A facile synthesis of antitumoral indeno[1,2-c]pyrazole-4-one by mild oxidation with molecular oxygen

An efficient, convenient, and general synthetic method for indeno[1,2-c]pyrazole-4-ones through oxidation of indenopyrazoles by treatment with a base and molecular oxygen is described, and a possible mechanism for the oxidation is proposed. The product indeno[1,2-c]pyrazole-4-ones were elaborated further by Suzuki coupling and Mitsunobu reaction.