Monodentate phosphoramidites; versatile ligands in catalytic asymmetric intramolecular Heck reactions
نویسندگان
چکیده
منابع مشابه
Phosphoramidites: marvellous ligands in catalytic asymmetric conjugate addition.
The development of an efficient catalytic system for enantioselective carbon-carbon bond formation by 1,4-addition of organometallic reagents (organolithium, Grignard, and organozinc reagents) to enones is a major challenge in organic synthesis. This Account presents the breakthrough realized in this field using chiral phosphoramidite ligands for copper-catalyzed dialkylzinc additions. Applicat...
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An efficient enantioselective intramolecular Heck reaction of cyclohexadienones, using readily available and modular TADDOL-based mono- and bidentate phosphoramidites as chiral ligands and not requiring any additives, has been developed. Excellent enantioselectivities up to 96% ee are reached for the first time in a Heck reaction with monodentate ligands.
متن کاملAsymmetric hydrogenation using monodentate phosphoramidite ligands.
Monodentate phosphoramidites are excellent ligands for Rh-catalyzed asymmetric hydrogenations of substituted olefins. Enantioselectivities between 95 and 99% were obtained in the asymmetric hydrogenation of protected alpha- and beta-dehydroamino acids and esters, itaconic acid and esters, aromatic enamides, aromatic enol esters, aromatic and aliphatic enol carbamates, and alpha-substituted cinn...
متن کاملCatalytic Asymmetric Intramolecular Pauson Khand and Pauson Khand Type - - - Reactions
One of the limitations of the PKR is the poor regioselectivity observed in intermolecular reactions where unsymmetrical alkynes and alkenes can give rise to mixtures of four constitutional isomers. Inherent regiocontrol of the intramolecular PKR of enynes 3 to form bicyclic cyclopentenones 4 (Scheme 1) makes this variant appealing and it has been actively investigated since its inception in 198...
متن کاملMonodentate, Supramolecular and Dynamic Phosphoramidite Ligands Based on Amino Acids in Asymmetric Hydrogenation Reactions Breuil, P.A.R
The electronic and steric effects as well as hydrogen bonds on the formation of the heteroligand complexes between monodentate amino acid based phosphoramidite and monodentate phosphine ligands were studied. Pure heterocomplex formation through the hydrogen bond between LEUPhos and a urea based phosphine is observed leading to highly active and selective catalyst. Substrate orientation through ...
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ژورنال
عنوان ژورنال: Dalton Trans.
سال: 2003
ISSN: 1477-9226,1477-9234
DOI: 10.1039/b300565h