Efficient oxidative aromatization of 9,10-dihydroanthracenes with molecular oxygen catalyzed by ruthenium porphyrin complex

In the presence of a catalytic amount of a ruthenium porphyrin complex, various 9,10-dihydroanthracene derivatives were aromatized with molecular oxygen to the corresponding anthracenes. It was found that the addition of sulfuric acid accelerated the aromatization at room temperature under atmospheric pressure of oxygen to afford various anthracenes in high yields.