2-(Trifluoromethyl)quinolines from anilines: A novel mode of isomerization and cyclization

Deprotonation of N-ethylidene-tert-butylamine with lithium diisopropylamide and subsequent condensation with ethyl trifluoroacetate gives 4-tert-butylamino-1,1,1-trifluorobut-3-en-2-one. An exchange of the amino substituent occurs when the latter compound is treated with anilines under mildly acidic conditions. When heated in the presence of phosphoryl trichloride, the resulting 4-amino-1,1,1-trifluorobut-3-en-2-ones undergo an N --> ortho shift of the side chain followed by cyclization and dehydration to afford 2-(trifluoromethyl)quinolines.