A domino synthetic strategy leading to two-carbon-tethered fused acridine/indole pairs and fused acridine derivatives.

A series of new poly-functionalized two-carbon-tethered fused acridine/indole pairs were synthesized via Brønsted acid-promoted domino reactions between indoline-2,3-dione and C(2)-tethered indol-3-yl enaminones. The reactions were further expanded to prepare C-tethered fused acridine/pyridine pairs, N-substituted amino acids, N-cyclopropyl and N-aryl substituted fused acridine derivatives, as well as bis-furan-3-yl-substituted indoles. During these reaction processes, the domino construction of a fused acridine skeleton with concomitant formation of two new rings was readily achieved in a one-pot operation. The procedures are facile, avoiding time-consuming and costly syntheses, tedious work-up and purification of precursors.