• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 2
  • 2
  • 2
  • Tagged with
  • 6
  • 6
  • 2
  • 2
  • 2
  • 2
  • 2
  • 2
  • 2
  • 2
  • 2
  • 2
  • 2
  • 2
  • 2
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Stereoselective Synthesis of 2,3-Diamino-2,3-dideoxy-β-D-mannosides via Anomeric O-Alkylation and Gold Catalyzed Synthesis of Glycosides Using S-But-3-ynyl Thiocarbonate Donors

Thapa, Prakash 27 September 2022 (has links)
No description available.
2

Stereoselective Synthesis of <i>β</i>-Mannosides and <i>β</i>-Mannosamines <i>via</i> Cs<sub>2</sub>CO<sub>3</sub>-Mediated Anomeric <i>O</i>-Alkylation.

Bhetuwal, Bishwa Raj January 2020 (has links)
No description available.
3

Síntese de potenciais intermediários de princípios ativos, buscando sempre o emprego de técnicas para proteção do meio ambiente / Synthesis of potential intermediaries active, always seeking the use of techniques to protect the environment

Leite, Juliana Aparecida dos Santos 03 December 2012 (has links)
A química verde, que tem a preocupação com o desenvolvimento de tecnologias e processos incapazes de causar poluição, tem sido citada cada vez mais em destaque, pela mídia, como mais uma das iniciativas para prevenção da poluição desenfreada. Neste estudo tem-se buscado a redução ou eliminação de solventes, adaptação dos sistemas reacionais para operação em temperatura ambiente e aumento do rendimento em processos de reações guiados pelos doze princípios da química verde. O objetivo deste trabalho consiste na síntese de intermediários de princípios ativos para uso industrial, através de processos de formação de oximas e oximas éteres. O trabalho foi dividido em duas etapas principais, preparação de oximas e preparação de oximas éteres. Na primeira preparou-se oximas através da reação de aldeídos (benzaldeído, furfuraldeído, salicilaldeído e p-anisaldeído) e cetonas (ciclopentanona, ciclohexanona, metil etil cetona, benzofenona e acetofenona) com cloreto de hidroxilamina, sem a utilização de solventes orgânicos e sem adição de água. Na segunda o objetivo foi preparar oximas éteres (O-butil benzaldeído oxima, O-butil furfuraldeído oxima, N-butoxi-(2-butoxifenil) metanimina, O-butil p-anisaldeído oxima, O-butil ciclohexanona oxima, O-butil ciclopentanona oxima e O-butil metil etil cetona oxima) a partir da alquilação de oximas utilizando um suporte sólido de KF/Al2O3 como catalisador. Todos os compostos foram caracterizados por RMN 13C (apt) e alguns por infravermelho e RMN 1H. / Green chemistry, which is concerned with the development of technologies and processes incapable of causing pollution, has been cited increasingly highlighted, by the media, as another of the initiatives to prevent pollution rampant. This study has sought a reduction or elimination of solvents, reaction to adjust the systems operating at room temperature and yield increase in reactive processes that are guided by the twelve principles of green chemistry. The objective of this work is the synthesis of active intermediates for industrial use, through processes of formation of oximes, oximes ethers. The work was divided into two phases, preparation of oximes and preparation of oximes ethers. In the first was prepared oximes by reaction of aldehydes (benzaldehyde, furfuraldeyde, salicylaldehyde and p-anisaldeyde) and ketones (cyclopentanone, cyclohexanone, methyl ethyl ketone, benzophenone and acetophenone) with hydroxylamine chloride without the use of organic solvents and without adding water. For the second was prepared oximes ethers (O-butyl benzaldheyde oxime, O-butyl furfuraldeyde oxime, N-butoxy-(2-butoxyphenyl) methanimine, O-butyl p-anisaldeyde oxime, O-butyl cyclohexanone oxime, O-butyl cyclopentanone oxime e O-butyl methyl ethyl ketone oxime) from the alkylation of oximes, using a solid support as catalyst KF/Al2O3. All compounds were characterized by 13C NMR (apt) and some infrared and 1H NMR.
4

