Enantioselective Construction of Polycyclic Chromanes through
Organocatalytic Multicomponent Quintuple Reaction via One-pot Sequential
Procedure
Abstract
An efficient and highly stereoselective synthetic method access to
polycyclic chromanes has been achieved through organocatalyzed
three-component reactions involving 2-hydroxycinnamaldehydes,
2-aminochalcones, and malononitrile as substrates. The reactions
underwent a quintuple process by
aza-Michael/Michael/Knoevenagel/oxa-Michael/aldol-type reaction in
sequence to give products bearing 3 new generated rings and 5 chiral
centers in moderate to quantitative yields with excellent
enantioselectivities. A novel retro-reaction mechanism was discovered in
the synthetic transformations of products.