Enantio- and Regioselective Iridium-Catalyzed Allylic Hydroxylation
摘要:
The first enantioselective allylic hydroxylation to prepare branched allylic alcohols directly is described. Bicarbonate was used as nucleophile in conjunction with new single component Ir-catalysts, which are stable to air and water. Excellent regio- and enantioselectivities have been achieved with a representative set of substrates.
A new phosphoramiditeligand was used in the iridium-catalyzed allylicsubstitution reaction. This permitted high regio- and enantioselectivities on a wide variety of substrates and nucleophiles. Because of the stereospecificity of the reaction obtained by using branched substrates, a kinetic resolution reaction was attempted. The origin of the impressive efficiency of this ligand in terms of kinetics
A highly regioselective palladium-catalyzedallylic alkylation of fluorobis(phenylsulfonyl)methane has been studied. Using different allylic carbonates, a variety of terminal mono-fluoromethylated compounds were achieved in 85–99% yields with high regioselectivities.
Very Efficient Phosphoramidite Ligand for Asymmetric Iridium-Catalyzed Allylic Alkylation
作者:Alexandre Alexakis、Damien Polet
DOI:10.1021/ol048607y
日期:2004.9.1
[reaction: see text] Linear or branched allylic carbonates or acetates undergo enantioselective iridium-catalyzedallylic substitution with sodium malonate. The reaction is wide in scope and affords the branched product in high yield and with high regio- (up to >99:1) and enantioselectivity (up to 98%). Ten aromatic or aliphatic substrates were successfully tested.
Enantioselective Synthesis of Allylboronates Bearing a Tertiary or Quaternary B-Substituted Stereogenic Carbon by NHC-Cu-Catalyzed Substitution Reactions
作者:Aikomari Guzman-Martinez、Amir H. Hoveyda
DOI:10.1021/ja104254d
日期:2010.8.11
Allylic substitutions that afford alpha-substituted allylboronates bearing B-substituted tertiary or quaternary carbon stereogenic centers are presented. C-B bond-forming reactions, catalyzed by chiral bidentate Cu-NHC complexes, are performed in the presence of commercially available bis(pinacolato)diboron. Transformations proceed in high yield (up to >98%) and site selectivity (>98% S(N)2'), and
Regio- and Enantioselective <i>N</i>-Allylations of Imidazole, Benzimidazole, and Purine Heterocycles Catalyzed by Single-Component Metallacyclic Iridium Complexes
作者:Levi M. Stanley、John F. Hartwig
DOI:10.1021/ja902243s
日期:2009.7.1
Kinetic studies on the allylation of benzimidazole catalyzed by metallacyclic iridium-phosphoramidite complexes, in combination with studies on the deactivation of these catalysts in the presence of heterocyclic nucleophiles, provide insight into the effects of the structures of the phosphoramidite ligands on the stability of the metallacyclic catalysts. The data obtained from these studies have led to