Cycloisomerization of Conjugated Trienones and Isomeric 2H-Pyrans: Unified Strategy toward Cyclopenta[b]furans.

Conjugated trienones and isomeric 2H-pyrans were found to engage in a novel cycloisomerization cascade toward cyclopenta[b]furan derivatives. Knoevenagel chemistry and pericyclic reactions meet again to expand the polyene-carbonyl manifold.