InCl3-catalyzed asymmetric aza-Friedel–Crafts reaction of indoles with imines generated from O-pivaloylated β-d-galactosylamine

The highly diastereoselective InCl3-catalyzed aza-Friedel–Crafts reaction of substituted indoles with aldimines generated from Kunz’s amine was studied. The reaction afforded the desired product in good to high yields with up to >19:1 diastereoselective ratios. The O-pivaloylated β-d-galactosyl moiety could not be cleaved under the traditional acidic conditions. It was removed successfully after unmasking of the O-pivaloyl groups using MeOH/NaOMe and treatment with HOAc/H2O subsequently, to yield the 3-indolyl aryl methanamine derivatives in high optical purity.

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