Síntese de potenciais intermediários de princípios ativos, buscando sempre o emprego de técnicas para proteção do meio ambiente / Synthesis of potential intermediaries active, always seeking the use of techniques to protect the environment

Juliana Aparecida dos Santos Leite 03 December 2012 (has links)
A química verde, que tem a preocupação com o desenvolvimento de tecnologias e processos incapazes de causar poluição, tem sido citada cada vez mais em destaque, pela mídia, como mais uma das iniciativas para prevenção da poluição desenfreada. Neste estudo tem-se buscado a redução ou eliminação de solventes, adaptação dos sistemas reacionais para operação em temperatura ambiente e aumento do rendimento em processos de reações guiados pelos doze princípios da química verde. O objetivo deste trabalho consiste na síntese de intermediários de princípios ativos para uso industrial, através de processos de formação de oximas e oximas éteres. O trabalho foi dividido em duas etapas principais, preparação de oximas e preparação de oximas éteres. Na primeira preparou-se oximas através da reação de aldeídos (benzaldeído, furfuraldeído, salicilaldeído e p-anisaldeído) e cetonas (ciclopentanona, ciclohexanona, metil etil cetona, benzofenona e acetofenona) com cloreto de hidroxilamina, sem a utilização de solventes orgânicos e sem adição de água. Na segunda o objetivo foi preparar oximas éteres (O-butil benzaldeído oxima, O-butil furfuraldeído oxima, N-butoxi-(2-butoxifenil) metanimina, O-butil p-anisaldeído oxima, O-butil ciclohexanona oxima, O-butil ciclopentanona oxima e O-butil metil etil cetona oxima) a partir da alquilação de oximas utilizando um suporte sólido de KF/Al2O3 como catalisador. Todos os compostos foram caracterizados por RMN 13C (apt) e alguns por infravermelho e RMN 1H. / Green chemistry, which is concerned with the development of technologies and processes incapable of causing pollution, has been cited increasingly highlighted, by the media, as another of the initiatives to prevent pollution rampant. This study has sought a reduction or elimination of solvents, reaction to adjust the systems operating at room temperature and yield increase in reactive processes that are guided by the twelve principles of green chemistry. The objective of this work is the synthesis of active intermediates for industrial use, through processes of formation of oximes, oximes ethers. The work was divided into two phases, preparation of oximes and preparation of oximes ethers. In the first was prepared oximes by reaction of aldehydes (benzaldehyde, furfuraldeyde, salicylaldehyde and p-anisaldeyde) and ketones (cyclopentanone, cyclohexanone, methyl ethyl ketone, benzophenone and acetophenone) with hydroxylamine chloride without the use of organic solvents and without adding water. For the second was prepared oximes ethers (O-butyl benzaldheyde oxime, O-butyl furfuraldeyde oxime, N-butoxy-(2-butoxyphenyl) methanimine, O-butyl p-anisaldeyde oxime, O-butyl cyclohexanone oxime, O-butyl cyclopentanone oxime e O-butyl methyl ethyl ketone oxime) from the alkylation of oximes, using a solid support as catalyst KF/Al2O3. All compounds were characterized by 13C NMR (apt) and some infrared and 1H NMR.
5

Étude de la réactivité polyvalente des composés borés : de la fluoration électrophile à la synthèse d’amides par substitution nucléophile oxydante ; O-alkylation de dérivés phénoliques par substitution nucléophile : vers la mise au point d’un système éco-compatible / Versatile alkyl boronic reactivity : electrophilic fluorination and oxidative nucleophilic substitution for amide synthesis; O-Alkylation of phenols derivatives via a nucleophilic substitution

