Highly regioselective and diastereodivergent aminomethylative annulation of dienyl alcohols enabled by a hydrogen-bonding assisting effect.

ABSTRACT

A ligand-controlled palladium-catalyzed highly regioselective and diastereodivergent aminomethylative annulation of dienyl alcohols with aminals has been established, which allows for producing either cis- or trans-disubstituted isochromans in good yields with complete regioselectivity and good to excellent diastereoselectivity. Moreover, the chiral cis-products were also obtained in good yields with up to 94% ee by using a chiral phosphinamide as the ligand. Mechanistic studies revealed that the hydroxyl group plays a key role in facilitating the Pd-catalyzed Heck insertion regioselectively taking place across the internal C[double bond, length as m-dash]C bond of conjugated dienes.