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1.
Forensic Sci Int ; 269: 31-41, 2016 Dec.
Article in English | MEDLINE | ID: mdl-27863282

ABSTRACT

In February 2016, nine "spice-like" products from German language internet shops were analyzed. In total, eight different synthetic cannabinoids were identified by gas chromatography-mass spectrometry (GC-MS), namely THJ-018, THJ-2201, MAB-CHMINACA, 5F-ADB, 5Cl-AKB48 (syn.: 5C-AKB48), 4-pentenyl-AKB48, MDMB-CHMICA and 5F-AB-PINACA. For the majority of products only one synthetic cannabinoid was identified as the active ingredient, while two products contained 2 and 5 compounds, respectively. For some of the identified cannabinoids (MAB-CHMINACA, 5Cl-AKB48 and 4-pentenyl-AKB48) no or only insufficient physico-chemical data were available in literature. To our knowledge 5Cl-AKB48 and 4-pentenyl-AKB48 were found for the first time in commercially available products, hence an in-depth characterization of these compounds by NMR, EI-MS, ESI-MS/MS, IR- and UV spectroscopy was conducted. In addition, all synthetic cannabinoids were quantified by a GC-MS method using JWH-018 as internal standard and the corresponding response factors to calculate the total amount of all synthetic cannabinoids in the commercial smoking mixtures. The content of synthetic cannabinoids in the investigated products ranged from 23 to 120mg/g (average: 57mg/g), while individual compounds ranged from 1 to 120mg/g.


Subject(s)
Cannabinoids/chemistry , Designer Drugs/chemistry , Illicit Drugs/chemistry , Gas Chromatography-Mass Spectrometry , Humans , Magnetic Resonance Spectroscopy , Molecular Structure
2.
Phytochemistry ; 116: 269-282, 2015 Aug.
Article in English | MEDLINE | ID: mdl-25823584

ABSTRACT

Equisetum palustre L. is known for its toxicity for livestock. Several studies in the past addressed the isolation and identification of the responsible alkaloids. So far, palustrine (1) and N(5)-formylpalustrine (2) are known alkaloids of E. palustre. A HPLC-ESI-MS/MS method in combination with simple sample work-up was developed to identify and quantitate Equisetum alkaloids. Besides the two known alkaloids six related alkaloids were detected in different Equisetum samples. The structure of the alkaloid palustridiene (3) was derived by comprehensive 1D and 2D NMR experiments. N(5)-Acetylpalustrine (4) was also thoroughly characterized by NMR for the first time. The structure of N(5)-formylpalustridiene (5) is proposed based on mass spectrometry results. Twenty-two E. palustre samples were screened by a HPLC-ESI-MS/MS method after development of a simple sample work-up and in most cases the set of all eight alkaloids were detected in all parts of the plant. A high variability of the alkaloid content and distribution was found depending on plant organ, plant origin and season ranging from 88 to 597mg/kg dried weight. However, palustrine (1) and the alkaloid palustridiene (3) always represented the main alkaloids. For the first time, a comprehensive identification, quantitation and distribution of Equisetum alkaloids was achieved.


Subject(s)
Alkaloids/isolation & purification , Equisetum/chemistry , Alkaloids/analysis , Alkaloids/chemistry , Chromatography, High Pressure Liquid , Electron Spin Resonance Spectroscopy , Molecular Structure , Nuclear Magnetic Resonance, Biomolecular
3.
J Mass Spectrom ; 50(8): 978-986, 2015 Aug.
Article in English | MEDLINE | ID: mdl-28338276

ABSTRACT

The fragment spectra of protonated nitro-substituted benzodiazepines show an unusual fragment [M + H - 14]+ , which is shown by accurate mass measurement to be due to the loss of a nitrogen atom. Our investigations show that this apparent loss of atomic nitrogen is rather an attachment of molecular oxygen to the [M + H - NO2 ]+• ion, which is the main fragment ion in these spectra. The oxygen attachment is exothermic, and rate constants have been derived. MSn spectra show that it is not easily reversible upon fragmentation of the adduct ion and that it is also observed with some secondary and tertiary fragments, which allows to limit the attachment site to the aromatic ring annulated to the diazepine moiety. Fragments of the oxygen adduct ion indicate that the O2 molecule dissociates in the adduct formation process, and the two oxygen atoms are bound to different sites of the ion. Comparison with radical cations generated by fragmentation of non-nitro-substituted benzodiazepines, none of which showed an oxygen attachment, and the fragmentation mechanisms involved in their formation indicates that the [M + H - NO2 ]+• ion is a distonic ion with the charge and radical site neighbored on the aromatic ring. From these results, we derive a proposal for the formation and structure of the [M + H - NO2 + O2 ]+• ion, which explains the experimental observations. Copyright © 2015 John Wiley & Sons, Ltd.

