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Electrophilic Reagents (electrophilic + reagent)
Selected AbstractsHydroxy Derivatives of Diamantane, Triamantane, and [121]Tetramantane: Selective Preparation of Bis-Apical Derivatives,EUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 28 2007Natalie A. Fokina Abstract Functionalizations of diamantane, triamantane, and tetramantane with electrophilic reagents (Br2, nitric acid) lead to various apical and medial disubstituted products that were separated and characterized individually. The highly desirable and otherwise inaccessible thermodynamically more stable apical bis-derivatives were obtained with high preparative yields through acid catalyzed isomerizations. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007) [source] Divergent Reactivity of 2-Azetidinone-Tethered Allenols with Electrophilic Reagents: Controlled Ring Expansion versus SpirocyclizationADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 4 2010Benito Alcaide Abstract A dual reactivity of 2-azetidinone-tethered allenols may occur by judicious choice of the electrophilic reagents, namely halogenating versus selenating reagents. Using common substrates, structurally different compounds, namely tetramic acids (from N -bromosuccinimide) or spirocyclic seleno-,-lactams (from N -phenylselenophthalimide), can be readily synthesized by these divergent protocols. [source] Ferric Chloride Hexahydrate-Catalyzed Highly Regio- and Stereoselective Conjugate Addition Reaction of 2,3-Allenoates with Grignard Reagents: An Efficient Synthesis of ,,,-AlkenoatesADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 11-12 2009Guobi Chai Abstract Ferric chloride hexahydrate was shown to be an efficient catalyst for the conjugate addition of 2,3-allenoates with alkyl-, aryl-, or vinyl-Grignard reagents to synthesize polysubstituted ,,,-unsaturated alkenoates with high regio- and stereoselectivity. The in situ formed magnesium dienolate may readily react with different electrophilic reagents under different reaction conditions with or without a catalyst to construct an allylic quaternary carbon at the ,-position of the ester group and a stereocontrollable retention of the carbon-carbon double bond. [source] The factors that influence the elution order for the resolution of amino acids on vancomycin phase using the polar-organic mobile phases after their pre-column derivatization with electrophilic reagentsBIOMEDICAL CHROMATOGRAPHY, Issue 6 2005S. Chen Abstract A variety of amino acids were enantioresolved on a vancomycin bonded chiral phase using the polar-organic mobile phases after their pre-column derivatization with electrophilic reagents in alkaline medium. The resolution was highly dependent on the analyte's structure and was enhanced as the aromatic side-chain group on the skeleton of analyte for ,,, interaction with the chiral selector became available. The steric hindrance resulting from the bulky side-chain group on the analyte also affected the resolution. Elution reversal, not found on the teicoplanin phase under the same chromatographic conditions, was possible through altering the type of reagent used in the derivatizing reaction (e.g. 2,4-difluorophenylisothiocyanate to 2,4-difluorophenylisocyanate). It is believed that the steric hindrance, as a result of the bulky sulfur atom in reagents such as methylisothiocyanate and others examined in this study, was responsible for the reversed elution order. The bulkiness of the substituent on the aromatic ring of derivatizing reagents (i.e. 2,3- and 3,5-dichlorophenylisothiocyanate) was observed to affect the resolution and alter the elution order as well. Copyright © 2005 John Wiley & Sons, Ltd. [source] | ||||||||||