Catalytic enantioselective addition of indoles to arylnitroalkenes: An effective route to enantiomerically enriched tryptamine precursors

A new valuable catalytic protocol for the preparation of synthetically useful β‐indolyl nitro compounds bearing benzhydryl stereocenters is presented. The combined use of catalytic amounts of a commercially available chiral [SalenAlCl] complex and pyridine allowed, for the Friedel–Crafts alkylation reaction of indoles with aromatic nitro‐olefins to be carried out in good yields and enantioselectivity (up to 63% ee). © 2005 Wiley‐Liss, Inc. Chirality 17:522–529, 2005.