Selective Halogenation of 4-Oxo-4,5,6,7-tetrahydroindoles to 5-Halo-4,5,6,7-tetrahydeoindoles with Copper(II) Halides

Halogenation of 4-0x0-4.5.6.7-tetrahydroindoles with copper(I1) bromide or coooerlI1) chloride gave selectively 5-halo-4-0x0-4,5,6,7-tetrahydroindoles, which were easily transformed to 4-hydroxyindoles by the action of lithium halide/lithium carbonate in dimethylformamide.One of attractive synthetic routes to 4-substituted indoles is to use 4-0x0-