Gold(I)-Catalyzed Indole Synthesis through Aza-Nazarov-Type Cyclization of α-Imino Gold Carbene Complexes and Arenes

Here we report a gold(I)-catalyzed and atom-economical ortho-N-indolyl-N-pyrazolylbenzene synthesis from 1,2,3-triazapentalenes and ynamides. The reaction occurs through the cleavage of the triazole ring and formation of a alpha-imino gold carbene intermediate. An aza-Nazarov-type cyclization with participation of an arene ring is involved. The reaction consists in a formal [4+1] heterocycloaddition where the four-carbon synthon is provided by the ynamide. Finally, indole synthesis could also be performed in a one-pot procedure from their 1-propargyl-1H-benzotrizaole precursors.

Automated summary

In this study, a gold(I)-catalyzed and atom-economical synthesis of ortho-N-indolyl-N-pyrazolylbenzene from 1,2,3-triazapentalenes and ynamides was reported. The reaction involves the cleavage of the triazole ring, formation of an alpha-imino gold carbene intermediate, and an aza-Nazarov-type cyclization with participation of an arene ring. The formal [4+1] heterocycloaddition reaction provides the four-carbon synthon from the ynamide, and indole synthesis can also be achieved in a one-pot procedure from their 1-propargyl-1H-benzotrizaole precursors.