Pathway isoquinoline

Pathway Isoquinoline alkaloid biosynthesis (m00950), metabolic pathways (mOl 100),... 

Roger P, G Bar, E Lingens (1995) Two novel metabolites in the degradation pathway of isoquinoline by Pseudomonas diminuta 1. FEMS Microbiol Lett 129 281-286. 

Figure 24. Hypothetical pathway of aerobic degradation of isoquinoline (Compound in brackets not detected).

Roger, P. Bar, G. and Lingens, F., Novel Metabolites in the Degradation Pathway of Isoquinoline by Pseudomonas-Diminuta-7. FEMS Microbiol Lett, 1995. 129(2-3) pp. 281-285. 

Regiospecific ring expansion has been observed on irradiation of the 3-substituted 1-iminopyridinium ylids 92 to give the l//-l,2-diazepines 93.78 Various novel ring systems have been prepared in an analogous fashion. Thus, for example, the previously unknown 1H-1,3-benzodiazepines 94 were obtained by irradiation in dichloromethane of the isoquinoline /V-imides 9579 a possible pathway is outlined in Scheme 2. The novel ring systems, If/-1,3- and 3//-2,3-thieno[2,3-d]diazepines, have similarly been prepared by irradiation of 7-methylthieno[2,3-c]pyridine /V-imides,80 and... 

One of the first demonstrations of the central monoamine pathways in the mammalian brain was by a fluorescence technique in which thin sections of the animal brain were exposed to formaldehyde vapour which converted the amines to their corresponding fluorescent isoquinolines. The distribution of these compounds could then be visualized under the fluorescent microscope. Using this technique it has been possible to map the distribution of the noradrenergic, dopaminergic and serotonergic pathways in the animal and human brain. 

Unexpected oxazoline formation was observed during a study to prepare nonsedating anxiolytic 1-styrylisoquinolines 27a-h from 2-(trifluoromethyl)aryl-ethylamines 25a-h under Pictet-Gams conditions (POCI3 in refluxing toluene). This deviation from the normal reaction pathway was hypothesized to result from the electron-withdrawing effect of trifluoromethyl group that inhibited the formation of a benzylic cation required for isoquinoline formation (Scheme 8.12). 

The Pictet-Spengler and Bischler-Napieralski reactions are used to prepare biologically and pharmocologically important isoquinoline ring systems. Versions of these reactions have also been proposed in biosynthetic pathways. Under mildly to strongly acidic conditions, the cyclizations... 

Abstract The multi-step enzyme catalysed biosyntheses of monoterpenoid indole and isoquinoline alkaloids are described. Special emphasis is placed on those pathways leading to alkaloids of pharmacological and medicinal significance which have been fully elucidated at the enzyme level. The successful identification and cloning of cDNAs of single enzymes and their application provides great opportunities to develop novel strategies for both in vitro and in vivo alkaloid production in whole plants or tissue cultures, as well as in microbial systems such as Escherichia coli and yeast. 

Fig. 18 Reconstructed isoquinoline alkaloid biosynthetic pathway in microbes (E. coli and S. cerevisiae) [120]. Accession numbers of the genes can be taken from Gene Bank. C3,4-DHPA-A 3,4-dihydroxyphenylacetaldehyde NCS norcoclaurine synthase 60MT 6-0-methyltransferase CNMT coclaurine-/V-mcthyltransferase 4 OMT 4 -0-methyltransferase BBE berberine bridge enzyme NMT /V-methyltransferase)...

A wide range of substituted isoquinolines (93) have been synthesized via a highly efficient nickel-catalysed annulation of the r-butylimines of 2-iodobenzaldehydes (91) and various alkynes (92) examination of the regiochemistry of the reaction revealed the operation of two different alkyne insertion pathways.119... 

It has been reported119 that when 2-methyl-1,2,3,4-tetrahydro-isoquinoline-3-carboxylate is heated to about 200° in the presence of benzaldehyde, 4-benzylisoquinoline is formed and can be isolated in 73% yield. It is probable that decarboxylation occurs to form 2-methyl-l,2,3,4-tetrahydroisoquinoline, which then reacts with benzaldehyde via the enamine pathway as before. 

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