Tandem Diels−Alder Cycloadditions of 2-Pyrone-5-acrylates for the Efficient Synthesis of Novel Tetracyclolactones

Readily prepared from the regioselective Pd-catalyzed coupling reactions of 3,5-dibromo-2-pyrone, 3-bromo-2-pyrone-5-carboxylates undergo tandem uninterrupted sequential
Diels−Alder cycloaddition reactions with allyl vinyl ethers
in a highly regio- and stereoselective fashion to provide a
series of novel tetracyclolactones in good yields.