Electronically diverse hexa-2,4-diyne-1,6-diols enable predictive switching between dibromocyclobutene/butafulvene and 5-vinyl-3(2H)-furanone synthesis. The latter are preferred for electron-poor substrates, and were further turned into fluorophores.
Diastereo- and enantioselective oxa-Nazarov cyclization-Michael addition of conjugated 1,2-diketones was achieved by using asymmetric binary-acid catalysis with chiral phosphoric acid and FeBr3.
Divergent approaches were developed to synthesize δ-valerolactones or furanones via a palladium or copper-catalyzed α-hydroxycyclopropanol ring opening cyclizations, respectively.
A novel photosensitizer-free, gold-catalyzed tandem cyclization of 2,3-allenamides with aryl diazonium salts under visible light. Solvent-controlled selectivity gives furanimines or furanones.
A halotrimethylsilane facilitated cycloketonization of γ-hydroxyl ynones is detailed for one-step synthesis of polysubstituted 3(2H)-furanone products.