190517-01-2Relevant academic research and scientific papers
Palladium-mediated asymmetric synthesis of 3β,5β,7β-trihydroxycycloheptene derivatives
Yoshizaki, Hiroki,Yoshioka, Kumiko,Sato, Yoshihiro,Mori, Miwako
, p. 5433 - 5454 (2007/10/03)
Asymmetric alkylation of 3,5,7-trihydroxycycloheptene derivative 15 was developed using a palladium catalyst with chiral ligand. The reaction site of π-allylpalladium complex 18 is controlled by steric repulsion between the nuclcophile and the substituents on the cycloheptene ring. When 15b was reacted with lithium dimethyl malonate using a catalytic amount of [Pd(C3H5)Cl]2 in the presence of (S)-BINAPO in THF, alkylated product 17 was obtained in 71% yield with 42% ee. However, the reaction of 15b with a large nucleophile, diethyl 2-lithio-2-(2-propenyl)malonate, in the presence of [Pd(C3H5)Cl]2 and (S)-BINAP in THF gave alkylated product 21d in 41% yield with 94% ee. In a similar manner, the reaction of 15b with dimethyl 2-(3-butenyl)-2-lithiomalonate 5e gave 21e in 64% yield with 82% ee.
