Pd-Catalyzed Domino Reaction of Tetrasubstituted Furans

Significance

Reported is the palladium-catalyzed two- or three-component reaction of 2-(1-alkynyl)-2-alken-1-ones with nucleophiles and/or allylic chlorides leading to 3,4-fused bicyclic 2,5-disubstituted furans and tetrasubstituted furans, respectively. Both reactions were well studied in terms of reaction optimization and substrate scope. The yields range from moderate to very good but failed when NuH is malononitrile or allylNHTs. The synthetic utility of the methodology was further shown by subjecting products from the three-component reaction (NuH = allyl alcohol, but-3-enol, pent-4-enol or hex-5-enol) to the RCM reaction, thus yielding 3,4-fused bicyclic furans with various ring sizes.