Copper-Catalyzed Trifluoromethylation of Aliphatic N-Arylhydrazones:AConcise Synthetic Entry to 2-Trifluoromethylindoles from Simple Aldehydes
Résumé
Thec opper-catalyzed C(sp 2) À Ht rifluoro-methylation of N,N-disubstituted hydrazones using the Tognir eagent is demonstrated to proceed efficiently for aliphatic aldehyde-derived substrates. Thes uccess of the reactions relied on the choice of the N,N-diphenylamino group as the terminal hy-drazone amino group where N,N-dialkylamino groups were preferredf or (hetero)aromatic alde-hyde-derived substrates.I na ddition,t he trifluoro-methylated N-arylhydrazones are shownt ob eideal substrates for Fischer indole synthesis allowing as traightforward,t hree-step access to 2-trifluoro-methylindole derivatives from simplea ldehydes.