Iron/acetic acid mediated synthesis of 6,7-dihydrodibenzo[b,j][1,7]phenanthroline derivatives via intramolecular reductive cyclization

An efficient iron/acetic acid mediated intramolecular reductive cyclization protocol for the synthesis of novel 6,7-dihydrodibenzo[b,j][1,7]phenanthroline derivatives is described. In this two-step procedure, aldol addition and reductive cyclization methods are effectively utilized for the construction of C-C and C-N bonds. This highly efficient process proceeds under mild conditions, tolerates different functional groups, and provides various substituted 6,7-dihydrodibenzo[b,j][1,7]phenanthroline derivatives in good to excellent yields. In addition, various synthetic utilities of these derivatives are also described.