Palladium-Catalyzed Oxidative Annulation of Acrylic Acid and Amide with Alkynes: A Practical Route to Synthesize α-Pyrones and Pyridones
摘要:
A range of internal alkynes smoothly underwent palladium-catalyzed oxidative annulations with acrylic acid and amide to afford alpha-pyrones and pyridones in good to excellent yields with high regioselectivity. The usage of O-2 (1 atm) as a stoichiometric oxidant with H2O as the only byproduct under mild conditions makes this process more attractive and practical.
The dehydrogenative coupling of maleic acids with alkynes proceeds smoothly accompanied by decarboxylation under rhodium catalysis to produce variously substituted a-pyrone derivatives. The catalyst system is also applicable to the coupling with 1,3-diynes and alkenes.