Über eine Umlagerung von N‐Methyl‐1,2‐dihydropapaverin mit verdünnten Säuren

Knabe, J.; Kubitz, J.

doi:10.1002/ardp.19642970302

Cited by 33 publications

(4 citation statements)

References 18 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…In 1963, Knabe and coworkers reported the stereospecific rearrangement of 1,2-dihydroisoquinolines under acidic conditions (Scheme 16) [38,39]. Initially, an anionic mechanism had been proposed [40,41,42] until Langhals and Rüchardt [43] reported evidence for a free radical chain reaction involving the addition of in situ generated benzylic radicals to iminium ions in 1984.…”

Section: Addition To Aliphatic Iminium Ionsmentioning

confidence: 99%

Radical Addition to Iminium Ions and Cationic Heterocycles

2014

View full text Add to dashboard Cite

Carbon-centered radicals represent highly useful reactive intermediates in organic synthesis. Their nucleophilic character is reflected by fast additions to electron deficient C=X double bonds as present in iminium ions or cationic heterocycles. This review covers diverse reactions of preformed or in situ-generated cationic substrates with various types of C-radicals, including alkyl, alkoxyalkyl, trifluoromethyl, aryl, acyl, carbamoyl, and alkoxycarbonyl species. Despite its high reactivity, the strong interaction of the radical's SOMO with the LUMO of the cation frequently results in a high regioselectivity. Intra-and intermolecular processes such as the Minisci reaction, the Porta reaction, and the Knabe rearrangement will be discussed along with transition metal and photoredox catalysis or electrochemical methods to generate the odd-electron species.

show abstract

Section: Addition To Aliphatic Iminium Ionsmentioning

confidence: 99%

Radical Addition to Iminium Ions and Cationic Heterocycles

2014

View full text Add to dashboard Cite

show abstract

“…1,4-Dihydroisochinolinium-Verbindungen konnten bisher mit Ausnahme der 4-Benzyliden-Derivate nicht isoliert werden. Sie wurden nur als Intermediate bei der Verschiebung der Doppelbindung in Dihydroisochinolinen aus der 3,4-in die 1,2-Position postuliert [9,10]. Auch die Benzyliden-Derivate, deren Stabilität auf der Konjugation der 2,3-Doppelbindung mit dem Benzylidenrest beruhen dürfte, isomerisieren unter dem Einfluss von Säuren oder Basen in der Wär-me zu den Isochinoliniumsalzen [11].…”

Section: Ergebnisse Und Diskussionunclassified

“…ol-1-on(9) a) Zu 0.50 g (2.3 mmol) 10 in 10 mL MeOH wird eine Lösung von 1.74 g (4.6 mmol) NaBH 4 in 50 mL MeOH getropft und der Ansatz 24 h bei RT analog Lit [24]. gerührt.…”

unclassified

Oxidation cyclischer α-Aminoketone / Oxidation of Cyclic α-Aminoketones

Möhrle

Rohn

2007

Zeitschrift Für Naturforschung B

View full text Add to dashboard Cite

The 1,2,3,4-tetrahydro-isoquinolin-4-one 4 reacts as an α-amino ketone with periodate to give various products, the major compound being 1-hydroxy-1,2-dihydro-3,4-isoquinolinedione 12. Upon stepwise oxidation with Hg(II)-EDTA the 4-hydroxyisoquinolinium ion 14 is detected as an intermediate and its further oxidation with periodate gives rise to an almost identical product spectrum. Because 12 represents a carbinolamide with an additional 4-carbonyl group, this type was examined first. Acid catalysis was used because the reactive species mostly are iminium ions. With cyclic 1,3-dicarbonyl compounds, 1-substituted derivatives 17a, b are formed. With linear species 1-substitution is also observed, but the tautomeric forms 19a -c are obtained. The stable enones 24a, b result from alkyl ketones by ready autoxidation of the primary products. Base catalysis induces a ring contraction of 12 to the hydroxycarboxylic acid 25. Reaction of 12 with aniline and phenylhydrazine yields the easily oxidizable 1-substitution products 28 and 31.

show abstract

“…It seemed unlikely in view of the work of Knabe ef al. (8), who showed that dilute acid treatment of this compound results in migration of the 1-homoveratryl group to the 3-position, rather than ring closure. Furthermore, Schermerhorn and Soine (I) had isolated argemonine earlier in a procedure scrupulously avoiding mineral acids.…”

Section: Argemoninementioning

confidence: 99%