Palladium-catalyzed synthesis of spiro[2.4]heptanes: ligand-dependent position control in the nucleophilic attack to a pi-allylpalladium intermediate.
A palladium-catalyzed intermolecular cycloaddition of gamma-methylidene-delta-valerolactones with electron-deficient olefins has been developed for the synthesis of spiro[2.4]heptanes with high selectivity through a nucleophilic ring closure to the central carbon of a pi-allylpalladium intermediate. It was found that the course of the reaction is dependent on the ligand employed, and selective [4 + 2] cycloadditions can also be achieved by the use of a bulky monophosphine ligand.
Shintani
Ryo
R
Department of Chemistry, Graduate School of Science, Kyoto University, Sakyo, Kyoto 606-8502, Japan. shintani@kuchem.kyoto-u.ac.jp
Park
Soyoung
S
Hayashi
Tamio
T