Synthesis of Arcyriarubin A and Arcyriaflavin A via Cross-Coupling of Indolylboronic Acid with Dibromomaleimides

Abstract

Arcyriarubin A was first isolated by Steglich in 1980; it is also the key intermediate in the synthesis of indolocarbazole compounds. A new synthetic approach to the natural products arcyriaflavin A and arcyriarubin A is described. The key step is a Suzuki cross-coupling reaction using indolylboronic acid as the starting material. The preparation of arcyriaflavin A was accomplished in eight steps from indole for a total yield of 21%.

Keywords:

• Arcyriaflavin A
• arcyriarubin A
• indolocarbazoles
• Suzuki coupling

Notes

^a Reaction conditions: solvent A, 15 ml: solvent B, 3 ml; base 2 ml; catalyst, 10 mol%; refluxing; 10 h.

^b Isolated yields.