Samarium Triflate as Mild and Efficient Catalyst for Aza-Diels–Alder Reaction: A Facile Synthesis of cis-Fused Pyrano- and Furanoquinolines

Abstract

Three-component coupling reactions of aldehydes, amines, and cyclic enol ethers have been carried out in the presence of samarium triflate to afford the corresponding pyrano and furanoquinolines in excellent yields with high endo-selectivity. The reaction conditions are mild and amenable to scale-up.

Keywords:

• Aldehydes
• amines
• hetero-Diels–Alder reaction
• tetrahydroquinolines

ACKNOWLEDGMENT

A. R. R. thanks the University Grants Commission, New Delhi, for the award of a fellowship.

Notes

^a All products were characterized by ¹H NMR, IR, and mass spectra.

^b Isolated and unoptimized yields.

^c cis/trans isomers were separated by column chromatography.