No abstract

Functionalization of the indole benzene ring wasa chieved by using an organocatalytic enantioselective Friedel-Crafts alkylation/lactonization reactiono fh ydroxyindoles with av arietyo fs ubstituted methyleneoxindoles.T his reactionw as applicable to indoles substituted with the hydroxy group at different positions of the benzene ring, and the corresponding pyrrolodihydrocoumarins were obtained in moderate to high yields (37-99%) with high ste-reoselectivities (up to 99% ee and > 20:1 dr)i nm ost cases.Ascale-upr eactiona nd derivatization of the representativep roductsw ere also carriedo ut to investigate the usefulness of this protocol. Scheme 3. a) Gram-scale synthesisof5d.b)Derivatization of 3a.c )D erivatizationof5a.Scheme4.Reactionof4 -methoxyindole (15)w ith 1a.

An unprecedented protocol for the efficient and highly chemoselective alkylation of unprotected arylamines using alcohols catalyzed by B­(C6F5)3 has been developed. The reaction gives N-alkylated products and ortho C-alkylated products in different solvents in good chemoselectivities and yields. Control experiments and DFT calculations indicated that the borane underwent alcohol/arylamine exchange to ensure catalytic activity, and a possible mechanism involving a carbocation is proposed.

A highly enantioselective C2 Friedel-Crafts alkylation reaction of 3-substituted indoles to β,γ-unsaturated α-ketimino esters has been developed. This reaction was efficiently catalyzed by a chiral phosphoric acid catalyst. The corresponding C2-substituted indole derivatives, bearing an α-ketimino ester motif, were obtained in moderate to high yields (up to 93%) and with high enantioselectivities (up to >99% ee).