Cazorla, Clément 19 September 2011 (has links)
Ce travail a tout d’abord porté sur la réactivité des dérivés borés puis sur la réaction de O-alkylation des alcools aromatiques. L’utilisation des composés borés est en plein essor. Ils sont employés comme partenaires de couplage dans la réaction de Suzuki et les réactions d’additions [1,4] catalysées au rhodium pour la synthèse de molécules à hautes valeurs ajoutées. La polarisation de la liaison C-B induit le caractère nucléophile de ces composés. Cette réactivité a été exploitée pour la formation de liaisons C-F par fluoration électrophile. L’utilisation de Selectfluor® comme agent de fluoration aboutit à de bons rendements. Toutefois, la nucléophilie des composés alkylborés peut être inversée par substitution nucléophile oxydante. Ainsi, une méthode créant des liaisons C-N a pu être développée et a permis la synthèse d’amides à partir de nitriles et de sels de trifluoroborates de potassium en présence de Cu(OAc)2 et BF3.OEt2. En vue de l’importance de la chimie des éthers en synthèse organique, une méthode de préparation d’éthers aryliques a été développée au laboratoire. En partant d’un système stœchiométrique en trifluorure de bore, un système catalytique impliquant du triflate de cérium a été mis au point. Afin de répondre au mieux au concept de la chimie verte, un système catalytique hétérogène, sans solvant, a été décrit. Dans ce cas, le catalyseur employé est le Nafion® NR50, facilement recyclable, sans perte d’activité, et conduisant à de bons rendements avec les alcools aliphatiques et aromatiques. Des amines aromatiques secondaires peuvent également être préparées par cette méthode / This thesis describes the study of the reactivity of boron compounds and the O-alkylation of aromatic alcohols. The use of boronic derivatives increased considerably over the past decades. There are used as cross-coupling partners in the Suzuki reaction and for 1,4 rhodium-catalyzed addition reaction. The nucleophilic nature of these compounds was induced by the C-B bond polarization. This peculiar reactivity was studied for the C-F bond formation. The use of Selectfluor® as fluorinating agent leads to good yields. Nevertheless, the polarity of the C-B bond could be reversed by oxidative nucleophilic substitution. Thus, C–N bond could be formed from nitriles and potassium trifluoroborate salts promoted by Cu(OAc)2 in the presence of BF3.OEt2. Due to the importance of ether chemistry in organic synthesis, the O-alkylation of phenol derivatives was achieved in the laboratory. From a stoichiometric amount of Lewis acid, BF3.OEt2, a catalytic system was developed involving cerium triflate. Then, the focus on green chemistry led to use a heterogeneous catalyst. Where Nafion® NR50 appears as a suitable catalyst for the ether synthesis
6

Étude de la réactivité polyvalente des composés borés : de la fluoration électrophile à la synthèse d'amides par substitution nucléophile oxydante ; O-alkylation de dérivés phénoliques par substitution nucléophile : vers la mise au point d'un système éco-compatible

Cazorla, Clément 19 September 2011 (has links) (PDF)
Ce travail a tout d'abord porté sur la réactivité des dérivés borés puis sur la réaction de O-alkylation des alcools aromatiques. L'utilisation des composés borés est en plein essor. Ils sont employés comme partenaires de couplage dans la réaction de Suzuki et les réactions d'additions [1,4] catalysées au rhodium pour la synthèse de molécules à hautes valeurs ajoutées. La polarisation de la liaison C-B induit le caractère nucléophile de ces composés. Cette réactivité a été exploitée pour la formation de liaisons C-F par fluoration électrophile. L'utilisation de Selectfluor® comme agent de fluoration aboutit à de bons rendements. Toutefois, la nucléophilie des composés alkylborés peut être inversée par substitution nucléophile oxydante. Ainsi, une méthode créant des liaisons C-N a pu être développée et a permis la synthèse d'amides à partir de nitriles et de sels de trifluoroborates de potassium en présence de Cu(OAc)2 et BF3.OEt2. En vue de l'importance de la chimie des éthers en synthèse organique, une méthode de préparation d'éthers aryliques a été développée au laboratoire. En partant d'un système stœchiométrique en trifluorure de bore, un système catalytique impliquant du triflate de cérium a été mis au point. Afin de répondre au mieux au concept de la chimie verte, un système catalytique hétérogène, sans solvant, a été décrit. Dans ce cas, le catalyseur employé est le Nafion® NR50, facilement recyclable, sans perte d'activité, et conduisant à de bons rendements avec les alcools aliphatiques et aromatiques. Des amines aromatiques secondaires peuvent également être préparées par cette méthode

Page generated in 0.0827 seconds