PPh₃-KOBu^t–Mediated Cyclization Reaction of β-Ketoesters with Alkynyl Ketones: Synthesis of Functionalized 2-Pyrones

Abstract

Cyclization of alkynyl ketones with β-ketoesters mediated by PPh₃ and KOBu^t to synthesize 2-pyrone derivatives was systematically described. A variety of β-ketoesters reacted with alkynyl ketones to give functionalized 2-pyrones in moderate to good yields under mild conditions.

Keywords:

• Alkynyl ketone
• cyclization reaction
• β-ketoester
• 2-pyrone

ACKNOWLEDGMENTS

We are grateful to the National Natural Science Foundation of China (20772116) and the Tianjin Natural Science Foundation (09JCZDJC24400) for financial support.

Notes

^a Isolated yield.

^b At 0 °C.

^c At reflux.

^a Isolated yield.

^b Performed at 0 °C for 8 h.

^a Isolated yields.

^b Performed in CH₂Cl₂ in the presence of 75 mol% KOBu^t.

^c Performed in CH₂Cl₂ in the presence of 25 mol% KOBu^t.