L (+) Arabinose as a catalyst for efficient and simple synthesis of dibenzo [a, c] phenazine in ethanol

The dibenzo [a, c] phenazine core possesses a phenanthrene ring fused to pyrazine [1]. Phenanthrene derivatives (10a-d) were efficiently prepared in excellent yields and high purity via a one-step sequence [2, 3]. We investigated the possibility of formation dibenzo [a, c] phenazine via condensation of o-diaminobenzene with phenanthrenequinone in ethanol. This reaction is performed in the presence of L (+) Arabinose as a cheap and readily available catalyst at 70°C. A simple and highly efficient procedure for the synthesis of dibenzo [a, c] phenazine is reported (Scheme 1). This method offers the advantages of proceeding, neutral and mild conditions, environmental, lock of toxicity, short reaction time, giving high to excellent yields of the products and simple work-up.