Highly Diastereo‐ and Enantioselective Synthesis of α‐Spiro‐δ‐lactams by an Organocascade Reaction

An asymmetric synthesis of α‐spiro‐δ‐lactams by an organocascade reaction of easily accessible starting materials has been accomplished. The catalytic sequence begins with enantioselective Michael addition of a β‐ketoamide to an α,β‐unsaturated aldehyde, catalyzed by a secondary amine catalyst, and is followed by hemiaminal annulation. Optically enantiopure compounds with three stereogenic centres are obtained in good yields and excellent selectivities (up to >20:1 dr and up to >99 % ee ).