AgSbF6-Catalyzed Tandem Reaction of 2-Alkynylanilines with Cyclic Enynones: Efficient access to 3-Furo[3,2-c]chromenylindoles and Related Scaffolds

A simple, mild, catalytic and efficient method for the straightforward synthesis of an interesting class of a range of 2-aryl/alkyl-substituted-3-(2-aryl/alkyl-4H-furo[3,2-c]chromen-4-yl)-1H-indoles in good to high yields is reported for the first time. This atom-efficient method proceeds via AgSbF6-catalyzed one-pot sequential intramolecular hydroamination (C-N bond formation) of 2-alkynylanilines followed by Friedel-Crafts alkylation/oxa-cyclization (creation of new C-C and C-O bonds) reaction between in situ generated 2-substituted indoles and several cyclic enynones.