Aromatization of 1‐Benzyltetrahydroisoquinolines: Racemization of (−)‐(<i>S</i>)‐(<i>N</i>‐nor)‐Reticuline

Buchs, Peter; Brossi, Arnold

doi:10.1002/hlca.19810640310

Cited by 11 publications

(4 citation statements)

References 11 publications

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“…The EI mass spectra of cis ‐(1) and trans ‐1,2‐cyclopentanediol ( 2 ) and cis ‐( 3 ) and trans ‐1,2‐cyclohexanediol ( 4 ) are identical for each pair of stereoisomers, and classical ions,10–12 such as M + , [M − H 2 O] +· and [M − H 2 O − C 2 H 4 ] +· , were obtained.…”

Section: Resultsmentioning

confidence: 99%

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Stereochemical differentiation of cyclic glycols by ion-molecule reactions in a quadrupole mass spectrometer using dimethyl ether acetonitrile and 2-S-pyrrolidinemethanol

Mancel

Sellier

2000

Rapid Commun. Mass Spectrom.

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In this study, ion-molecule reactions using chemical ionization in the positive ion mode using dimethyl ether, acetonitrile and 2-S-pyrrolidinemethanol as reagent gases have been used to distinguish between cis- and trans-1,2-cyclopentanediol and cis- and trans-1,2-cyclohexanediol. In the gas phase, the stereospecific ion-molecule reaction gives characteristic ions and substantial differences are observed in their relative abundances from which the diastereoisomers of those cyclic glycols can be clearly differentiated. Copyright 2000 John Wiley & Sons, Ltd.

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Section: Resultsmentioning

confidence: 99%

“…The similarity of the EI mass spectra of cyclic 1,2‐diols makes it almost impossible to differentiate the stereoisomers 10–12. In contrast, the differentiation of these isomers by PCI is possible.…”

mentioning

confidence: 99%

Stereochemical differentiation of cyclic glycols by ion-molecule reactions in a quadrupole mass spectrometer using dimethyl ether acetonitrile and 2-S-pyrrolidinemethanol

Mancel

Sellier

2000

Rapid Commun. Mass Spectrom.

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“…A number of protocols were investigated for the oxidation of the tetrahydroisoquinolines to their corresponding isoquinoline derivatives including those involving the use of IBX and sulfur . In our hands, the method described by Buchs and Brossi , involving dehydrogenation with Pd/C showed itself to be the most general and gave the best yields. For example, 1-(3,4-dimethoxyphenyl)-6,7-dimethoxy-1,2,3,4-tetrahydroisoquinoline ( 4a ) was dehydrogenated with Pd/C in toluene to give 98% of the corresponding isoquinoline ( 4b ).…”

Section: Resultsmentioning

confidence: 71%

Strategies and Synthetic Methods Directed Toward the Preparation of Libraries of Substituted Isoquinolines

Awuah

Capretta

2010

J. Org. Chem.

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Strategies for the production of substituted isoquinoline libraries were developed and explored. Routes involving microwave-assisted variants of the Bischler-Napieralski or Pictet-Spengler reaction allowed for cyclization of substituted beta-arylethylamine derivatives. The dihydroisoquinolines and tetrahydroisoquinolines thus generated could then be oxidized to their corresponding isoquinoline analogues. An alternate strategy, however, involving the preparation and activation of isoquinolin-1(2H)-ones is demonstrated to be a more practical, rapid, and efficient route to C1- and C4-substituted isoquinoline libraries.

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“…Benzoyl derivative 9 [29-331 was prepared from 5 by a published procedure [31] and converted by dehydrogenation over Pd/C in refluxing toluene [34] into isoquinoline 10. Imidazolinium chloride 11 (Scheme 2 ) , quantitatively obtained from 9 in 0 .…”

Section: Mammalian Alkaloidsmentioning

confidence: 99%

ChemInform Abstract: Mammalian Alkaloids: O‐Methylation of (S)‐ and (R)‐Dideoxynorlaudanosoline‐1‐carboxylic Acid by Catechol O‐Methyltransferase and Identification of a Yellow Pigment Obtained at Physiological pH.

