Dendritic oxazoline ligands in enantioselective palladium-catalyzed allylic alkylations.
First to fourth generation dendritic substituents based on 2,2-bis(hydroxymethyl)propionic acid and (1R,2S,5R)-menthoxyacetic acid were attached to 2-(hydroxymethyl)pyridinooxazoline and bis[4-(hydroxymethyl)oxazoline] compounds. The new ligands obtained were assessed in palladium-catalyzed allylic alkylations. The first type of ligands exhibited enantioselectivity similar to that of a benzoyl ester derivative, whereas the latter type of ligands afforded products with higher selectivity than the analogous benzoyl ester. The activity of the dendritic catalysts decreased with increasing generation.
Malkoch
Michael
M
Department of Fiber and Polymer Technology and Department of Chemistry, Organic Chemistry, Royal Institute of Technology, SE-100 44 Stockholm, Sweden.
Hallman
Kristina
K
Lutsenko
Serghey
S
Hult
Anders
A
Malmström
Eva
E
Moberg
Christina
C