Palladium-Catalyzed Asymmetric Decarboxylative Lactamization of γ-Methylidene-δ-valerolactones with Isocyanates: Conversion of Racemic Lactones to Enantioenriched Lactams
A palladium-catalyzed asymmetric decarboxylative reaction of racemic gamma-methylidene-delta-valerolactones with aryl isocyanates has been developed to give enantioenriched 3,3-disubstituted 2-piperidones. High enantioselectivity has been achieved by tuning the ester group on substrate and the substituents of phosphoramidite ligand.
Palladium-Catalyzed Synthesis of 4-Oxaspiro[2.4]heptanes via Central Attack of Oxygen Nucleophiles to π-Allylpalladium Intermediates
作者:Ryo Shintani、Tomoaki Ito、Tamio Hayashi
DOI:10.1021/ol300852v
日期:2012.5.4
cyclopropanation of γ-methylidene-δ-valerolactones with aromatic aldehydes has been developed to give 4-oxaspiro[2.4]heptanes with high selectivity. The site of nucleophilic attack to a π-allylpalladium intermediate has been controlled with a sterically demanding phosphine ligand. The course of the reaction is highly dependent on ligands and solvents, and selective formation of methylenetetrahydropyrans has