4.
Drug Test Anal ; 6(1-2): 59-71, 2014.
Article in English | MEDLINE | ID: mdl-23723183

ABSTRACT

Synthetic compounds mimicking cannabis-like effects are a recent trend. Currently, these so-called synthetic cannabinoids are the largest and fastest growing class of newly appearing designer drugs. Many national authorities are continuously adapting their regulations to keep pace with the permanently changing variety of compounds. We have analyzed eight herbal smoking blends containing synthetic cannabinoids. Altogether, nine compounds could be identified, namely AM-2201, AM-2201-pMe (MAM-2201), AM-1220, AM-1220-azepane, UR-144, XLR-11, JWH-122-pentenyl, AM-2232, and STS-135. Newly appearing compounds were isolated by column chromatography and their structures elucidated by 1D- and 2D-nuclear magnetic resonance (NMR) experiments. In addition, the compounds were investigated by electron ionization-mass spectrometry (EI-MS) and electrospray ionization-tandem mass spectrometry (ESI-MS/MS) to complete the physicochemical dataset. Based on the purified compounds a universal gas chromatography-mass spectrometry (GC-MS) method was developed for the identification and quantification of these compounds in commercial smoking blends. By applying this method, up to five different compounds could be found in such products showing total concentrations from 72 to 303 mg/g smoking blend while individual compounds ranged from 0.4 to 303 mg/g. (1)H NMR spectra of the chiral compounds AM-1220 and its azepane-isomer recorded in the presence of 1 equivalent of (R)-(+)-α-methoxy-α-trifluoromethylphenylacetic acid (MTPA, Mosher's acid) showed them to be racemic mixtures.


Subject(s)
Adamantane/analogs & derivatives , Cannabinoids/analysis , Designer Drugs/analysis , Indoles/analysis , Adamantane/analysis , Gas Chromatography-Mass Spectrometry , Magnetic Resonance Spectroscopy , Spectrometry, Mass, Electrospray Ionization , Tandem Mass Spectrometry
5.
J Agric Food Chem ; 61(47): 11382-91, 2013 Nov 27.
Article in English | MEDLINE | ID: mdl-24245544

ABSTRACT

Contamination of food and feed with pyrrolizidine alkaloids is currently discussed as a potential health risk. Here, we report the development of a new HPLC-ESI-MS/MS sum parameter method to quantitate the pyrrolizidine alkaloid content in complex food matrices. The procedure was validated for honey and culinary herbs. Isotopically labeled 7-O-9-O-dibutyroyl-[9,9-(2)H2]-retronecine was synthesized and utilized as an internal standard for validation and quantitation. The total pyrrolizidine alkaloid content of a sample is expressed as a single sum parameter: retronecine equivalents (RE). Ld/Lq for honey was 0.1 µg RE/kg/0.3 µg RE/kg. For culinary herbs, 1.0 µg RE/kg/3.0 µg RE/kg (dry weight, dw) and 0.1 µg RE/kg/0.3 µg RE/kg (fresh weight, fw) were determined, respectively. The new method was applied to analyze 21 herbal convenience products. Fifteen products (71%) were pyrrolizidine alkaloid positive showing pyrrolizidine alkaloid concentrations ranging from 0.9 to 74 µg RE/kg fw.


Subject(s)
Chromatography, High Pressure Liquid/methods , Food Analysis/methods , Food Contamination/analysis , Pyrrolizidine Alkaloids/analysis , Spectrometry, Mass, Electrospray Ionization/methods , Tandem Mass Spectrometry/methods , Borago/chemistry , Honey , Limit of Detection , Pyrrolizidine Alkaloids/chemistry , Reproducibility of Results
6.
Forensic Sci Int ; 222(1-3): 216-22, 2012 Oct 10.
Article in English | MEDLINE | ID: mdl-22748479

