido-bridged Cu2N2 rings, terminal azido ligands and distorted square pyramidal copper(II) coordination geometry.
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synthesis crystal structure and spectroscopic study of trans diazidobis 2 4 6 trimethylpyridine copper ii and azidotetrakis 3 ethyl 4 methylpyridine copper ii nitrate cu s Collidine 2 n3 2 and cu β Collidine 4 n3 no3
Polyhedron, 1996Co-Authors: Mohamed A S Goher, Franz A MautnerAbstract:Abstract Two monomeric complexes of copper(II) azide with 2,4,6-trimethylpyridine and 3-ethyl-4-methylpyridine, namely trans-diazidobis(s-Collidine)copper(II) (1) and azidotetrakis-(β-Collidine)copper(II) nitrate (2), have been prepared and characterized by spectroscopic and X-ray crystallographic methods. The spectral results suggest terminal azido ligands in both complexes and ionic nitrate in 2. The structure of 1 consists of isolated polyhedra of trans-[Cu(2,4,6,-trimethylpyridine)2(N3)2], in which the copper atom is located at the inversion centre and has an almost regular square-planar geometry. The CuN(N3) and CuN(L) bond lengths are 1.954(4) and 2.022(3) A, respectively. The terminal azido ligands are linear and slightly asymmetric [ N α N β = 1.184(5) and N β N γ = 1.163(6) A ] . The structure of complex 2 consists of isolated [Cu(3-ethyl-4-methylpyridine)4(N3]+ cations and NO3− counter anions. The coordination of the copper atom in the cation is a regular tetragonal pyramid with four Collidine ligands occupying the basal sites [ Cu N av = 2.028(10) A ] and a terminal azido ligand at the apical position with a CuN distance of 2.193(7) A.
Sylvie Robin - One of the best experts on this subject based on the ideXlab platform.
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preparation of halo enol phostones by reaction of acetylenic phosphonate monoesters with bis Collidine halo hexafluorophosphate
Tetrahedron Letters, 2008Co-Authors: Virginie Andre, Sylvie Robin, Gerard RousseauAbstract:Abstract Reaction of non-conjugated acetylenic phosphonate monoesters with (bis-Collidine) bromo and iodo hexafluorophosphates was found to lead to the formation of halo enol phostones. Depending on the size of the heterocyclic compounds formed (6–8-membered compounds), endo or a mixture of endo and exo cyclization products were obtained.
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preparation of oxetanes by 4 endo trig electrophilic cyclisations of cinnamic alcohols
Tetrahedron Letters, 2001Co-Authors: Sébastien Albert, Sylvie Robin, Gerard RousseauAbstract:Abstract The reaction of substituted cinnamic alcohols with bis( sym -Collidine)bromine(I) hexafluorophosphate was examined. In general no oxetane was obtained when a substituent was fixed on the carboncarbon double bond. However, oxetanes were formed in high yields when two substituents were present in α of the alcohol function.
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bis sym Collidine bromine i hexafluorophosphate as oxidant
Tetrahedron Letters, 2000Co-Authors: Gerard Rousseau, Sylvie RobinAbstract:Abstract Primary and secondary alcohols in solution in methylene chloride are oxidised with bis( sym -Collidine)bromine(I) hexafluorophosphate in good yields to the carbonyl compounds. For secondary and tertiary alcohols in which one of the substituents is a 4-methoxyphenyl group the oxidation takes place by cleavage of the phenyl- sp 3 carbon bond and formation of bromoanisole and carbonyl compounds.
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Halogenation of Pyridinols using Bis(sym-Collidine)iodine(I) and Bis(sym-Collidine)bromine(I) hexafluorophosphate
Tetrahedron Letters, 1997Co-Authors: Gerard Rousseau, Sylvie RobinAbstract:Abstract Iodination and bromination of pyridinols was achieved by action of the title reagents in methylene chloride. © 1997 Elsevier Science Ltd.
R. S. Brown - One of the best experts on this subject based on the ideXlab platform.
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Bis(pyridine)-based bromonium ions. Molecular structures of bis(2,4,6-Collidine)bromonium perchlorate and bis(pyridine)bromonium triflate and the mechanism of the reactions of 1,2-bis(2'-pyridylethynyl)benzenebrominum triflate and bis(pyridine)bromon
The Journal of organic chemistry, 2003Co-Authors: Alexei A. Neverov, Helen Xiaomei Feng, Kristen Hamilton, R. S. BrownAbstract:1,2-Bis(2'-pyridylethynyl)benzenebromonium triflate (4) and bis(pyridine)bromonium triflate (5) have been prepared and the mechanism of their reaction with various acceptors including eight alkenes of various structure, Collidine, and Br- are reported. The reaction of 4 with neutral acceptors is second-order overall and involves a preequilibrium dissociation of the bidentate-bound Br+ to form an unstable monodentate open form (4-op), which reacts with all neutral acceptors at or near the diffusion limit. Br- reacts with 4 by a different mechanism involving a direct nucleophilic attack on the Br+. The reaction of 5 with acceptors proceeds by a dissociative mechanism to reversibly form an unstable intermediate (pyr-Br+), which reacts with 4-penten-1-ol, 4-pentenoic acid adamantylidineadamantane and cyclohexene with nearly the same selectivity. The crystal and molecular structures of bis(2,4,6-Collidine)bromonium perchlorate (2-ClO4) and 5 were determined by X-ray crystallography.
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mechanistic evaluation of the transfer of br from bis sym Collidine bromonium triflate to acceptor alkenes
Journal of Organic Chemistry, 1998Co-Authors: Alexei A. Neverov, R. S. BrownAbstract:The kinetics of the reaction of bis(sym-Collidine)bromonium triflate (2−Br+/OTf-) with adamantylideneadamantane (AdAd), 4-penten-1-ol (4), and cyclohexene has been investigated in 1,2-dichlorethane at 25 °C under a variety of conditions. The rates of all the reactions are shown to be depressed by added Collidine, indicating that the first step for all is a reversible dissociation of 2−Br+/OTf- into free Collidine and a reactive intermediate, coll−Br+, which is then captured by the alkene. The product of the reaction of AdAd with 2−Br+/OTf- is an AdAd:Br+−coll complex, while that of reaction of 4 with 2−Br+/OTf- is the cyclic ether 2-bromomethyltetrahydrofuran. The reaction with cyclohexene is more complex and involves at least two reversibly formed intermediates, suggested to be coll−Br+ and cyclohexene:Br+−coll, the latter being captured by attack of triflate to give trans-1-bromo-2-trifluoromethanesulfonylcyclohexane. Detailed kinetic analysis shows that the reactions of Collidine, AdAd, cyclohexene, an...