Cyclic Aldimines as Superior Electrophiles for Cu-Catalyzed Decarboxylative Mannich Reaction of β‑Ketoacids with a Broad Scope and High Enantioselectivity

A novel Cu-catalyzed
enantioselective decarboxylative Mannich reaction
of cyclic aldimines with β-ketoacids is described. The cyclic
structure of these aldimines, in which the CN bond is constrained
in the Z geometry, appears to be important, allowing Mannich condensation
to proceed in high yields with excellent enantioselectivities. A chiral
chroman-4-amine was synthesized from the decarboxylative Mannich product
in several steps without loss of enantioselectivity.