Synthesis of highly functionalized indeno[1,2-b]furans

DBU-Promoted Cascade Annulation of Nitroarylcyclopropane-1,1-dicarbonitriles and 3-Aryl-2-cyanoacrylates: An Access to Highly Functionalized Cyclopenta[b]furan Derivatives

“…In spite of the importance of the cyclopenta­[ b ]­furans, only a few methods were reported for the synthesis of these cyclopenta­[ b ]­furan derivatives. The existing methods include oxidative cyclization of o -cyclopentenylphenol derivatives, [2 + 2] cycloaddition oxidation sequence, iodine-catalyzed reaction of indandione/indanone and aldehydes, hypervalent-iodine-mediated direct dehydrogenative α,β′-bifunctionalization of β-ketoesters and β-diketones, lactonization of 2-substituted indanone, triphenylphosphine-mediated annulation from dialkyl acetylenedicarboxylates, Nazarov reactions of 2-furyl vinyl ketones and related enones, cobalt-catalyzed domino reaction between 2-bromoaryl aldehyde and dimethyl itaconate, ring-closing metathesis/atom-transfer ring closure strategy, acid-catalyzed double cyclization, and intramolecular carboxypalladation of alkynoic acids followed by intramolecular olefin insertion . Recently, Vitale and co-workers reported that few compounds containing cyclopenta­[ b ]­furan moiety were prepared through formal [3 + 2] cycloadditions of 2-nitrobenzofurans with vinylcyclopropanes in the presence of palladium(0) catalyst .…”