Prolinamide/PPTS-Catalyzed Hajos-Parrish Annulation: Efficient Approach to the Tricyclic Core of Cylindricine-Type Alkaloids.

A series of Wieland-Miescher ketone analogues bearing highly functionalized substituents are efficiently constructed in high enantioselectivities and good yields using catalytic amounts of prolinamide and PPTS. We have successfully utilized this reaction as a key step to synthesize the tricyclic core of cylindricine type alkaloids. [ABSTRACT FROM AUTHOR]