نتایج جستجو برای: grignard reagents
تعداد نتایج: 29282 فیلتر نتایج به سال:
New well-defined, paramagnetic nickel complexes have been prepared and characterized by X-ray crystallography. The complexes were found to be active for the cross-coupling of alkyl electrophiles (especially ethyl 2-bromobutyrate) with alkyl Grignard reagents. The ligand architecture in these new complexes could potentially be rendered chiral, opening up future possibilities for performing asymm...
A cross-coupling reaction between alkyl bromides and chlorides and various Grignard reagents was carried out in the presence of commercially available copper or copper oxide nanoparticles as a catalyst and an alkyne additive. The catalytic system shows high activity, a broad scope, and good functional group tolerance.
Large asymmetric amplification originating from solubility differences between the enantiopure and the racemic catalyst is observed in the addition of Grignard reagents to enones. This behaviour is not reaction or catalyst specific and is observed for metal complexes of a variety of chiral diphosphine ligands, extensively used in asymmetric catalysis.
The first asymmetric total synthesis of fumimycin was accomplished. As a key step, a 1,2-addition of methyl Grignard reagents to ketimines with quinine as additive was employed. The absolute configuration of (+)-fumimycin was determined by CD-spectroscopy combined with time-dependent density functional calculations.
An easy route to synthetic analogues of radicamine B, codonopsine and codonopsinine from D-mannitol.
A general strategy for the synthesis of analogues of radicamine B has been carried out from D-mannitol. This method has been further extended to the synthesis of analogues of codonopsine and codonopsinine using appropriate Grignard reagents. The hence obtained molecules have been tested against various commercially available glycosidases and found to act as moderate to good inhibitors.
An unusual and novel reaction of α-alkoxyphosphonium salts, generated from O,O-acetals and Ph(3)P, with Grignard reagents under an O(2) atmosphere afforded alcohols in moderate to high yields. It was clarified by isotopic labelling experiments that the reaction proceeded via a novel radical pathway.
Highly enantioselective synthesis of chiral chromenes and tetrahydroquinolines is achieved by combining asymmetric copper-catalyzed allylic substitution with Grignard reagents and an efficient intramolecular Heck reaction. Moreover, the exocyclic double bond formed in the cyclisation was subjected to RCM, hydroboration and hydrogenation illuminating the synthetic versatility of these heterocycles.
An iron-catalysed, hydride-mediated reductive cross-coupling reaction has been developed for the preparation of alkanes. Using a bench-stable iron(II) pre-catalyst, reductive cross-coupling of vinyl iodides, bromides and chlorides with aryl- and alkyl Grignard reagents successfully gave the products of formal sp(3)-sp(3) cross-coupling reactions.
One-pot stereoselective synthesis of bromohydrins as a useful chiral building block was achieved by the reaction of Grignard reagents with optically active α-bromoaldehydes, which were in situ generated by direct asymmetric bromination of aldehydes catalyzed by a binaphthyl-based secondary amine (S)-3.
The widely available carbonyl compounds react with Grignard reagents in the presence of diethyl phosphite to give the corresponding olefins in good to excellent yields: A range of conjugated dienes, terminal olefins, multisubstituted-alkenes and conjugated enynes could be readily obtained by the method in mild conditions.
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