A stereoselective route to polysubstituted tetrahydroquinolines by benzotriazole-promoted condensation of aliphatic aldehydes and aromatic amines
By the promotion of benzotriazole (20 mol %), two molecules of anilines (or other arylamines) and two molecules of phenylacetaldehyde (or o-bromophenylacetaldehyde) condensed to give a series of 1,2,3,4-tetrahydroquinolines in a stereoselective manner. By the catalysis of SmI(2) or SmI(3), the N-(alpha-aminoalkyl)benzotriazoles derived from anilines and (R)-glyceraldehyde acetonide dissociated to the corresponding iminium and enamine species, which underwent asymmetric [4 + 2] cycloadditions to give optically active tetrahydroquinolines.
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