Isolierung von (R)-(?)-Armepavin aus Rhamnus frangula L

Pailer, M.; Haslinger, Ernst

doi:10.1007/bf00904524

Cited by 6 publications

(1 citation statement)

References 16 publications

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“…The N -acyl-Pictet–Spengler cyclizations of appropriate pairs of the building blocks with TFA in dichloromethane at 0 °C for 19–90 h (TLC control) gave the desired racemic N -ethoxycarbonyl-1-benzyltetrahydroisoquinolines 5a – h with intact ethoxycarbonyl protection of the phenolic groups ( Table 2 ). Simultaneous phenol deprotection and reduction of the carbamate group (route A) to an N -methyl group was accomplished by lithium alanate reduction in THF under reflux to give the racemic forms of the alkaloids armepavine ( 2a ; from Rhamnus frangula [ 27 – 29 ]), laudanine ( 2c ; from Papaver somniferum [ 30 – 31 ]), pseudocodamine ( 2d ; metabolite of isoorientaline in Corydalis platycarpa makino cell species [ 32 ]), reticuline ( 2e ; from Papaver somniferum [ 33 ]), orientaline ( 2f ; from Cryptocarya amygdalina [ 34 – 35 ]), cinnamolaurine ( 3a ; from Cinnamomum sp. T.G.H.…”

Section: Resultsmentioning

confidence: 99%

The ethoxycarbonyl group as both activating and protective group in N-acyl-Pictet–Spengler reactions using methoxystyrenes. A short approach to racemic 1-benzyltetrahydroisoquinoline alkaloids

Keller

Sauvageot-Witzku

Geisslinger

et al. 2021

Beilstein J. Org. Chem.

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We present a systematic investigation on an improved variant of the N-acyl-Pictet–Spengler condensation for the synthesis of 1-benzyltetrahydroisoquinolines, based on our recently published synthesis of N-methylcoclaurine, exemplified by the total syntheses of 10 alkaloids in racemic form. Major advantages are a) using ω-methoxystyrenes as convenient alternatives to arylacetaldehydes, and b) using the ethoxycarbonyl residue for both activating the arylethylamine precursors for the cyclization reaction, and, as a significant extension, also as protective group for phenolic residues. After ring closure, the ethoxycarbonyl-protected phenols are deprotected simultaneously with the further processing of the carbamate group, either following route A (lithium alanate reduction) to give N-methylated phenolic products, or following route B (treatment with excess methyllithium) to give the corresponding alkaloids with free N–H function. This dual use of the ethoxycarbonyl group shortens the synthetic routes to hydroxylated 1-benzyltetrahydroisoquinolines significantly. Not surprisingly, these ten alkaloids did not show noteworthy effects on TPC2 cation channels and the tumor cell line VCR-R CEM, and did not exhibit P-glycoprotein blocking activity. But due to their free phenolic groups they can serve as valuable intermediates for novel derivatives addressing all of these targets, based on previous evidence for structure–activity relationships in this chemotype.

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Section: Resultsmentioning

confidence: 99%

The ethoxycarbonyl group as both activating and protective group in N-acyl-Pictet–Spengler reactions using methoxystyrenes. A short approach to racemic 1-benzyltetrahydroisoquinoline alkaloids

Keller

Sauvageot-Witzku

Geisslinger

et al. 2021

Beilstein J. Org. Chem.

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Alkaloide aus Rhamnaceen, XXII. Amphibin‐I, ein neues Alkaloid aus Ziziphus amphibia A. Cheval.

1974

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Aus dem Rohbasengemisch von Ziziphus amphibia A. Cheval., in dem bisher nur Cyclopeptidalkaloide gefunden wurden 2-4). konnte das Aporphinalkaloid (-)-Nuciferins) (1) und Amphibin-I (2) isoliert werden. 2 hat die Struktur eines 6,7-Dimethoxy-2-methyl-l,2,3,4tetrahydroisochinolins mit einer Peptidseitenkette an C-I, wie durch chemischen Abbau und spektroskopische Methoden bewiesen werden konnte. Alkaloids from Rhamnaceae, Xxn 1) Amphibme-I, a new Alkaloid from Ziziphus amphibia A. Cheval.Amphibine-I (2) and the aporphine alkaloid (-)-Nuciferines) (1) have been isolated from the crude alkaloid extract of Ziziphus amphibia A. Cheval., in which previously only cyclopeptide alkaloids had been found 2-4). The structure of 2 was elucidated by spectroscopic and degradative methods as 6,7-dimethoxy-2-methyl-I ,2,3,4-tetrahydroisoquinoline with a peptide side chain at C-I.

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ChemInform Abstract: ISOLIERUNG VON (R)‐(‐)‐ARMEPAVIN AUS RHAMNUS FRANGULA L.

Pailer¹,

Haslinger²

1973

Chemischer Informationsdienst

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Isolierung von (R)-(?)-Armepavin aus Rhamnus frangula L

Cited by 6 publications

References 16 publications

The ethoxycarbonyl group as both activating and protective group in N-acyl-Pictet–Spengler reactions using methoxystyrenes. A short approach to racemic 1-benzyltetrahydroisoquinoline alkaloids

The ethoxycarbonyl group as both activating and protective group in N-acyl-Pictet–Spengler reactions using methoxystyrenes. A short approach to racemic 1-benzyltetrahydroisoquinoline alkaloids

Alkaloide aus Rhamnaceen, XXII. Amphibin‐I, ein neues Alkaloid aus Ziziphus amphibia A. Cheval.

ChemInform Abstract: ISOLIERUNG VON (R)‐(‐)‐ARMEPAVIN AUS RHAMNUS FRANGULA L.

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