نتایج جستجو برای: desymmetrization
تعداد نتایج: 310 فیلتر نتایج به سال:
The enzymatic β-C-H hydroxylation of the feedstock chemical isobutyric acid has enabled the asymmetric synthesis of a wide variety of polyketides. The analogous transition metal-catalyzed enantioselective β-C-H functionalization of isobutyric acid-derived substrates should provide a versatile method for constructing useful building blocks with enantioenriched α-chiral centers from this abundant...
Catalytic enantioselective desymmetrization of meso-2-substituted glycerols has been developed to secure a novel synthetic route to chiral tertiary alcohols. The transformation has been realized by monobenzoylation using benzoyl chloride and triethylamine in the presence of the imine ligand (25)-CuCl2 complex in THF at ambient temperature. The desymmetrization turned out to be greatly dependent...
Atroposelective transformations of (hetero)biaryls are classified into desymmetrization, kinetic resolution, dynamic and asymmetric transformation depending on the nature behavior starting material.
The catalytic asymmetric Michael addition/desymmetrization reaction of N-(2-t-butylphenyl)maleimides with unprotected 3-substituted-2-oxindoles was successfully realized using a chiral N,N'-dioxide-Sc(III) complex, leading to succinimides with two kinds of stereogenic elements—atom chirality and axial chirality—in up to 99% yield, 99% ee and >19 : 1 d.r.
The enantioselective synthesis of (-)-dysiherbaine (1) has been established with efficiency via a unique synthetic strategy involving the desymmetrization of 2-substituted glycerol to install a quaternary chiral carbon, which induces further stereochemistry in the bicyclic perhydrofuropyran through mercuriocyclization and epoxidation.
Ex-changing places: a highly enantioselective desymmetrization of 1,2-diols has been developed in which the catalyst utilizes reversible covalent bonding to the substrate to achieve both high selectivity and rate acceleration (see scheme, PMP=pentalmethylpiperidine, TBS=tert-butyldimethylsilyl). Induced intramolecularity is responsible for the enhanced rate, thus allowing the reaction to be per...
γ-Butyrobetaine hydroxylase (BBOX) is a 2-oxoglutarate dependent oxygenase that catalyzes the final hydroxylation step in the biosynthesis of carnitine. BBOX was shown to catalyze the oxidative desymmetrization of achiral N,N-dialkyl piperidine-4-carboxylates to give products with two or three stereogenic centers.
A carbene-catalyzed desymmetrization of prochiral bisphenol compounds bearing remote P-stereogenic centers is disclosed. The catalytic reactions can be performed on gram scales with 1 mol % N-heterocyclic carbene (NHC) catalyst, providing efficient access to enantiomerically enriched P-stereogenic phosphinates. The chiral phosphinates prepared with our method can find widespread applications as...
Access to P-chiral H-phosphinates via desymmetrization of hypophosphite esters was investigated. The use of chiral auxiliaries, chiral catalysts, and of a bulky prochiral group that could lead to kinetic resolution was explored. A chiral NMR assay for enantiomeric excess determination of H-phosphinates was developed. An asymmetric route to C-chiral H-phosphinates is also examined and an assay w...
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