A New Approach to Axially Chiral Bipyridine N,N'-Dioxides Bearing Aromatic Substituents and their Use for Catalytic Asymmetric Allylation of Aldehydes with Allyl(trichloro)silane

摘要

Palladium-catalyzed cross-coupling of bi-pyridine N,N'-dioxide 6,6'-dichloride (R_(nap),R_(pyr))-l with the aryl Grignard reagents opened a new approach to axially chiral bipyridine N,N'-dioxides (R)-2 bearing a variety of aryl groups at the 6 and 6' positions.One of the N,N'-dioxides (R)-2d which is substituted with 3,5-dimethyl-4-methoxy groups was found to be highly catalytically active and enantioselective for the asymmetric allylation of aldehydes with allyl(trichloro)silane.The allylation took place with 0.01-0.1 mol % of (R)-2d giving homoallyl alcohols of up to 94% ee.