A convenient synthesis of 3,4-difunctionalized δ-carbolines

An efficient and direct preparation of functionalized δ-carbolines, via a ring closure reaction between the appropriate indole amine and a masked 1,3-dicarbonyl compound is described. This method afforded new 3-substituted δ-carbolines and these products were subjected to ortho-lithiation experiments. Various 3,4-disubstituted δ-carbolines were obtained in acceptable yields.