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Double Axially Chiral Bisphosphorylimides Catalyzed Highly Enantioselective and Efficient Friedel–Crafts Reaction of Indoles with Imines



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Cool cats: 1,1′-Bi-2-naphthol and vaulted 3,3′-biphenanthrol-type bisphosphorylimides enabled the atom-economical and highly enantioselective Friedel–Crafts reaction between indoles and N-tosylimines with a low catalyst loading (see scheme). A very small amount of 4-(dimethylamino)pyridine (DMAP) suppressed the bisindole side product efficiently. The ortho-substituted aldimine substrates performed excellently in this catalytic system.