Enedione-Functionalized Macrocycles via Oxidative Ring Opening of Furans

Article abstract of DOI:10.1021/jo00334a007

A series of novel polyketo macrocycles was synthesized by oxidative ring opening of the cyclic furan-acetone tetramer 1 and hexamer 2.Reaction of 1 with bromine in acetic acid-water gave the bis(trans-enedione) 3.The use of m-chloroperoxybenzoic acid allowed for the controlled oxidation of 1, giving ring-opened products with the cis-enedione configuration.Reaction using 4.2 equiv of the peracid with 1 gave the tetra-ring-opened octaketone 5 in good yield.Analogously, the hexamer 2, in the reaction with 6.3 equiv of peracid, gave the all-cis unsaturated dodecaketone6.By varying the stoichiometry of the peracid in its reaction with 1, the tri-ring-opened and the two regioisomeric di-ring-opened cis-enediones 7-9, respectively, were isolated.Acid-catalyzed isomerization of 8 and 9 gave the corresponding trans-enediones 3 and 10, respectively, and the structures of these cis and trans isomers were correlated by reduction of the enedione double bonds either by using zinc in acetic acid or by catalytic hydrogenation.The X-ray structures and UV-vis spectra of 3 and 5 are discussed.