Syntheses of Karwinaphthol B, 7-Methoxyeleutherin and Ventiloquinone E

Abstract

Acylation of the aryl nitromethane (35) with (9) gave the enone (45), which underwent cyclization to the tricyclic system (50). Thermally induced aromatization to the naphthopyran (51) and oxidation gave ventiloquinone E (3). On selective demethylation this gave ventiloquinone G methyl ether (54). Analogous chemistry based on the aryl nitromethane (57) gave tricyclic nitro compound (60). On thermally induced aromatization this gave karwinaphthol B (5), while application of the Nef reaction and concomitant oxidation gave 7-methoxyeleutherin (2).