Enantioselective Conjugate Addition of Aldehydes to Oxetane- and Azetidine-Containing Nitroolefins: An Entry to Spirocyclic Pyrrolidines.

Enantioselective amine-catalyzed conjugate additions of aldehydes to oxetane- and azetidine-containing nitroolefins afford γ-nitroaldehydes as key building blocks en route to spirocyclic oxetane/azetidine-pyrrolidines. The study provided insights into the stability and reactivity of these β,β-disubstituted nitroolefins and enabled the enantioselective synthesis of chiral oxetanes and azetidines in moderate-to-high yields and enantioselectivities. This approach expands synthetic access to medicinally relevant scaffolds and broadens the scope of enantioselective organocatalytic transformations.