Total syntheses of the meta,meta-bridged biphenyls (±)-myricanol and myricanone, and of an isomeric biphenyl ether, a 14-oxa[7,1]metaparacyclophane

Abstract

The oxidative coupling of 1,7-bis(hydroxyphenyl)heptanoids (2a,b) has been investigated: C–C coupling to meta,meta-bridged biaryls was not observed, but with thallium tris(trifluoroacetate) C–O coupling occurred forming a 14-oxa[7,1]metaparacyclophane analogous to the natural phenols acerogenin-A and galeon. Intramolecular reductive coupling, using tetrakis(triphenylphosphine)nickel(0), of the bis-iodides (11a,b) derived from phenols (2a,b), leads, after deprotection, to the desired meta,meta-bridged biphenyls myricanone and (±)-myricanol, albeit in rather low yield. OO-Dimethylmyricanone and (±)-OO-dimethylmyricanol were similarly synthesized. Irradiation (254 nm) in alkaline ethanol of the bromides (11g,h) also induced aryl–aryl coupling to form dibenzylmyricanone and (±)-dibenzylmyricanol acetate respectively.