Synthesis of anti- and syn-diol epoxides of trans-3,4-dihydroxy-3,4-dihydrobenzo[ghi]fluoranthene: Model planar diol epoxides

We describe the preparation of anti- and syn-3,4-dihydroxy-5,5a-epoxy-3,4,5 ,5a-tetrahydrobenzo[ghi]fluoranthene (2 and 3) as model planar diol epoxide s. These compounds were synthesized by a dihydroarene method in 10 steps st arting from 4H-cyclopenta[def]phenanthrene. These are the first examples of diol epoxides in which a five-membered ring is fused to the saturated ring bearing an epoxide group, and they are the rigid analogues of the extensiv ely studied benzo[c]phenanthrene diol epoxides (5 and 6). In accord with ex pectation, H-1 NMR data indicated that the diol conformations of 2 and 3 ar e locked into diequatorial and diaxial conformations, respectively, and thu s are suitable for comparative DNA binding studies.