THERMAL CONDENSATION OF INDOLES WITH TRIFLUOROACETALDEHYDE

Article abstract of DOI:10.1016/S0022-1139(00)82736-0

The title condensations provide the corresponding (1'-hydroxy-2',2',2'-trifluoroethyl)indoles.Indole itself, 1-methylindole and 2-methylindole gave 3-adducts in yields of 77percent, 49percent and 84percent, respectively. 3-Substituted indoles (3-methylindole, ethyl indole-3-acetate and indole-3-ethyl acetate) afforded 2-adducts in yields of 69percent, 21percent and 23percent, respectively.The indole adduct eliminates water at 137 deg C to form a transient 3-(trifluoromethylmethylene)indolenine, which reacts rapidly with nucleophiles including indole.