نتایج جستجو برای: chiral pyrrolidines
تعداد نتایج: 37647 فیلتر نتایج به سال:
One of the problems encountered in CE separations of basic compounds is the adsorption of analytes onto the negatively charged capillary wall which could lead to poor repeatability of migration time and peak area. Additionally, separation of enantiomers of chiral of basic drugs is commonly carried out in low pH buffer which contributes to strong ionic interaction of the cationic drug ions with ...
An efficient and unprecedented domino reaction of methyleneindolinones and N-tosyloxycarbamates has been developed to afford structurally complex and diverse bispirooxindoles in excellent yields (up to 98%) and spiroaziridine oxindoles in moderate to good yields (55-91%). Moreover, this protocol could also provide the unsymmetrical bispirooxindoles and various fused spirocyclic pyrrolidines in ...
We study the D → σπ, D → ρπ, B− → σπ−, B− → ρ0π− and B̄ → ρ±π∓ decays in a valence quark triangle model, incorporating chiral symmetries. We find a good agreement with recent experimental data for D → σπ and for D → ρπ. We point out that a long-distance contribution due to the axial vector a1 meson pole, calculated by using chiral symmetry, can be relevant to explain D → ρπ and for lowering the ...
synthesis of some new monocyclic β-lactams containing a quaternary carbon center via a [2+2]cycloaddition reaction is described. the reaction of achiral diphenyl ketene with chiral aldimines derivedfrom chiral 2, 3, 4, 6-tetra-o-acetyl-β-d-galactopyranosylamine, 2, 3, 4, 6-tetra-o-acetyl-β-dglucopyranosylamine and different benzaldehydes resulted in the formation of β-lactams as singlediastereo...
The loop algebra L(sl2) symmetry is found in a sector of the nilpotent BazhanovStroganov model. The Drinfeld polynomial of a L(sl2)-degenerate eigenspace of the model is equivalent to the polynomial [4, 5, 10–14] which characterizes a subspace with the Isinglike spectrum of the superintegrable chiral Potts model.
A critical objective for the continued advancement of the field of asymmetric catalysis is the design and implementation of novel activation modes that allow the invention of unprecedented transformations. Recently, our laboratory introduced a new mode of organocatalytic activation, termed (singly occupied molecular orbital) SOMO catalysis, that is founded upon the transient production of a 3π-...
Cobalt-porphyrin-catalysed intramolecular ring-closing C-H bond amination enables direct synthesis of various N-heterocycles from aliphatic azides. Pyrrolidines, oxazolidines, imidazolidines, isoindolines and tetrahydroisoquinoline can be obtained in good to excellent yields in a single reaction step with an air- and moisture-stable catalyst. Kinetic studies of the reaction in combination with ...
A mild and efficient palladium-catalyzed intermolecular aminoamidation and aminocyanation reaction of alkenes with a broad substrate scope has been developed. This cyclization process provides a valuable synthetic tool for obtaining substituted indolines, tetrahydroisoquinolines and pyrrolidines in good to excellent yields.
The asymmetric synthesis of substituted pyrrolidines has been accomplished using a novel organocatalytic cyclization reaction promoted by a Cinchona alkaloid based primary amine. The reaction proceeds smoothly yielding pyrrolidine-2,2-dicarboxylates after in situ diastereoselective reduction with high levels of enantioselection. Furthermore, these adducts could be easily transformed into N-prot...
3-Methyl vinyl aziridine undergoes a mild MgI2-promoted S(N)2' ring opening and concomitant cyclization with fumarate Michael acceptors to give trisubstituted pyrrolidines. The process is efficient and highly diastereoselective. This methodology has been applied to a concise asymmetric synthesis of (+)-allo-kainic acid.
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