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

Org Lett. 2006 Oct 12;8(21):4795-7. doi: 10.1021/ol061856x.

Abstract

[reaction: see text] 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 6pi-oxaelectrocyclization, leading to the formation of stable 2H-pyrans.