Oxidative alkyl- and aryl-aminomercuriation of prop-2-ynyl alcohols. Synthesis of N-substituted α-iminoketones, α-di-imines, and α-aminopropionamidines

Abstract

Addition of primary aliphatic or aromatic amines to prop-2-ynol (1a), 1-phenylprop-2-ynol (5a), and oct-1-yn-3-ol (5b) in the presence of mercury(II) acetate leads to the precipitation of metallic mercury and the formation of the corresponding oxidation products. The oxidation of alcohols (5a) and (5b) in the presence of aromatic amines leads to α-aminoketones (6), whereas α-di-imines (7) are obtained from aliphatic amines. The reaction of alcohol (1a) and aliphatic amines yields α-di-imines (2); in contrast, α-di-imines (2) or α-aminoamidines (3) can, alternatively, be synthesized from aromatic amines. A mechanism involving the mercury(II) acetate-promoted addition of an amine to a carbon–carbon triple bond and an allylic oxidation, followed by the successive formation of α-iminoketones, α-di-imines, and α-aminoamidines is proposed.