The selective CH-functionalization of 2-substituted indoles is presented. Using bis (pinacolato) diboron (2) in the presence of iridium complexes, a novel catalytic mono- borylation is observed preferentially at the 7-position of the indole. This allows for an efficient synthesis of various 2, 7-di-and 2, 4, 7-trisubstituted indoles, which are otherwise difficult to access. The scope and limitation of the method is demonstrated.
[Paul, Sulagna; Chotana, Ghayoor A.; Holmes, Daniel; Reichle, Rebecca C.; Maleczka Jr., Robert E.; Smith III, Milton R. Journal of the American Chemical Society, 2006 , vol. 128, # 49 p. 15552 - 15553]
