Search results for "addition"
showing 10 items of 933 documents
Verschiedenartige Additionsreaktionen von 2-Cyano-2-propylradikalen an p-Tolylmethacrylat und 4-Cyclohexylphenylmethacrylat
1976
Durch Umsetzung von p-Tolylmethacrylat oder 4-Cyclohexylphenylmethacrylat in stark verdunnter, siedender Benzollosung mit einem sehr grosen Uberschus an 2,2′-Azoisobutyronitril wurden die erwarteten Additionsprodukte mit 2-Cyano-2-propylradikalen (1) erhalten, namlich p-Tolyl- bzw. 4-Cyclohexylphenyl-[4-cyano-2-(2-cyano-2-propyl)-2,4-dimethyl]valerianat (3a bzw. 3b) mit rund 50% Ausbeute. Daneben wurden p-Tolyl- bzw. 4-Cyclohexylphenyl-(4-cyano-4-methyl-2-methylen)valerianat (4a bzw. 4b), p-Tolyl- bzw. 4-Cyclohexylphenyl-[4-cyano-2(2-cyano-2-methyl-1-propyl)-4-methyl]valerianat (5a bzw. 5b), p-Tolyl- bzw. 4-Cyclohexylphenyl-(4-cyano-2,4-dimethyl)valerianat (6a bzw. 6b) und p-Tolyl- bzw. 4-C…
ChemInform Abstract: Synthesis of 2-Isoxazolines: Enantioselective and Racemic Methods Based on Conjugate Additions of Oximes.
2011
Acidic anilinium salts catalyze the direct formation of racemic 2-isoxazolines from enals and oximes by means of consecutive oxime conjugate-addition and intramolecular oxime-transfer reaction.
ChemInform Abstract: Enantioselective Zinc-Mediated Conjugate Addition of Terminal Alkynes to Enones.
2013
Zinc for conjugate alkynylation: The enantioselective conjugate addition of terminal alkynes to 2-arylidene-1,3-diketones in the presence of diethylzinc and a catalytic amount of (R)-VANOL has been developed. The reaction can be applied to different aromatic and heteroaromatic alkynes and enones, giving the expected products in good yield and with enantiomeric excesses up to 91%. The products can be enantiomerically enriched up to 99% ee by crystallization (see scheme).
A new and versatile method for iodofunctionalization of 1,3-dienes
1986
Abstract We wish to report the reactions of conjugated dienes with I(py) 2 BF 4 . This simple and general method allows the regiospecific 1,2-addition of iodine and a nucleophile to terminal dienes and the 1,4-addition to internal dienes.
ChemInform Abstract: Enantioselective Addition of Nitromethane to 2-Acylpyridine N-Oxides. Expanding the Generation of Quaternary Stereocenters with …
2014
The direct asymmetric Henry reaction with prochiral ketones, leading to tertiary nitroaldols, is an elusive reaction so far limited to a reduced number of reactive substrates such as trifluoromethyl ketones or α-keto carbonyl compounds. Expanding the scope of this important reaction, the direct asymmetric addition of nitromethane to 2-acylpyridine N-oxides catalyzed by a BOX-Cu(II) complex to give the corresponding pyridine-derived tertiary nitroaldols having a quaternary stereogenic center with variable yields and good enantioselectivity, is described.
1,4-regioselective iodofunctionalizations of 1,3-butadiene
1988
Abstract Addition reactions of benzene and acetonitrile to 1,3-butadiene are described. This new iodofunctionalization process proceeds “via” iodonium ion-allylic cation equilibrium and gives regioselectively 1,4-adducts, which can be alternatively obtained by acid treatment of the 1,2-derivative 8 .
N-Heterocyclic Carbene Catalyzed [3+2] Cycloaddition of Enals with Masked Cinnamates for the Asymmetric One-Pot Synthesis of Adipic Acid Derivatives.
2017
A novel short entry to 3,4-disubstituted adipic acids has been developed by employing an asymmetric NHC-catalyzed [3+2] cycloaddition of enals with masked cinnammates in moderate to good yields and high stereoselectivities. The synthetic utility of the protocol was demonstrated by the basic conversion of the masked cyclopentanone intermediates to 3S,4S-disubstituted adipic acid precursors of pharmaceutically important gababutins.
New spectrophotometric procedure for determining cefotaxime based on derivatization with 1,2-naphthoquinone-4-sulphonate into solid-phase extraction …
1998
Cefotaxime was derivatised with 1,2-naphthoquinone-4-sulphonate (NQS), extracted into solid-phase cartridges (C18) and detected using a UV-visible detection system. Optimum conditions for this new procedure were: hydrogencarbonate-carbonate buffer, pH 10.5, 5-min reaction time at 25 degrees C and an NQS concentration of 7.1x10(-3) mol l(-1). The accuracy and the precision of the liquid-solid procedure were tested. The procedure was used to measure cefotaxime in pharmaceutical and urine samples. The results obtained were contrasted with those reported for a HPLC method for urine samples. The generalized H-point standard additions method was used to measure cefotaxime in urine samples.
Assessment of EVAR Complications using CIRSE Complication Classification System in the UK Tertiary Referral Centre: A ∼6-Year Retrospective Analysis …
2021
Purpose: To retrospectively analyse complications in endovascular aortic repair (EVAR) interventions and evaluate if the CIRSE (Cardiovascular and Interventional Radiological Society of Europe) complication classification system is appropriate as a standardized classification tool for EVAR patients. Materials and Methods: Demographic, procedural and complication data in 719 consecutive patients undergoing EVAR at one institution from January 2014 to October 2019 were retrospectively reviewed. Data (imaging reports, procedural reports, nurse notes, discharge summary reports) were collected consulting the electronic patient record system (EPR) of the hospital and cleaned and stored in a Micro…
Rapid Self-Hypnosis: A New Self-Hypnosis Method and Its Comparison with the Hypnotic Induction Profile (HIP)
2001
Despite its clinical importance, there are few systematic studies on the application of self-hypnosis. Rapid Self-Hypnosis (RSH) was created to provide a new procedure that is easy, comfortable, fosters alertness, and can be done covertly in everyday life. We present it as an alternative to the self-hypnosis version of the Hypnosis Induction Profile (HIP). Using a crossover design, we found in an experimental session that the RSH and the HIP produced comparable objective and subjective scores in the Barber Suggestibility Scale (BSS). However, as compared with the HIP, participants rated RSH as significantly more coherent, pleasant, faster and easier to learn, more likely to be used in every…