نتایج جستجو برای: asymmetric transformation
تعداد نتایج: 285010 فیلتر نتایج به سال:
An efficient organocatalytic asymmetric [3 + 2] cycloaddition reaction between 3-substituted methylenebenzofuranone derivatives and diverse Morita-Baylis-Hillman carbonates to provide complex polysubstituted spirocyclopentenebenzofuranone scaffolds in a single step is reported. C2-symmetric phospholanes were efficient nucleophilic catalysts of this transformation under mild conditions, providin...
Naphthamides derived from L-proline, which exist as a mixture of several diastereomers in solution, converged to single diastereomer by crystallization, and the conformational transformation was controlled after the crystals were dissolved in the solvent at low temperature, where the frozen conformation was retained long enough for subsequent asymmetric reaction.
We report a catalytic asymmetric total synthesis of the ascidian natural product perophoramidine. The synthesis employs a molybdenum-catalyzed asymmetric allylic alkylation of an oxindole nucleophile and a monosubstituted allylic electrophile as a key asymmetric step. The enantioenriched oxindole product from this transformation contains vicinal quaternary and tertiary stereocenters, and is obt...
One of the most important applications of the Asymmetric Hamiltonian Path Problem is in scheduling. In this paper we describe a variant of this problem, and develop both a mathematical programming formulation and simple metaheuristics for solving it. The formulation is based on a transformation of the input data, in such a way that a standard mathematical programming model for the Asymmetric Tr...
A zinc-ProPhenol-catalyzed direct asymmetric aldol reaction between glycine Schiff bases and aldehydes is reported. The design and synthesis of new ProPhenol ligands bearing 2,5-trans-disubstituted pyrrolidines was essential for the success of this process. The transformation operates at room temperature and affords syn β-hydroxy-α-amino esters in high yields with good to excellent levels of di...
In this communication, we report a composite macroporous hydrogel sheet that can rapidly transform into multiple 3D shapes in response to near-infrared (NIR) light on demand. The transformation relies on the photo-thermal-induced asymmetric shrinking of the hydrogel material, which is further verified by finite element modeling.
We present an asymmetric q-Painlevé equation. We will derive this using q-orthogonal polynomials with respect to generalized Freud weights: their recurrence coefficients will obey this q-Painlevé equation (up to a simple transformation). We will show a stable method of computing a special solution which gives the recurrence coefficients. We establish a connection between the newfound equation a...
Here we show that simple and readily available chiral sulfinamide-olefins can display great catalytic activities and enantioselectivities in rhodium-catalyzed 1,4-addition reactions. This study represent the first example of chiral sulfur-based olefin ligand class for transition metal-catalyzed asymmetric transformation.
We report the chiral diene ligated rhodium-catalyzed dynamic kinetic asymmetric transformation (DYKAT) of racemic secondary allylic trichloroacetimidates with a variety of N-methyl anilines, providing allylic N-methyl arylamines in high yields, regioselectivity, and enantiomeric excess. The rhodium-catalyzed DYKAT method addresses limitations previously associated with this particular class of ...
Butane-2,3-dione was activated towards nucleophilic addition of enecarbamates by a series of metal triflate complexes of a C2-symmetric diamine to give stereogenic, aldol-like, t-alcohols, a novel nickel(II) triflate complex was identified as a good catalyst for this asymmetric transformation, and an aquo nickel(II) complex was identified by XRD techniques.
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