ABSTRACT

Herbal smoking blends, available on the German market were analyzed and several known synthetic cannabinoids were identified (JWH-122 and JWH-018). In addition, we isolated a new active ingredient by silica gel column chromatography and elucidated the structure by nuclear magnetic resonance (NMR) methods. The compound was identified as JWH-307, a synthetic cannabinoid of the phenyl-pyrrole subclass with known in vitro binding affinities for cannabinoid receptors. To date, this is the first appearance of this subclass of cannabimimetics in such products. JWH-307 has been further characterized by gas chromatography accurate mass spectrometry (GC-HRMS), electrospray tandem mass spectrometry (ESI-MS/MS), ultraviolet (UV) and infrared (IR) spectroscopy. JWH-018 was among the first compounds banned by many countries world-wide including Germany. The identification of JWH-018 was striking, since this is the first report where JWH-018 recurred on the German market thus violating existing laws. A generic method was established to quantify synthetic cannabinoids in herbal smoking blends. Quantification was achieved using an isotopically labeled standard (JWH-018-D(3)). JWH-018 was found at a level of 150 mg/g while JWH-122 and JWH-307 occurred as a mixture at a total level of 232 mg/g.

7.
Anal Bioanal Chem ; 404(1): 157-71, 2012 Jul.
Article in English | MEDLINE | ID: mdl-22710567

ABSTRACT

In this study, seven commercial "spice-like" products available on the German market were analyzed. They all contained significant amounts of synthetic cannabinoids and had distinctly different compositions of these adulterants. All synthetic cannabinoids were extracted and purified by different chromatographic techniques from the respective product. The structures of all compounds were elucidated by nuclear magnetic resonance spectroscopy and further characterized by mass spectrometry (MS) and ultraviolet and infrared spectroscopy to generate a full data set of each compound. Altogether, eight compounds were identified, and one deuterium-labeled cannabinoid was used as internal standard. Four products contained only one individual compound, while three products contained mixtures of two compounds. Among the eight isolated compounds, six were already known from recent publications (JWH-081, JWH-210, JWH-122, AM2201, RCS-4, and JWH-203), but the published data were not always complete. In addition, two unknown compounds (AM2201-pMe, RCS-4-(N-Me)) were isolated. Overall, compounds from three distinct classes of synthetic cannabinoids could be identified, characterized, and compared. The MS data of the different subclasses allowed the postulation of some general key fragmentations to distinguish between these subclasses. In addition, we established a general method using an isotopically labeled internal standard (JWH-018-D(3)) to quantify synthetic cannabinoids in herbal mixtures. The total content of the synthetic cannabinoids ranged from 77.5 to 202 mg/g, while individual compounds were detected from 19.3 to 202 mg/g in these products. The spectroscopic data for all compounds mentioned here were collected and added en bloc as Electronic supplementary material to this manuscript.


Subject(s)
Cannabinoids/chemistry , Illicit Drugs/chemistry , Indoles/chemistry , Magnetic Resonance Spectroscopy/methods , Mass Spectrometry/methods , Plant Preparations/chemistry , Cannabinoids/chemical synthesis , Cannabinoids/economics , Germany , Illicit Drugs/chemical synthesis , Illicit Drugs/economics , Indoles/chemical synthesis , Indoles/economics , Molecular Structure
8.
J Mass Spectrom ; 46(7): 615-24, 2011 Jul.
Article in English | MEDLINE | ID: mdl-21671437

ABSTRACT

SAR-943 (32-deoxo rapamycin) is a proliferation signal inhibitor via interaction with the mammalian target of rapamycin (mTOR). Most importantly, SAR-943 has improved chemical stability compared to rapamycin (sirolimus) and is currently under investigation as a drug coated on coronary stents. It was the goal of this study to identify the SAR-943 metabolites generated after incubation with human liver microsomes using high-resolution mass spectrometry (MS) and MS/iontrap (MS(n)) and comparison of fragmentation patterns of the metabolites with those of SAR-943 and other known rapamycin derivatives. Our study showed that SAR-943 is mainly hydroxylated and/or demethylated by human liver microsomes. The structures of the following metabolites were identified: O-demethylated metabolites: 39-O-desmethyl, 16-O-desmethyl and 27-O-desmethyl SAR-943; hydroxylated metabolites: hydroxy piperidine SAR-943, 11-hydroxy, 12-hydroxy, 14-hydroxy, 23-hydroxy, 24-hydroxy, 25-hydroxy, 46-hydroxy and 49-hydroxy SAR-943; didemethylated metabolites: 16,39-O-didesmethyl and 27,39-O-didesmethyl SAR-943; demethylated-hydroxylated metabolites: 39-O-desmethyl, 23- or 24-hydroxy and 39-O-desmethyl, hydroxy piperidine SAR-943 and dihydroxylated metabolites: 12-,23- or 24-dihydroxy SAR-943. In addition, several other demethylated-hydroxylated and dihydroxylated metabolites were detected. However, their exact structures could not be identified.


