Umsetzungen von 5‐Bromalkyliden‐3‐pyrrolin‐2‐onen, 1

Abstract

Die Titelverbindungen 1 setzen sich mit Natriummethylat unter Substitution zu 5-[(Z)-a-Methoxyalkyliden]-3-pyrrolin-2-onen 2 sowie, unter Ringerweiterung, zu 5-Hydroxy-2-pyridonen 3 um. Das Produktverhaltnis hangt von den Substituenten und der Art des Alkoholats ab. 2b ist ein Naturstoff-Analogon (,,Azafadyenolid"). Reactions of 5-Bromoalkylidene-3-pyrrolin-2-ones, 1The title compounds 1 react with sodium methoxide to give 5-[(Z)-a-methoxyalkylidene]-3-pyrrolin-2-ones 2 by substitution and to yield 5-hydroxy-2-pyridones 3 by ring enlargement. The relative amounts of the products depend on the substituents and the alkoxides used. 2b is an analog of a natural product ("azafadyenolide").Im Zuge unserer Untersuchungen iiber Tetramsauren (Pyrrolidin-2,4-dione) haben wir die Reaktivitat des Halogens in den Benzylidenverbindungen 1 untersucht. Beim Erhitzen von l a mit Natriummethylat auf 150°C erhalt man zwei bromfreie, isomere Substanzen. Hauptprodukt ist das erwartete methoxylierte Pyrrolinon 2 a. Wie bei analogen cyclischen P-Ketoestern ublich 2,3), tritt durch Erhitzen in wasserhaltigem Essigester Verseifung und Decarboxylierung ein; man isoliert die Tetramsaure 2d. Bei der Methylierung von 2a mit Diazomethan erhalt man als einziges Produkt den Methylether 2e. Entsprechend entsteht durch Methylierung von 2d der Ether 2b, der als ha-Analogon des Naturstoffs Fadyenolid4) von Interesse ist.

5-Arylidene-3-aryl-pyrrolidine-2,4-diones with Affinity to theN-Methyl-D-aspartate (Glycine Site) Receptor, Part I

“…Stereochemically different from the arylidene tetramic acids mentioned so far are the tetramic acids 9 and 10 [14] . The corresponding 3-aryl derivatives 13-15 were obtained via the diazoketones 11 and 12 (Scheme 2).…”

“…In some cases the configuration of the side chain of alkylidene tetramic acids has been established spectroscopically [14] . The O-methyl ethers of Z isomers showed a positive NOE effect between the methoxy and the neighboring vinyl protons.…”

“…The acetyl NMR signals for the minor components were found at 2.4 ppm, corresponding to the E isomers 22b or 23b, respectively, since a relative upfield shift of the acetyl group absorption was to be expected for the Z isomer due to the shielding effect of the aromatic electrons. In order to control this method, we have prepared the O-acetate 24a from the benzylidene tetramic acid 4a whose Z configuration was previously established by NOE experiments [14] . The acetyl signal of 24a showed up at 2.39 ppm in the 1 H NMR spectrum.…”

“…To a solution of 0.43g (2 mmol) of compound 10 [14] in 20 ml CHCl3 were added 1 ml triethylamine and 1 ml acetic anhydride. After stirring at room temperature for 12 h the volatile fraction was removed and the residue recrystallized from methanol.…”

“…1. The compound was prepared in the same manner as compound 22a from 0.53 g (2 mmol) of compound 9 [14] .…”