Revision of the Structure of Escholidine

Chudík, Stanislav; Marek, Radek; Sečkářová, Pavlı́na; Nečas, Marek; Dostál, Jiřı́; Slavík, Jiří

doi:10.1021/np060078e

Cited by 12 publications

(7 citation statements)

References 19 publications

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“…S1 in Supporting Information) show the out-of-plane orientation of the methoxy groups in position 7 characterized by somewhat deshielded 13 C NMR resonance of the methyl carbon (δ~61 ppm, see Table 2). This deshielding for out-of-plane conformation was reported several times [25][26][27][28] and has been rationalized very recently by the paramagnetic deshielding effect of BD C-H → BD* (2) transition. [29] The NMR chemical shift of C8 was found in the range typical for the methoxy groups bonded to the aromatic system (δ~56 ppm, see Table 2).…”

Section: Results and Discussion Preparation And Characterizationsupporting

confidence: 59%

Structure and NMR properties of 6‐substituted‐5,6‐dihydrobenzo[c]phenanthridine alkaloids

Kadam

Maier

Šolomek

et al. 2013

J of Physical Organic Chem

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We report a preparation of new 6-substituted-5,6-dihydrobenzo[c]phenanthridines by the reaction of azoles with quaternary benzo[c]phenanthridine alkaloids sanguinarine and chelerythrine. The prepared compounds have been characterized by NMR spectroscopy, mass spectrometry, and single-crystal X-ray diffraction. Conformational behaviors of carbazole derivatives in solution have been investigated by low-temperature NMR experiments. Barriers to rotation around newly formed C6-N bonds were determined to be 12-13 kcal/mol. Quantum chemical calculations have been used to reproduce the experimental observations. Large structural effects on several 1 H NMR resonances were observed experimentally, analyzed by Density Functional Theory (DFT) calculations at B3LYP/6-311+G(d,p)/PCM level, and interpreted by ring-current effects of the benzo[c]phenanthridine and carbazole units.

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Section: Results and Discussion Preparation And Characterizationsupporting

confidence: 59%

Structure and NMR properties of 6‐substituted‐5,6‐dihydrobenzo[c]phenanthridine alkaloids

Kadam

Maier

Šolomek

et al. 2013

J of Physical Organic Chem

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“…Interestingly, a novel glycosylated protoberberine alkaloid putatively identified as escholidine‐9‐ O ‐glucoside was detected. This compound is potentially derived from nandinine (tetrahydroberberrubine) via escholidine ( N ‐methylnandinine; Chudik et al. , 2006) after methylenedioxy bridge formation in scoulerine (Ikezawa et al.…”

Section: Resultsmentioning

confidence: 99%

Targeted metabolite and transcript profiling for elucidating enzyme function: isolation of novel N‐methyltransferases from three benzylisoquinoline alkaloid‐producing species

et al. 2009

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SUMMARYAn integrated approach using targeted metabolite profiles and modest EST libraries each containing approximately 3500 unigenes was developed in order to discover and functionally characterize novel genes involved in plant-specialized metabolism. EST databases have been established for benzylisoquinoline alkaloid-producing cell cultures of Eschscholzia californica, Papaver bracteatum and Thalictrum flavum, and are a rich repository of alkaloid biosynthetic genes. ESI-FTICR-MS and ESI-MS/MS analyses facilitated unambiguous identification and relative quantification of the alkaloids in each system. Manual integration of known and candidate biosynthetic genes in each EST library with benzylisoquinoline alkaloid biosynthetic networks assembled from empirical metabolite profiles allowed identification and functional characterization of four N-methyltransferases (NMTs). One cDNA from T. flavum encoded pavine N-methyltransferase (TfPavNMT), which showed a unique preference for (AE)-pavine and represents the first isolated enzyme involved in the pavine alkaloid branch pathway. Correlation of the occurrence of specific alkaloids, the complement of ESTs encoding known benzylisoquinoline alkaloid biosynthetic genes and the differential substrate range of characterized NMTs demonstrated the feasibility of bilaterally predicting enzyme function and species-dependent specialized metabolite profiles.

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“…Significant changes in the chemical shifts of H-8 and H-13 were observed, due to the transformation of the QPA into the 7,8-dihydroprotoberberine skeleton. The chemical shift of H-8 in a 2,3,9,10-substituted QPA is found in the approximate range between 9.45 and 9.95 ppm [1,27] ; for all products a-d δ H8 = 6.3-7.2 ppm. An analogous tendency was observed for the 1 H NMR chemical shift of H-13.…”

Section: Resultsmentioning

confidence: 91%

Covalent bonding of azoles to quaternary protoberberine alkaloids

Grycová

Hulová

Maier

et al. 2008

Magnetic Reson in Chemistry

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Adducts of the quaternary protoberberine alkaloids (QPA) berberine, palmatine, and coptisine were prepared with nucleophiles derived from pyrrole, pyrazole, imidazole, and 1,2,4-triazole. The products, 8-substituted 7,8-dihydroprotoberberines, were identified by mass spectrometry and 1D and 2D NMR spectroscopy, including (1)H--(15)N shift correlations at natural abundance. In addition, two adducts of QPA with chloroform and methanethiolate were characterized by using NMR data. Single-crystal X-ray structures of 8-pyrrolyl-7,8-dihydroberberine, 8-pyrazolyl-7,8-dihydroberberine, and 8-imidazolyl-7,8-dihydroberberine are also presented.

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Revision of the Structure of Escholidine

Cited by 12 publications

References 19 publications

Structure and NMR properties of 6‐substituted‐5,6‐dihydrobenzo[c]phenanthridine alkaloids

Structure and NMR properties of 6‐substituted‐5,6‐dihydrobenzo[c]phenanthridine alkaloids

Targeted metabolite and transcript profiling for elucidating enzyme function: isolation of novel N‐methyltransferases from three benzylisoquinoline alkaloid‐producing species

Covalent bonding of azoles to quaternary protoberberine alkaloids

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