Subject(s)
Mass Spectrometry/methods , Microsomes, Liver/metabolism , Sirolimus/analogs & derivatives , Drug Stability , Drug-Eluting Stents , Humans , Hydroxylation , Methylation , Microsomes, Liver/chemistry , Sirolimus/analysis , Sirolimus/chemistry , Sirolimus/metabolism
9.
Forensic Sci Int ; 208(1-3): e31-5, 2011 May 20.
Article in English | MEDLINE | ID: mdl-21482054

ABSTRACT

Recently, several cases across Germany were reported where teenagers were hospitalized showing severe side effects after consumption of a new "Spice-like" herbal incense called "Lava red". The active component of "Lava red", obtained from German internet shops, was isolated by silica gel column chromatography and the structure was elucidated by NMR methods. It is a known N-alkyl-3-(1-naphthoyl)indole (CAS No.: 619294-47-2) JWH-122 which was synthesized recently as model component for in vitro drug testing. The structure is related to compounds that were used two years ago (JWH-018, JWH-073) as synthetic cannabimimetics in similar incense products which are now banned as illegal drugs in Germany and several other European countries. The concentration of JWH-122 was estimated to be 82mg/g product. The isolated compound was further analyzed by different spectroscopic and mass spectrometry techniques to obtain a complete dataset of the physico-chemical properties of the molecule. The data presented here is useful for easy and fast detection of JWH-122 in trace amounts in complex matrices.

10.
Forsch Komplementmed ; 17(1): 15-20, 2010 Mar.
Article in English | MEDLINE | ID: mdl-20215758

ABSTRACT

INTRODUCTION: Aqueous and ethanolic extracts of Cajanus cajan (Fabaceae) were examined in vitro for their antiviral activity against herpes simplex virus type 1 (HSV-1) and type 2 (HSV-2). MATERIALS AND METHODS: The antiviral activity was determined using a plaque reduction assay. The cytotoxic concentration (CC50) as well as the inhibitory concentration (IC50) of the extracts was determined from dose-response curves. RESULTS: All extracts tested revealed a high antiviral activity against cell-free HSV-1 and HSV-2. The most active one was the Cajanus ethanol extract with IC50 values of 0.022 microg/ml for HSV-1 and 0.1 microg/ml for HSV-2. In order to identify the mode of antiviral action, the extracts were added to the host cells or viruses at different stages of infection. HSV-1 and HSV-2 were considerably inactivated when the viruses were pretreated with the extracts for 1 h prior to cell infection. At maximum non-cytotoxic concentrations of the extracts, plaque formation was significantly reduced by 95-99% for HSV-1 and HSV-2. In a time-dependent assay with cell-free HSV-1 over a period of 2 h, a clearly time-dependent effect was demonstrated whereby the Cajanus ethanol extract revealed a much higher activity than the Cajanus aqueous one. CONCLUSION: The results obtained indicate that the extracts affect HSV before cell adsorption, but have no effect on the intracellular virus replication. According to our findings, a therapeutic application of Cajanus ethanolic extracts containing crème or ointment as antiviral agent in recurrent HSV infection appears to be promising.


Subject(s)
Antiviral Agents/pharmacology , Cajanus/chemistry , Ethanol/chemistry , Herpesvirus 1, Human/drug effects , Herpesvirus 2, Human/drug effects , Plant Extracts/pharmacology , Water/chemistry , Animals , Cell Line , Cell Survival/drug effects , Chlorocebus aethiops , Herpes Simplex/drug therapy , Inhibitory Concentration 50 , Plant Extracts/toxicity , Time Factors
11.
Biol Chem ; 391(1): 55-63, 2010 Jan.
Article in English | MEDLINE | ID: mdl-19919179

