Kooperativer Bibliotheksverbund

Berlin Brandenburg

and
and

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
Filter
  • Keglevich, György  (43)
Type of Medium
Language
Year
  • 1
    Language: English
    In: Tetrahedron Letters, 2011, Vol.52(21), pp.2744-2746
    Description: To clarify the inconsistent patent literature, the synthesis of Zoledronic and Risedronic acids involving a heterocyclic acetic acid (HAA), phosphorous acid (PA) and phosphorus trichloride (PC) as the reagents, and methanesulfonic acid as the solvent was studied in detail. It was found that the best synthesis can be accomplished at 80 °C using HAA and PC in a 1:3.1 molar ratio without any PA.
    Keywords: Rational Synthesis ; Optimization ; Dronic Acids ; Mechanism ; Chemistry
    ISSN: 0040-4039
    E-ISSN: 1873-3581
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 2
    Language: English
    In: Tetrahedron Letters, 04 May 2016, Vol.57(18), pp.1953-1957
    Description: A novel and efficient one-pot method has been developed for the synthesis of 1-substituted-3,4-dihydro-β-carbolines from tryptamine and a wide variety of carboxylic acids. The reaction was successfully applied to the synthesis of an important alkaloid harmalan as well as dihydro-eudistomin-U. This represents the first case in which 1-propanephosphonic acid cyclic anhydride (T3P®) has been used in the Bischler–Napieralski reaction. Unexpectedly it was observed that less than two equivalents of the T3P® reagent were sufficient for the two consecutive reactions.
    Keywords: Β-Carbolines ; Bischler–Napieralski Reaction ; Ring Closure ; One-Pot Synthesis ; T3p® ; Chemistry
    ISSN: 0040-4039
    E-ISSN: 1873-3581
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 3
    In: Synthesis, 2017, Vol.49(14)
    In: Synthesis, 2017, Vol.49(14), pp.3069-3083
    Keywords: Organophosphorus chemistry ; Microwave irradiation ; Phosphinates ; Kabachnik–fields reaction ; Alkylation, deoxygenation ; Hirao reaction
    ISSN: 0039-7881
    E-ISSN: 1437-210X
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 4
    Language: English
    In: Synlett, 2015, Vol.26(13)
    In: Synlett, 2015, Vol.26(13), pp.1847-1851
    Keywords: Phase-transfer catalysis ; Sugar-based crown ethers ; Asymmetric michael reactions ; Asymmetric cyclopropanations ; Enantioselectivity
    ISSN: 0936-5214
    E-ISSN: 1437-2096
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 5
    Language: English
    In: Tetrahedron, 05 July 2018, Vol.74(27), pp.3512-3526
    Description: Optically active cyclopropane derivatives were prepared by a novel, simple and green approach in high enantioselectivities using monosaccharide-based chiral crown ethers as phase transfer catalysts. The crown ethers having -glucopyranoside, -mannopyranoside and -altropyranoside units proved to be efficient catalyst in a few asymmetric phase transfer cyclopropanation reactions. The Michael-initiated ring closure (MIRC) reactions of diethyl bromomalonate with chalcones took place with complete diastereoselectivity and up to 99% ee. Using benzylidenemalononitrile, 2-arylidenemalononitriles, 2-benzylidene-1,3-indandione, substituted 2-benzylidene-1,3-indandiones, 2-arylidene-1,3-indandiones and 2-benzylidene-1,3-diphenyl-1,3-propanediones enantioselectivities up to 92%, 99%, 54% 93%, 89% and 72%, respectively, were achieved, in the presence of chiral lariat ethers derived from different monosaccharides. The absolute configuration of a cyclopropane diester product was determined by a combined CD spectroscopic and theoretical study.
    Keywords: Asymmetric Cyclopropanation ; Enantioselectivity ; Chiral Crown Ethers ; Phase Transfer Catalysis ; Chemistry
    ISSN: 0040-4020
    E-ISSN: 1464-5416
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 6
    Language: English
    In: Tetrahedron: Asymmetry, 15 October 2016, Vol.27(19), pp.960-972
    Description: A monoaza-15-crown-5 lariat ether derived from -glucose has been applied as a chiral phase-transfer catalyst in the Michael addition of diethyl, dimethyl, diisopropyl and dibenzyl malonates to enones under mild conditions to afford the adducts with good to excellent enantioselectivities. In the reaction of diethyl malonate with substituted -chalcone, the adducts with in enantioselectivities up to 89% ee. Among the reactions of substituted diethyl malonates, those of diethyl acetoxymalonate gave the best results (96% ee). The effect of the substituents of the chalcone was also investigated in reactions with diethyl acetoxymalonate. Among the chalcones substituted on the β-aryl, the -substituted compounds resulted in the highest enantioselectivities (88–97% ee). The substituents on the benzoyl aryl of chalcone caused a decrease in the enantioselectivity compared to the unsubstituted case. The adducts with furyl or thiophenyl substituents were formed with 〉99% ee. The glucose-based catalyst also proved to be effective in the cases of diisopropyl and dibenzyl acetoxymalonates (including ees up to 99% ee). The reactions of diethyl acetoxymalonate with cyclic enones gave the corresponding Michael adducts with enantioselectivities up to 83%. The absolute configuration of one of the new Michael adducts was determined by CD spectroscopy.
