Recyclable gold(I)-catalyzed oxidative cyclization of 1,4-diyn-3-ols leading to highly substituted 3-formylfurans

An efficient heterogeneous gold(I)-catalyzed cascade oxidation/1,2-alkynyl migration/cyclization reaction of 1,4-diyn-3-ols has been developed. The reaction proceeds effectively in toluene at room temperature by using 3 mol% of MCM-41-anchored sterically demanding NHC-gold(I) complex [MCM-41-IPrAuOTf] as catalyst and 3,5-dichloropyridine N-oxide as oxidant and offers a general and practical route for the synthesis of a wide variety of 3-formylfurans in good to excellent yields from readily accessible starting materials. This heterogenized gold(I) catalyst can be facilely recovered via a simple centrifugation process and reused more than six times without any significant loss of its catalytic efficiency.