Novel synthetic approaches to the palmarumycin skeleton

Flexible Route to Palmarumycin CP1 and CP2 and CJ‐12.371 Methyl Ether

“…During our work, [38] a paper of Coutts et al [39] appeared, describing the synthesis of 10 by using an aromatic nucleophilic substitution of 4-fluoro-1-nitrobenzene (12) with 8-benzyloxy-1-hydroxynaphthalene (11) to afford benzyl ether 13 (Scheme 3). Hydrogenation of 13 afforded amine 14 and oxidation with manganese dioxide gave benzoquinone acetal 10.…”

“…Synthesis of benzoquinone acetal 10 according to Coutts et al [39] Unfortunately, Coutts et al could not prepare palmarumycin derivatives, because the decarboxylation of the corresponding 3-methoxy-2-pyrone adduct failed. For the Diels-Alder reaction of 10 with 3-methoxy-2-pyrone, high pressure had to be used.…”

“…The suspension was filtered to afford amino phenol 14 as a slightly brown solid (8.16 g, 65 %, ref. [39] 95 %). M.p.…”

“…The biaryl ether crystallized by addition of n-pentane/diethyl ether as a slightly yellow solid (30.43 g, 82 %, ref. [39] 75-85 %). M.p.…”

“…The suspension was filtered, the toluene was removed at reduced pressure, and the residue was purified by silica gel chromatography to yield benzoquinone acetal 10 as faintly yellow crystals (7.50 g, 75 %, ref. [39] 70-80 %). M.p.…”