CuI–Ionic Liquids as Efficient Reaction Media for the Synthesis of Pyran Skeleton via Domino Knoevenagel–Hetero–Diels–Alder Reaction with Unactivated Alkynes

Abstract

The article describes ionic liquids [bmim][NO₃] in the presence of 30% mol CuI as efficient media for the domino Knoevenagel–hetero–Diels–Alder reaction of o-propargyloxy benzaldehydes as unactivated terminal alkynes with some active methylene compounds. Short reaction time, easy workup, good to excellent yields, and mild conditions are advantages of this new media.

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GRAPHICAL ABSTRACT

Keywords:

• CuI
• domino Knoevenagel–hetero–Diels–Alder reaction
• ionic liquids
• pyran skeleton
• unactivated alkynes

ACKNOWLEDGMENTS

S. B. gratefully acknowledges the Alexander von Humboldt Foundation for the research fellowship. We also thank R. Gleiter for his invaluable comments.

Notes

^a All reactions were carried out using 20% mol of CuI.

^b All reactions were carried out using 40% mol of CuI.

^c The optimized mol% of CuI in ionic liquids as reaction media was 20%.

Dedicated to Prof. Mohammad Raouf Darvich on the occasion of his 70th birthday