    Keywords: Chemistry
    ISSN: 0957-4166
    E-ISSN: 1362-511X
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 7
    Language: English
    In: Catalysts, 01 April 2015, Vol.5(2), pp.634-652
    Description: The solid–liquid phase C-alkylation of active methylene containing compounds with C=O or P=O functions under phase transfer catalysis or microwave conditions has been summarized in this minireview. The mono- and dialkylation of the methylene containing derivatives was investigated under microwave (MW) conditions. It was found that in many cases, there was no need to use phase transfer catalyst under MW conditions. Moreover, most of the reactions were carried out without any solvent. These results mean a serious green chemical advantage.
    Keywords: Compounds With Active Methylene Group ; C-Alkylation ; Microwave Irradiation ; Phase Transfer Catalysis ; Solvent-Free Reaction ; Green Synthesis ; Chemistry
    E-ISSN: 2073-4344
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 8
    Language: English
    In: Current Organic Synthesis, 2013, Vol.10(5), p.751-763
    Description: In this review, the relevance of the combined use of the microwave (MW) and phase transfer catalytic (PTC) techniques is studied within alkylations. In the solid-liquid phase C-alkylation of a series of simple CH-acidic compounds including P=O containing derivatives, in most cases there is no need to use a phase transfer catalyst, as MW promotes the reaction in itself. In the MW-assisted solid-liquid phase alkylation of phenol derivatives, the presence of an onium salt as a phase transfer catalyst ensures the predominance of the O-alkylation. In the absence of base and catalyst, the alkylation of phenol derivatives proved to be C-selective. As regards the MWpromoted solid-liquid phase alkylating esterification of phosphinic acids, the use of a phase transfer catalyst was beneficial in case of alkylating agents of normal reactivity. In MW-assisted N-alkylations there is no general rule for the relevance of a phase transfer catalyst. In the alkylation of phenotiazine, the presence of an onium salt promotes the formation of the N-alkylated product, while in the absence of catalyst, the C-alkylation is predominant. Most of the C- and O-alkylations was performed under solvent-free conditions.
    Keywords: Microwave Phase Transfer Catalysis C-Alkylation O-Alkylation N-Alkylation.
    ISSN: 1570-1794
    E-ISSN: 1875-6271
    Source: Bentham Science Publishers
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 9
    Language: English
    In: Phosphorus, Sulfur, and Silicon and the Related Elements, 01 January 2013, Vol.188(1-3), pp.39-41
    Description: Recent results obtained by our group on MW-assisted reactions, such as the alkylation of P˭O-functionalized CH-acidic compounds and the addition of dialkyl phosphites to α-ketophosphonates, are summarized together with the rational synthesis of hydroxy-methylene bis(phosphinic acids)....
    Keywords: Microwave ; Phosphonic Derivatives ; Alkylation ; Addition ; Chemistry
    ISSN: 1042-6507
    E-ISSN: 1563-5325
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 10
    Language: English
    In: New Journal of Chemistry, 2016, Vol.40(9), pp.7856-7865
    Description: New chiral monoaza-15-crown-5 type macrocycles annelated to methyl 4,6- O -benzylidene-- d -galactopyranoside have been synthesized. These crown ethers proved to be efficient catalysts in a few asymmetric reactions under mild phase transfer catalytic conditions. Michael adducts were formed with good to excellent enantioselectivities, so the addition of diethyl acetamidomalonate to -nitrostyrene took place with up to 92% ee, while the reaction of diethyl acetoxymalonate with chalcones proceeded with up to 99% ee. Using diethyl bromomalonate as the nucleophile, the chiral cyclopropane derivatives were formed in up to 99% ee with the addition to chalcone, in up to 78% ee in the reaction with benzylidene malononitrile, and in up to 76% ee in the reaction with 2-benzylidene-1,3-diphenyl-1,3-propanedione applying - d -galactoside-based crown ethers as the catalysts. In the Michael addition, the substituents of the chalcone had a considerable impact on the outcome of the reactions. Quantum chemical calculations have also been employed to evaluate the origin of the stereoselectivities.
    ISSN: 1144-0546
    E-ISSN: 1369-9261
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. Further information can be found on the KOBV privacy pages