Enantioselective Synthesis of Highly Substituted Chromans by a Zinc(II)-Catalyzed Tandem Friedel–Crafts Alkylation/Michael Addition Reaction
Received: 12 December 2012
Accepted after revision: 20 January 2013
05 February 2013 (eFirst)
An enantioselective tandem Friedel–Crafts alkylation/ Michael addition reaction of 1-methylindoles with nitroolefin enoates catalyzed by a chiral tridentate bisoxazoline-Zn(II) complex has been described. This method provides an efficient route to highly substituted chromans in good isolated yields with high stereoselectivities (up to 95:5 dr and 91% ee).