Copper-catalyzed condensation of imines and α-diazo-β-dicarbonyl compounds : modular and regiocontrolled synthesis of multisubstituted pyrroles

• Main Authors: Tan, Wei Wen, Yoshikai, Naohiko
• Other Authors: School of Physical and Mathematical Sciences
• Format: Article
• Language: English
• Published: 2018
• Subjects: Condensation; Copper Catalyzed; DRNTU::Science::Chemistry
• Online Access: https://hdl.handle.net/10356/89964; http://hdl.handle.net/10220/46433
• Institution: Nanyang Technological University

In the presence of a copper(II) catalyst, enolizable imines bearing various N-substituents and α-diazo-β-ketoesters undergo denitrogenative and dehydrative condensation to afford highly substituted pyrroles in moderate to good yields with exclusive regioselectivity. The reaction likely involves nucleophilic addition of the imine nitrogen to a copper carbenoid, tautomerization of the resulting azomethine ylide to an α-enaminoketone, and a subsequent enamine–ketone cyclocondensation. With Yb(OTf)3 as a unique cocatalyst, α-diazo-β-diketones also participate in the same condensation reaction. The present reaction is applicable to acyclic, exocyclic, and endocyclic imines with tolerance of a broad range of functional groups and heterocyclic moieties, thus opening a new convenient route for the synthesis of the lamellarin family of natural products.