Synthetic routes to pyrroloiminoquinone alkaloids. A direct synthesis of makaluvamine C

Makaluvamine C is a pyrroloiminoquinone which has been isolated from marine sponges. This molecule has been synthesized in 13 steps from p-anisidine. The key steps in this synthesis include an intramolecular nucleophilic aromatic substitution mediated by potassium tert-butoxide, the selective reduction of a dinitro ester using catalytic hydrogenation, and the novel use of Fremy's salt to synthesize an iminoquinone from an amino phenol. The synthesis of makaluvamine C has been achieved from p-anisidine in 13.1% overall yield.