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Piperazine als Modellsubstrat für Oxidationen
H. Möhrle 1, K. Azodi 2
Affiliations
Article Info
1 Institut für Pharmazeutische Chemie, Heinrich-Heine-Universität, Universitätsstraße 1, Düsseldorf, D-40225, Germany, Email: h.moehrle@uni-duesseldorf.de
2 Institut für Pharmazeutische Chemie, Heinrich-Heine-Universität, Düsseldorf, Germany
Abstract
Piperazin-Derivate verhalten sich bei der Oxidation mit Quecksilber(II)-EDTA ungewöhnlich. Wegen der reaktiven cyclischen Endiamin-Zwischenstufen als azaanaloge Reduktone und die durch Dehydrierung in die Seitenkette entstehenden Carbonylverbindungen resultiert eine große Polymerisationstendenz. 1-Benzylpiperazine 5a–d können in mittleren Ausbeuten in die Piperazin-2,3-dione 8a–d überführt werden. Aus 1-Benzhydrylpiperazin 11 entsteht ein Gemisch von Piperazin-2,3-dion 12 und Piperazin-3-on 13. Übersichtlicher verläuft die Umsetzung 1,4-bis-substituierter Piperazine aufgrund der Symmetrie und der bevorzugten Dehydrierungsrichtung in den Cyclus, so dass aus 15 und 19 die Dione 16 bzw. 20 in sehr guten Ausbeuten zugänglich sind. Ein Mechanismus für die Reaktionen wird formuliert.
Piperazines as model substrate for oxidations
Piperazine derivatives when being oxidized by mercury-EDTA behave unusually. Due to the reactive cyclic enediamine intermediates as aza-analogous reductones and to the carbonyl compounds resulting from dehydrogenation in the side chain, there exists a high tendency of polymerization. 1-Benzylpiperazines 5a–d generate the piperazine-2,3-diones 8a–d in medium yields. From 1-benzhydrylpiperazine 11 results a mixture of piperazine-2,3-dione 12 and piperazine-3-on 13. The 1,4-bis-substituted piperazines react more differently because of the symmetry and the preferred direction of the dehydrogenation into the cycle. Thus, from 15 and 19 the diones 16 and 20, respectively, were available in very good yields. A mechanism for the reactions is proposed.
Piperazines as model substrate for oxidations
Piperazine derivatives when being oxidized by mercury-EDTA behave unusually. Due to the reactive cyclic enediamine intermediates as aza-analogous reductones and to the carbonyl compounds resulting from dehydrogenation in the side chain, there exists a high tendency of polymerization. 1-Benzylpiperazines 5a–d generate the piperazine-2,3-diones 8a–d in medium yields. From 1-benzhydrylpiperazine 11 results a mixture of piperazine-2,3-dione 12 and piperazine-3-on 13. The 1,4-bis-substituted piperazines react more differently because of the symmetry and the preferred direction of the dehydrogenation into the cycle. Thus, from 15 and 19 the diones 16 and 20, respectively, were available in very good yields. A mechanism for the reactions is proposed.