M. Hussain, S. T. Toguem, R. Ahmad
Jul 22, 2011
Citations
0
Influential Citations
28
Citations
Journal
Tetrahedron
Abstract
Di-, tri- and tetra-alkenylindoles were prepared by palladium(0)-catalyzed Heck cross-coupling reactions of di-, tri- and tetrabromo-N-methylindoles. The reactions were carried out at 90 °C using a novel biaryl monophosphine ligand developed by Buchwald and co-workers. 1,2-Dihydrocarbazoles were formed by a domino ‘twofold Heck/6π-electrocyclization’ when the reaction was carried out at higher temperature. The regioselectivity of the Heck reaction of 2,3,6-tribromo-N-methylindoles was in favour of carbon atoms C-2 and C-3. The 1,2-dihydrocarbazoles were transformed, by Pd/C-catalyzed dehydrogenation, into the corresponding carbazoles in high yield.