Search results for "Adduct"
showing 10 items of 320 documents
Enzymatic esterification of bicyclic meso-diols derived from 1,4-bis(hydroxymethyl)furan. An enantioselective Diels–Alder reaction equivalent
1998
Abstract meso -Diols derived from the Diels–Alder adduct 1,4-bis(hydroxymethyl)furan/dimethyl acetylenedicarboxylate can be enantioselectively monoacetylated under CRL or PSL catalysis with very good yields and moderate to excellent ees. (+)-Monoacetates are always preferentially formed in the reactions catalyzed by CRL, and their (−)-enantiomers are the main products in the acetylations under PSL catalysis. Absolute configurations have been determined by X-ray analysis of a single crystal of an ( R )-α-methoxyphenylacetyl derivative.
Triazolopyridines. Part 11. Ylides derived from 2-Acylmethyltriazolopyridinium salts.
1991
Abstract Ylides derived from 2-acylmethyltriazolopyridinium salts (2a) -(2c) react with methyl or ethyl propiolate and with dimethyl acetylenedicarboxylate to give ylides (3a)–(3e), (6) or (7). In some cases 1:2 adducts are formed, shown to be the novel ylides (8a)–(8d); an X-ray diffraction confirms structure (8a).
Cycloaddition reactions. A new type of cycloadduct from a substituted 2-vinylthiophen and dmad
1987
Abstract Cycloaddition reactions between 2-(1-cyanoallyl)thiophen and the dienophiles diethyl azodicarboxylate, N-phenylmaleimide , methyl propiolate, and dimethyl acetylenedicarboxylate are reported. Products include simple benzo[b] thiophen carboxylates (13,19) and reduced derivatives (8,9,10,12,18), as a mixture of diastereoisomers, except in the adduct with diethyl azodicarboxylate. With dimethyl acetylenedicarboxylate a new type of tricyclic compound was also found (20).
ChemInform Abstract: Triazolopyridines. Part 11. Ylides Derived from 2- Acylmethyltriazolopyridinium Salts.
2010
Abstract Ylides derived from 2-acylmethyltriazolopyridinium salts (2a) -(2c) react with methyl or ethyl propiolate and with dimethyl acetylenedicarboxylate to give ylides (3a)–(3e), (6) or (7). In some cases 1:2 adducts are formed, shown to be the novel ylides (8a)–(8d); an X-ray diffraction confirms structure (8a).
ChemInform Abstract: Synthesis and Chemical Reactivity of 5-Methoxy-2-vinyl-4-azaindoles.
2010
Abstract 2-Vinyl-4-azaindoles are less reactive with dienophiles than 2-vinylindoles. 5-Methoxy-2-vinyl-4-azaindole 2a and its 1-methyl derivative 2a reacts with N-phenylmaleimide to yield cycloadducts only under vigorous conditions. 2b produces a cycloadduct with dimethyl acetylenedicarboxylate, while 2a yields a Michael-type adduct. Reactions with more reactive dienophiles gave only polymeric products.
ChemInform Abstract: Carbazole Synthesis via an in situ Trapping Strategy with Indolyl Enol Ethers.
2010
Indolyl enol ethers, generated from the alkoxy(indolyl)carbenium tetra- fluoroborates (1) by treatment with sodium hydride, can be trapped with dimethyl acetylenedicarboxylate or N-phenylmaleimide to furnish the se- lectively functionalized carbazoles (3), (4), (5), (9), (10), and (13). In addition, the biaryl derivatives (6) and (11) are produced by a ring- opening reaction of the primarily formed Diels-Alder adduct. In the case of the biaryl derivative (6), an X-ray crystal structure analysis yields valuable information on constitutions and configurations in the biaryl series. The phenomenon of atropisomerism is discussed for this compound
Synthesis and Chemical Reactivity of 5-Methoxy-2-vinyl-4-azaindoles
1997
Abstract 2-Vinyl-4-azaindoles are less reactive with dienophiles than 2-vinylindoles. 5-Methoxy-2-vinyl-4-azaindole 2a and its 1-methyl derivative 2a reacts with N-phenylmaleimide to yield cycloadducts only under vigorous conditions. 2b produces a cycloadduct with dimethyl acetylenedicarboxylate, while 2a yields a Michael-type adduct. Reactions with more reactive dienophiles gave only polymeric products.
Syntheses and catalytic oxotransfer activities of oxo molybdenum(vi) complexes of a new aminoalcohol phenolate ligand.
2017
The new aminoalcohol phenol 2,4-di-tert-butyl-6-(((2-hydroxy-2-phenylethyl)amino)methyl)phenol (H2L) was prepared by a facile solvent-free synthesis and used as a tridentate ligand for new cis-dioxomolybdenum(vi)(L) complexes. In the presence of a coordinating solvent (DMSO, MeOH, pyridine), the complexes crystallise as monomeric solvent adducts while in the absence of such molecules, a trimer with asymmetric Mo[double bond, length as m-dash]O→Mo bridges crystallises. The complexes can catalyse epoxidation of cis-cyclooctene and sulfoxidation of methyl-p-tolylsulfide, using tert-butyl hydroperoxide as oxidant.
The Pd3(dppm)3(CO)2+ Cluster: An Efficient Electrochemically Assisted Lewis Acid Catalyst for the Fluorination and Alcoholysis of Acyl Chlorides.
2002
The dicationic palladium cluster Pd3(dppm)3(CO)2+ (dppm = bis(diphenylphosphino)methane) reacts with acid chlorides RCOCl (R = n-C6H13, t-Bu, Ph) to afford quantitatively the chloride adduct Pd3(dppm)3(CO)(Cl)+ and the acyl cation RCO+ as the organic counterpart. The dicationic reactive cluster can be reformed by electrolyzing the chloride complex with a copper anode leaving CuCl as a byproduct. The combination of these two reactions provides an electrocatalytic way to form the acylium from the acid chloride. Indeed, in CH2Cl2, 0.2 M NBu4PF6, or NBu4BF4, the electrolysis of the acid chloride in the presence of a catalytic amount of the cluster (1%) gives in good yields the acid fluoride RCO…
Measurement of white wines resistance against oxidation by Electron Paramagnetic Resonance spectroscopy
2018
International audience; Free radical theory of aging hypothesizes that oxygen-derived radicals are responsible for the storage-related flavor instability in wine. In an optimal situation, a balanced-distribution exists between oxidants and antioxidants among wines intrinsic/extrinsic metabolites. Based on the kinetic study of POBN-1-hydroxyethyl spin adduct (POBN-1-HER) formation in wines initiated via the Fenton reaction, a novel tool based on EPR spin trapping methodology was developed to quantify wines resistance against oxidation. Antioxidant capacities of wines were evaluated according to POBN-1-HER maximum signal intensity (Imax POBN-1-HER) and rate formation (r(POBN-1-HER)) kinetic p…