Synihesis of 3-substituied indoles via a modified madeling reaction

Article abstract of DOI:10.1016/S0040-4020(01)86867-8

Anilides 4a-c,e-k, lla-d in which the amide function is benzylated, or silylated and having different electron-withdrawing groups (EWG) at the methyl methyl in the ortho position of the amide function, cyclize under the influence of potassium tert-butoxide to the corresponding indole derivatives 5a-c,e-k and 9a-d, respectively, under these conditions the chloroacetamides 4d,n and 11e are converted into the tetrahydroquinolines 6a,b and 12, respectively. Treatment of chloroacetamide 4m with KOt-Bu gave, in addition to starting material, indole 5m, tetrahydroquinoline 6c and 2(1H)-quinolinone 7. When 3-indolecarbonitrile 5a is treated with sodium in liquid amnonia debenzylation takes place, while after catalytic hydrogenation with 5% Pd/C the corresponding 2,3-dirnethylindole 8 is formed.