Autoxidation of a sterically hindered phenanthrene-4,5-diol and conversion of the products into phenanthrenequinones

Abstract

1,3,6,8-Tetra-t-butylphenanthrene-4,5-diol (1) is surprisingly susceptible to autoxidation to the hydroperoxide (2), the crystal structure of which has been determined. This reaction is initiated by light. In turn, the hydroperoxide (2) undergoes acid-catalysed autoxidation to the bishydroperoxide (12). The conversion of these hydroperoxides into the quinones (14) and (15) is described, as well as the autoxidation of some related phenanthrols. The ease of autoxidation is attributed to severe steric crowding in the bay region.