Indolo[2,1-b]quinazolin-6,12-dione (tryptanthrin) derivatives present important types of nitrogen-containing heterocyclic compounds which are useful intermediate products in organic synthesis and have potential pharmaceutical applications. The new ethyl 5-oxo-5-(((12-oxoindolo[2,1-b]quinazolin-6(12H)-ylidene)amino)oxy)pentanoate (Compound 2) was synthesized. Compound 2 is the first example a tr...