Iridium-Catalyzed Asymmetric Isomerization of Primary Allylic Alcohols
摘要:
AbstractNothing to sm(Ir)k at: Under appropriate reaction conditions, iridium hydride catalysts promote the isomerization of primary allylic alcohols. The best catalysts, like (R)‐1 (P green, O red, N blue, Ir yellow), deliver the desired chiral aldehydes with excellent enantioselectivity and good yields. Mechanistic hypotheses have been developed on the basis of preliminary investigations.magnified image
improved generation of chiral cationic iridium catalysts for the asymmetricisomerization of primaryallylicalcohols is disclosed. The design of these air‐stable complexes relied on the preliminary mechanistic information available, and on Charton analyses using two preceding generations of iridium catalysts developed for this highly challenging transformation. Sterically unbiased chiral aldehydes
Expanded scope for the iridium-catalyzed asymmetric isomerization of primary allylic alcohols using readily accessible second-generation catalysts
作者:Luca Mantilli、Clément Mazet
DOI:10.1039/b920342g
日期:——
A second generation of chiral (P,N)-iridium catalysts--readily accessible from inexpensive L-serine--displays expanded scope for the asymmetricisomerization of primaryallylicalcohols.
Efficient isomerization: The title reaction was catalyzed by the [RuCl2(S)‐tol‐binap}(R)‐dbapen}]/KOH system in ethanol at 25 °C (see scheme). A series of E‐ and Z‐configured aromatic and aliphatic allylic alcohols, including a simple primary alkyl‐substituted compound (E)‐3‐methyl‐2‐hepten‐1‐ol, were transformed into the chiral aldehydes with at least 99 % ee. dbapen=2‐dibutylamino‐1‐phenylethylamine
A method for producing, in a few simple steps, a specific optically active aldehyde represented by the general formula (1), in which * is an asymmetric carbon atom, includes asymmetrically isomerizing a specific allyl alcohol represented by the general formula (2) in the presence of a ruthenium complex and a base.
A method for producing, in a few simple steps, a specific optically active aldehyde represented by the general formula (1), in which * is an asymmetric carbon atom, includes asymmetrically isomerizing a specific allyl alcohol represented by the general formula (2) in the presence of a ruthenium complex and a base.