نتایج جستجو برای: alkenes
تعداد نتایج: 5720 فیلتر نتایج به سال:
A combination of an in situ generated chiral Cu(I) /DTBM-MeO-BIPHEP catalyst system and EtOK enabled the enantioselective SN 2'-type allylic cross-coupling between alkylborane reagents and γ,γ-disubstituted primary allyl chlorides with enantiocontrol at a useful level. The reaction generates a stereogenic quaternary carbon center having three sp(3) -alkyl groups and a vinyl group. This protocol...
SmI(2)/H(2)O reduces cyclic 1,3-diesters to 3-hydroxyacids with no over reduction. Furthermore, the reagent system is selective for cyclic 1,3-diesters over acyclic 1,3-diesters, and esters. Radicals formed by one-electron reduction of the ester carbonyl group have been exploited in intramolecular additions to alkenes. The ketal unit and the reaction temperature have a marked impact on the dias...
A new approach to ferrocenyl haloalkenes and bis-alkenes was elaborated. The key procedure involves copper catalyzed olefination of N-unsubstituted hydrazones, obtained from ferrocene-containing carbonyl compounds and hydrazine, with polyhaloalkanes. The procedure is simple, cheap and could be applied for the utilization of environmentally harmful polyhalocarbons. The cyclic voltammetry study o...
The first efficient and non-precious nanoparticle catalyst for alkene hydrosilylation with commercially relevant tertiary silanes has been developed. The nickel nanoparticle catalyst was prepared in situ from a simple nickel alkoxide precatalyst Ni(O(t) Bu)2 ⋅x KCl. The catalyst exhibits high activity for anti-Markovnikov hydrosilylation of unactivated terminal alkenes and isomerizing hydrosily...
90 A practical method of olefin epoxidation was developed by combining FeCl3·6H2O and 1methylimidazole in acetone using H2O2 as the terminal oxidant. This system showed very good reactivity toward epoxidation of both terminal and substituted alkenes. The use of tridentate and tetradentate amine-bis(phenolate) ligands as additives was also examined. Modest improvement in selectivity was achieved...
We report the use of an immobilised form of Candida antarctica lipase B, Novozym((R)) 435, in a preliminary investigation into the development of a continuous flow reactor capable of performing the chemo-enzymatic oxidation of alkenes in high yield and purity, utilising the commercially available oxidant hydrogen peroxide (100 volumes). Initial investigations focussed on the lipase-mediated oxi...
Three PEG-functionalized imidazolium salts L1-L3 were designed and prepared from commercially available materials via a simple method. Their corresponding water soluble Pd-NHC catalysts, in situ generated from the imidazolium salts L1-L3 and Na2PdCl4 in water, showed impressive catalytic activity for aqueous Mizoroki-Heck reactions. The kinetic study revealed that the Pd catalyst derived from t...
The first study on the reaction of C(+)-C-Se(-) 1,3-dipoles with electron-deficient alkenes and alkyne is reported. 2-Arylselenocarbamoylthiazolium inner salts, the unique thiazole carbene-derived C(+)-C-Se(-) 1,3-dipoles, reacted efficiently with methoxycarbonylallenes or dimethyl acetylenedicarboxylate to produce dihydroselenophenes or selenopheno[2,3-b]pyrazines, respectively, in high yields...
A method for cobalt-catalyzed, aminoquinoline-directed ortho-functionalization of sp(2) C-H bonds with alkenes has been developed. Reactions proceed at room temperature in trifluoroethanol solvent, use oxygen from air as an oxidant, and require Mn(OAc)3 as a cocatalyst. Benzoic, heteroaromatic, and acrylic acid aminoquinoline amides react with ethylene as well as mono- and disubstituted alkenes...
Highly selective allylborations of aldehydes using α,α-disubstituted allylic pinacol boronic esters.
α,α-Disubstituted allylic pinacol boronic esters undergo highly selective allylborations of aldehydes to give tetrasubstituted homoallylic alcohols with exceptional levels of anti-Z-selectivity (>20:1). The scope of the reaction includes both acyclic and cyclic allylic boronic esters which lead to acyclic and exocyclic tetrasubstituted homoallylic alcohols. The use of β-borylated allylic boroni...
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