The Ruthenium Complex Catalyzed <i>N</i>-Heterocyclization of Aminoarenes to Quinoline Derivatives Using Allylic Alcohols and Aliphatic Aldehydes

Abstract

Abstract Aminoarenes reacted with 2-propen-1-ol and 2-buten-1-ol at 180 °C to give quinoline derivatives in fairly good yields in the presence of a catalytic amount of a ruthenium complex. Dichlorotris(triphenylphosphine)ruthenium was the most effective catalyst. The aminoarenes with electron-releasing groups favored the formation of the quinolines. The N-heterocyclization also proceeded when aliphatic aldehydes were used in place of the allylic alcohols. The employment of allylic alcohols gave, however, higher yields in several cases. The reaction involves the isomerization of the allylic alcohols to the corresponding aldehydes. The aldehydes reacted with aminoarenes to give Schiff-base dimers which were then cyclized in the presence of the ruthenium complex to the quinolines. As a key intermediate in the reaction, the ortho-metallated species has been proposed.