4,8-Ditoluoyl-1,5-dihydroxynaphthalene: Efficient synthesis of multi-gram quantities

ORGN 117

Daniel S. Tyson, Materials Division, Ohio Aerospace Institute and NASA Glenn Research Center, 21000 Brookpark Road, MS 49-1, Cleveland, OH 44135 and Michael A. Meador, Materials Division, NASA Glenn Research Center, 21000 Brookpark Road, MS 49-3, Cleveland, OH 44135.
4,8-Ditoluoyl-1,5-dihydroxynaphthalene was synthesized in quantitative yield from the corresponding methylenequinone via base-catalyzed hydration. The synthetic approach followed the well established method of methoxy protection of 1,5-dihydroxynaphthalene, acylation, then acid-catalyzed deprotection. The final transformation immediately forms the ring-closed methylenequinone, 6-toluoyl-2-(4-methyl)phenyloxynaphtho[bc]furan-5-one, allowing limited quantities of the substituted dihydroxynaphthalene to be collected (3% yield). Treatment of the methylenequinone with aqueous, alkaline solution gives the title compound in one step with a 99% yield, an improvement of 80% compared to the two step literature method for preparing 4,8-dibenzoyl-1,5-dihydroxynaphthalene. A thorough discussion of related compounds and the complete synthetic methodology will be presented.