Synthesis of 1,6-dihydropyrrolo[2,3-g]indazoles using Larock indole annulation

The synthesis of 1,6-dihydropyrrolo[2,3-g]indazole derivatives is described. The indolic ring system is constructed via a Larock palladium-catalyzed annulation using terminal and internal alkynes. Additionally, when using internal alkynes for this reaction, we found that a directing effect on regioselectivity was mediated by the ester group of alkyl 3-substituted propiolate derivatives.