ABSTRACT

During heme biosynthesis the oxygen-independent coproporphyrinogen III oxidase HemN catalyzes the oxidative decarboxylation of the two propionate side chains on rings A and B of coproporphyrinogen III to the corresponding vinyl groups to yield protoporphyrinogen IX. Here, the sequence of the two decarboxylation steps during HemN catalysis was investigated. A reaction intermediate of HemN activity was isolated by HPLC analysis and identified as monovinyltripropionic acid porphyrin by mass spectrometry. This monovinylic reaction intermediate exhibited identical chromatographic behavior during HPLC analysis as harderoporphyrin (3-vinyl-8,13,17-tripropionic acid-2,7,12,18-tetramethylporphyrin). Furthermore, HemN was able to utilize chemically synthesized harderoporphyrinogen as substrate and converted it to protoporphyrinogen IX. These results suggest that during HemN catalysis the propionate side chain of ring A of coproporphyrinogen III is decarboxylated prior to that of ring B.


Subject(s)
Coproporphyrinogen Oxidase/metabolism , Coproporphyrinogens/metabolism , Porphyrinogens/metabolism , Protoporphyrins/biosynthesis , Chromatography, High Pressure Liquid , Humans , Nuclear Magnetic Resonance, Biomolecular
12.
FEBS J ; 276(20): 5973-82, 2009 Oct.
Article in English | MEDLINE | ID: mdl-19754882

ABSTRACT

Biosynthesis of heme d(1), the essential prosthetic group of the dissimilatory nitrite reductase cytochrome cd(1), requires the methylation of the tetrapyrrole precursor uroporphyrinogen III at positions C-2 and C-7. We produced Pseudomonas aeruginosa NirE, a putative S-adenosyl-L-methionine (SAM)-dependent uroporphyrinogen III methyltransferase, as a recombinant protein in Escherichia coli and purified it to apparent homogeneity by metal chelate and gel filtration chromatography. Analytical gel filtration of purified NirE indicated that the recombinant protein is a homodimer. NirE was shown to be a SAM-dependent uroporphyrinogen III methyltransferase that catalyzes the conversion of uroporphyrinogen III into precorrin-2 in vivo and in vitro. A specific activity of 316.8 nmol of precorrin-2 h(-1) x mg(-1) of NirE was found for the conversion of uroporphyrinogen III to precorrin-2. At high enzyme concentrations NirE catalyzed an overmethylation of uroporphyrinogen III, resulting in the formation of trimethylpyrrocorphin. Substrate inhibition was observed at uroporphyrinogen III concentrations above 17 microM. The protein did bind SAM, although not with the same avidity as reported for other SAM-dependent uroporphyrinogen III methyltransferases involved in siroheme and cobalamin biosynthesis. A P. aeruginosa nirE transposon mutant was not complemented by native cobA encoding the SAM-dependent uroporphyrinogen III methyltransferase involved in cobalamin formation. However, bacterial growth of the nirE mutant was observed when cobA was constitutively expressed by a complementing plasmid, underscoring the special requirement of NirE for heme d(1) biosynthesis.


Subject(s)
Bacterial Proteins/metabolism , Heme/analogs & derivatives , Methyltransferases/chemistry , Methyltransferases/metabolism , Pseudomonas aeruginosa/enzymology , Pseudomonas aeruginosa/genetics , Amino Acid Sequence , Bacterial Proteins/chemistry , Bacterial Proteins/genetics , Genetic Complementation Test , Heme/biosynthesis , Methyltransferases/genetics , Molecular Sequence Data , Protein Binding , Pseudomonas aeruginosa/growth & development , Pseudomonas aeruginosa/metabolism , S-Adenosylmethionine/metabolism , Sequence Homology, Amino Acid , Substrate Specificity , Uroporphyrinogens/metabolism , Uroporphyrins/metabolism
13.
J Mass Spectrom ; 42(8): 1024-44, 2007 Aug.
Article in English | MEDLINE | ID: mdl-17605143

