Synthesis of stable 2H-pyran-5-carboxylates via a catalyzed propargyl-claisen rearrangement/oxa-6π electrocyclization strategy

The application of easily accessed propargyl vinyl ethers for the synthesis of monocyclic 2H-pyrans was achieved. Under the reaction conditions, highly substituted heterocycles were obtained in moderate to excellent yields. The one-pot sequence proceeds via a Ag(I)-catalyzed propargyl-Claisen rearrangement, followed by a base-catalyzed isomerization, and 6 pi-oxaelectrocyclization, leading to the formation of stable 2H-pyrans.