Die «Zip»‐Reaktion: Eine neue Ringerweiterungsreaktion. Synthese von 17‐, 21‐ und 25‐gliedrigen Polyaminolactamen. 4. Mitteilung über Umamidierungsreaktionen

The Zip‐reaction: A New Method for the Synthesis of Macrocyclic Polyaminolactams The 21‐ and 25‐membered aminolactams 11 and 25 were synthesized from the 13‐membered lactam 4 . To introduce the ring enlargement unit (a propylamino group) 4 was N ‐alkylated using acrylonitrile and the resulting product hydrogenated. Repetition of this reaction sequence gave 3 , which was converted in the presence of base in 90% yield to the ring‐enlarged macrocyclic base 11 ( Scheme 2 ). In a similar but stepwise synthesis consisting of two separate ring‐enlargement reactions 4 was transformed to 11 via 13 ( Scheme 4 ). Introducing three ringenlargement units into 4 the 25‐membered aminolactam 25 was synthesized in 84% yield ( Scheme 5 ). The mechanism of the ring‐enlargement reaction is given in Scheme 3 . In comparison to a zip‐fastener or zipper this reaction is called “zipreaction”.