ABSTRACT

The collision-induced dissociations of the even-electron [M + H](+) and/or [M - H](-) ions of 121 model compounds (mainly small aromatic compounds with one to three functional groups) ionized by electrospray ionization (ESI) or atmospheric pressure chemical ionization (APCI) have been studied using an ion trap instrument, and the results are compared with the literature data. While some functional groups (such as COOH, COOCH(3), SO(3)H in the negative ion mode, or NO(2) in both the positive and negative ion modes) generally promote the loss of neutrals that are characteristic as well as specific, other functional groups (such as COOH in the positive ion mode) give rise to the loss of neutrals that are characteristic, but not specific. Finally, functional groups such as OH and NH(2) in aromatic compounds do not lead to the loss of a neutral that reflects the presence of these substituents. In general, the dissociation of [M + H](+) and [M - H](-) ions generated from aliphatic compounds or compounds containing an aliphatic moiety obeys the even-electron rule (loss of a molecule), but deviations from this rule (loss of a radical) are sometimes observed for aromatic compounds, in particular for nitroaromatic compounds. Thermochemical data and ab initio calculations at the CBS-QB3 level of theory provide an explanation for these exceptions. When comparing the dissociation behaviour of the even-electron [M + H](+) and/or [M - H](-) ions (generated by ESI or APCI) with that of the corresponding odd-electron [M](+) ions (generated by electron ionization, EI), three cases may be distinguished: (1) the dissociation of the two ionic species differs completely; (2) the dissociation involves the loss of a common neutral, yielding product ions differing in mass by one Da, or (3) the dissociations lead to a common product ion.


Subject(s)
Electrons , Organic Chemicals/chemistry , Spectrometry, Mass, Electrospray Ionization/methods , Atmospheric Pressure , Ions , Organic Chemicals/analysis
14.
J Mass Spectrom ; 42(6): 793-802, 2007 Jun.
Article in English | MEDLINE | ID: mdl-17511017

ABSTRACT

Everolimus (40-O-(2-hydroxyethyl)rapamycin, Certican) is a 31-membered macrolide lactone. In lymphocytes, it inhibits the mammalian target of rapamycin (mTOR) and is used as an immunosuppressant after organ transplantation. Due to its instability in pure organic solvents and insufficient HPLC separation, NMR spectroscopy analysis of its metabolite structures is nearly impossible. Therefore, structural identification based on tandem mass spectrometry (MS/MS) and MS(n) fragmentation patterns is critical. Here, we have systematically assessed the fragmentation pattern of everolimus during liquid chromatography (LC)-electrospray ionization (ESI)-MS/MS and validated the fragment structures by (1) comparison with structurally identified derivatives (sirolimus), (2) high-resolution mass spectrometry, (3) elucidation of fragmentation pathways using ion trap mass spectrometry (up to MS(5)) and (4) H/D exchange. In comparison with the structurally related immunosuppressants tacrolimus and sirolimus, our study was complicated by the low ionization efficiency of everolimus. Detection of positive ions gave the best sensitivity, and everolimus and its fragments were mainly detected as sodium adducts. LC-ESI-MS/MS of everolimus in combination with collision-induced dissociation (CID) resulted in a complex fragmentation pattern and the structures of 53 fragments were identified. These detailed fragmentation pathways of everolimus provided the basis for structural elucidation of all everolimus metabolites generated in vivo und in vitro.


Subject(s)
Immunosuppressive Agents/chemistry , Sirolimus/analogs & derivatives , Spectrometry, Mass, Electrospray Ionization/methods , Tandem Mass Spectrometry/methods , Chromatography, High Pressure Liquid , Everolimus , Molecular Structure , Sirolimus/chemistry
15.
J Chromatogr A ; 1067(1-2): 55-72, 2005 Mar 04.
Article in English | MEDLINE | ID: mdl-15844510

ABSTRACT

The present paper provides a summary of the collision-induced dissociation of protonated and deprotonated phase II metabolites of drugs and pesticides. This overview is based on published literature and unpublished data from the authors. In particular, glutathione conjugates and their biotransformation products are discussed in detail. In addition, the fragmentation of the major classes of conjugates, i.e. glucuronides, glucosides, malonylglucosides, sulfates, acetates, methyl and glycine conjugates, is reported. Collision-induced dissociation, as studied by tandem mass spectrometry, allows the rapid identification of the type of conjugate, whereas the exact conjugation site can in general be determined only by additional NMR experiments.


Subject(s)
Mass Spectrometry/methods , Pesticides/metabolism , Pharmaceutical Preparations/metabolism
17.
Angew Chem Int Ed Engl ; 40(13): 2471-2474, 2001 Jul 02.
Article in English | MEDLINE | ID: mdl-29712273

ABSTRACT

Surprisingly selective is the preparation of the novel 1,3,4-triphosphole complex 1 by insertion of a phosphaalkyne into a 1H-diphosphirene complex. NMR spectroscopic experiments and quantum-mechanical calculations indicate a small P-inversion barrier for the σ3 -phosphorus center in 1 as well as new possibilities of "π-tuning".

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