The Nature of 9-Substituted 9,10-Dihydroanthracene Monoanions Formed by the Monoprotonation of Dianions and the Deprotonation of Dihydroaromatics

Article abstract of DOI:10.1021/jo00366a020

The production of monoanions of the type 9-R-10-metallo-9,10-dihydroanthracene and 9-R-9-metallo-9,10-dihydroanthracene is accomplished by two methods.Method A involves the addition of sodium metal to 9-R-anthracene in anhydrous ammonia/THF.Protonation of the dianion intermediate by ammonia produces a monoanion which persists.In method B, 9-R-9,10-dihydroanthracenes are deprotonated by n-butyllithium in THF.By method A, methylation produces a mixture of 9-R-10-methyl-9,10-dihydroanthracene and 9-R-9-methyl-9,10-dihydroanthracene with the latter predominanting in all cases (R= Me, Et, n-Bu, i-Pr, Bz, Ph).By method B, only the 9,10-isomers are produced (except for R = Ph).Mechanistic implications are discussed, and MNDO calculations are presented for both dianions and monoanions.