et al. 1989

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0 -Methylation of optically active 3',4-dideoxynorlaudanosoline-l-carboxylic acids 1 with O-methyltransferase in vitro afforded almost exclusively the 7-0-methylated acids 3. A similar result was obtained with the yellow quinonemethide 4A obtained from 1 at neutral or slightly alkaline pH by oxidative decarboxylation and affording the 3,4-dihydroisoquinoline 15 on methylation with catechol 0-methyltransferase (COMT). The structure of quinonemethide 4A was determined on the basis of spectral data, by its conversion into isoquinolines of established structure, and by synthesis. Quinonemethide 4A was found to he a weak inhibitor of monoamine oxidase A (MA0 A) but not a substrate. Nonenzymatic oxidative decarboxylation of dopamine-derived tetrahydroisoquinoline-I-carhoxylic acids to quinonemethides may be a major factor in biochemical experimentation and should be considered in the interpretation of data.Introduction. -Mammalian alkaloids are formed in mammals under physiological conditions apparently by Pictet-Spengler cyclization of catecholamines (e.g. dopamine and norepinephrine) or indolethylamines (e.g. tryptamine and 5-hydroxytryptamine) with a-keto analogs of aromatic amino acids or aldehydes [l-81. There is substantial evidence that some 1,2,3,4-tetrahydroisoquinolines, 1,2,3,4-tetrahydroisoquinoline-1-carboxylic acids, and /3-carbolines, prepared by Hahn et al. more than 30 years ago [9] [lo], are present in small amounts in vivo and occur at increased levels in certain pathological conditions [ 111. Tetrahydroisoquinoline-1-carboxylic acid 1, which is found in higher concentrations in phenylketonurics than in healthy subjects [l 11, has been thought to contribute to the neurological changes manifested in this disease [12] [13]. Acid 1 was originally prepared by Hahn et al. as a racemic mixture [9], but its optical isomers have recently been obtained [ 141. Since optically active /3-carbolines have been reported to occur in mammalian tissues [ 151 [ 161 and optically active l-benzyl-tetrahydroisoquinolines were found to be highly potent in adrenergic and dopaminergic receptor binding assays [17], we chose to investigate the optical isomers of acid 1 to determine whether they would behave differently in biochemical assays and provide data which would ultimately clarify the origin of the mammalian material. Bobbitt [ 181 reported that 6-hydroxy-tetrahydroisoquinoline-1-carbroxylic acids spontaneously decarboxylate at pH 7 or above in ') Visiting scientist, Faculty of Chemistry, A. Mickiewicz University, Poznan, Poland.HELVETICA CHIMICA ACTA -Vol. 71 (1988) the presence of air to 3,4-dihydroisoquinolines. This finding suggests that the optically active tetrahydroisoquinoline-1-carboxylic acids are not converted into optically active tetrahydroisoquinolines primarily by enzymic decarboxylation.Enzymatic methylation of (f)-salsolinol-1-carboxylic acid (1 -methyl analog of 1) has been examined, and the 7-methyl ether analog was found as the exclusive 0-methyl metabolite [ 191. However, this high regiospe...

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Aromatization of 1‐Benzyltetrahydroisoquinolines: Racemization of (−)‐(S)‐(N‐nor)‐Reticuline

Cited by 11 publications

References 11 publications

Stereochemical differentiation of cyclic glycols by ion-molecule reactions in a quadrupole mass spectrometer using dimethyl ether acetonitrile and 2-S-pyrrolidinemethanol

Stereochemical differentiation of cyclic glycols by ion-molecule reactions in a quadrupole mass spectrometer using dimethyl ether acetonitrile and 2-S-pyrrolidinemethanol

Strategies and Synthetic Methods Directed Toward the Preparation of Libraries of Substituted Isoquinolines

ChemInform Abstract: Mammalian Alkaloids: O‐Methylation of (S)‐ and (R)‐Dideoxynorlaudanosoline‐1‐carboxylic Acid by Catechol O‐Methyltransferase and Identification of a Yellow Pigment Obtained at Physiological pH.

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