Glycosylation of 2,3‐diphenylindole and derivatives — Synthesis of O‐, N‐, and C‐glycopyranosides

Abstract Reaction of different glycosyl donors with 5‐hydroxy‐N‐methyl‐2,3‐diphenylindole (1C) led only to O‐glycosylation (compounds 6a–c and 8c‐α,β). Depending on the O‐protection of the glycosyl donors (2a–c, 3b, 4c), the β‐products were obtained mainly or exclusively. The corresponding N‐unsubstituted indole 1B and donors 2b and 5a, respectively, also yielded only O‐glycosylated products (compounds 11b and 13a). Depending on the glycosyl donor (2a or 2c), the N‐unsubstituted 5‐methoxy‐2,3‐diphenylindole (1A) led to N‐ and/or C‐glycosides (compounds 16a, 14a‐α,β, and 14c‐α,β). The structures were assigned with the help of 1H‐NMR data of these products or their derivatives.