CuI/DMAP‐Catalyzed Oxidative Alkynylation of 7‐Azaindoles: Synthetic Scope and Mechanistic Studies

Abstract

An efficient and practical method for the N‐alkynylation of 7‐azaindoles has been established by using CuI/DMAP catalytic system at room temperature and in open air. This simple protocol has been successfully employed in the synthesis of a wide range of N‐alkynylated 7‐azaindoles with good yields. Also, this approach is well‐suited for large‐scale N‐alkynylation reactions. The designed N‐alkynylated 7‐azaindoles were further subjected to Cu‐/Ir‐catalyzed alkyne−azide cycloaddition (CuAAC/IrAAC) or “click” reaction for the rapid synthesis of 1,4‐/1,5 disubstituted 1,2,3‐triazole decorated 7‐azaindoles. A mechanistic study based on density functional theory (DFT) calculations and ultraviolet−visible (UV) spectroscopic studies revealed that the CuI and DMAP combination formed a [CuII(DMAP)2I2] species, which acts as an active catalyst. The DFT method was used to assess the energetic viability of an organometallic in the C‐N bond formation pathway originating from the [CuII(DMAP)2I2]complex. We expect that the newly designed Cu/DMAP/alkyne system will offer valuable insights into the field of Cu‐catalyzed transformations.