New chiral phosphoramidites with an amide moiety were used for iridium-catalyzed asymmetric allylicalkylation reactions. The best results were obtained with a ligand bearing an oxazolidinone moiety. The reaction of cinnamyl acetate with diethyl sodiomalonate without the use of lithium chloride gave the branched product with 94% ee.
A chiralaldehyde is rationally combined with a Lewis acid and a transition metal for the first time to form a triple catalytic system. This cocatalytic system exhibits good catalytic activation and stereoselective-control abilities in the asymmetric α-allylation reaction of N-unprotected amino acid esters and allyl acetates. Optically active α,α-disubstituted α-amino acids (α-AAs) are generated in
Pd(II)-Catalyzed Dehydrogenative Olefination of Vinylic C–H Bonds with Allylic Esters: General and Selective Access to Linear 1,3-Butadienes
作者:Yuexia Zhang、Zili Cui、Zejiang Li、Zhong-Quan Liu
DOI:10.1021/ol300442w
日期:2012.4.6
dienes by Pd(II)-catalyzed direct olefination of unactivated alkenes with allylicesters and acrylates via vinylic C–H activation. Various aryl and heteroaryl alkenes as well as aliphatic alkenes all give the desired linear 1,3-butadienes with retention of the traditionalleavinggroups such as OAc and other carboxylic acid estergroups.