Synthesis of Furans through Silver‐Catalyzed Propargyl–Claisen Rearrangement Followed by Cyclocondensation

Abstract

Abstract The generation of highly substituted furans from propargyl vinyl ethers bearing a free hydroxy group was investigated. In the presence of catalytic amounts of AgBF 4 , a formal [3,3] sigmatropic rearrangement takes place in the first stage of the sequence. The resulting allenyl carbonyl intermediates then undergo cyclocondensation, which upon double‐bond isomerization leads directly to the five‐membered heterocyclic products. This domino reaction allows the synthesis of various tri‐ and tetrasubstituted furan products; an example leading to pyrroles in an analogous way is also described.