Diastereoselective Reductive Cyclization of Allene‐Tethered Ketoamines via Copper‐Catalyzed Cascade Carboboronation and Protodeborylation

Abstract

A copper‐catalyzed cascade process has been developed for the synthesis of 3‐hydroxypyrrolidine derivatives in a highly diastereoselective manner. The reaction proceeded via borylative allyl copper intermediate formation from allenes; the intermediate underwent intramolecular diastereoselective cyclization followed by cascade copper‐catalyzed protodeborylation, to give 3‐hydroxypyrrolidines. This method could be extended to the synthesis of six‐membered piperidine analogs. A series of control experiments were carried out to confirm the Cu‐catalyzed facile protodeborylation of borylated homoallylic alcohols at room temperature.