Nachbargruppenbeteiligung bei der Dehydrierung cyclischer Amine vom Typ o-substituierter Anilinderivate / Neighbourgroup Participation with the Dehydrogenation of Cyclic Amines of the o-Substituted Aniline Type

The 2-Aminobenzylalcohols la - c produced with mercury-edta dehydrogenation the lactams 6a - c; the pipecoline 2b yielded the benzoxazine 3b indicating the participation of the nucleophilic hydroxymethyl group. The 2-aminobenzaldehydes showed a different behaviour in dependence on the ring size of the amine part: 7a, b led - via intermediate reaction of the hemiaminal 9 with the electrophilic formyl function - to the lactams 11a, b, while 7c gave rise to the aminoaldehyde 12 as major product and similarly the pipecoline 15 to the aminoketone 16. From 2′-(4-morpholinyl)-acetophenone (22) were received the lactam 31 and the aminoethanol 32, both by a twofold dehydrogenation.