Reactivity of the 1
            <i>H</i>
            ‐Pyrrole Ring System

Jackson, Anthony H.; Artico, M.; Anderson, Hugh J.; Loader, C. E.; Gossauer, Albert; Nesvadba, Petr; Dennis, N.

doi:10.1002/9780470187326.ch3

Cited by 11 publications

(17 citation statements)

References 745 publications

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“…The loss of •C 4 F 9 (i.e., m / z = 436.98 → 217.99) and of C 4 F 10 ( m / z = 436.98 → 198.99) suggested a C 4 F 9 substituent, based on the analogy that •CH 3 and CH 4 losses are observed for isopropyl-substituted phenyls . Losses of •CF 3 ( m / z = 436.98 → 367.97 and 217.99 →149.00), of •OCF 3 ( m / z = 217.99 → 133.00) and of (•CF 3 +CO) ( m / z = 217.99 → 121.00) indicate a CF 3 O substituent based on analogy that CH 3 O substituted aromatic compounds lose •CH 3 , •OCH 3 , − and (•CH 3 +CO). ,,, Given these two likely substituents, the most likely core structure is a substituted perfluorinated imidazole-(CF 3 O)(C 4 F 9 )(CF 3 ), which is supported by MS/MS experiments (Figure S13.2). Given uncertainties and the number of isomers, the structure for this class of substances is generally proposed as perfluorinated N -heterocycles (CL = 3; Table ).…”

Section: Resultsmentioning

confidence: 99%

Nontarget Mass Spectrometry Reveals New Perfluoroalkyl Substances in Fish from the Yangtze River and Tangxun Lake, China

Liu

Qian

et al. 2018

Environ. Sci. Technol.

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Nontarget high-resolution mass spectrometry (Nt-HRMS) has been proven useful for the identification of unknown poly- and perfluoroalkyl substances (PFASs) in commercial products and water, but applications to biological samples are limited. China is the major PFAS-manufacturing nation; thus, here, we adapted our Nt-HRMS methods to fish collected from the Yangtze River and Tangxun Lake to discover potentially bioaccumulative PFASs in aquatic organisms destined for human consumption. In addition to traditional PFASs, over 330 other fluorinated analytes belonging to 10 classes of PFASs were detected among the pooled fish livers, including 6 sulfonate classes, 2 amine classes, 1 carboxylate class, and 1 N-heterocycle class. One class was detected in samples from both locations, 8 classes were detected exclusively in Tangxun Lake fish, and 1 class was detected exclusively in Yangtze River fish, 10 km downstream of a fluorochemical manufacturing site where we first reported these substances in wastewater 3 years ago. Overall, 4 of the PFAS classes (>165 analytes) are reported for the first time here. Wider monitoring and toxicological testing should be a priority for understanding the health risks posed to people and wildlife exposed to these substances.

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Section: Resultsmentioning

confidence: 99%

Nontarget Mass Spectrometry Reveals New Perfluoroalkyl Substances in Fish from the Yangtze River and Tangxun Lake, China

Liu

Qian

et al. 2018

Environ. Sci. Technol.

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“…However, the α-hydrogens of pyrroles are known to readily exchange under acidic conditions. 26 It is therefore not clear whether the deuterium atoms were replaced by hydrogens during the formation of the compounds or the exchange occurred during their isolation/analysis. In general, the collected MS data including fragmentation and isotopic patterns were found to be in excellent agreement with the proposed structures.…”

Section: ■ Materials and Methodsmentioning

confidence: 99%

Allium Discoloration: Color Compounds Formed during Pinking of Onion and Leek

Kubec

Urajová

Lacina

et al. 2015

J. Agric. Food Chem.

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Structures and formation pathways of compounds responsible for pink discoloration of onion and leek were studied. A procedure was developed for the isolation and purification of the color compounds from various model systems and their identification by HPLC-DAD-MS/MS. In total, structures of 15 major color compounds were tentatively determined. It was found that the pigment is a complex mixture of highly conjugated species composed of two N-substituted 3,4-dimethylpyrrole-derived rings linked by either a methine or a propenylidine bridge. These two-ring units are further modified by various C1- and C3-side chains. Experiments with isotope-labeled thiosulfinates revealed that the methine bridge and C1-side chains originate from the methyl group of methiin, whereas the C3 units are derived from the propenyl group of isoalliin.

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“…Although intermediates of this type are omnipresent in nature, e.g., in the biosynthesis of porphyrins, their application in organic synthesis has been rather limited, which most likely can be attributed to their difficult preparation and synthetic handling. On the basis of their electron-rich character pyrrolyl carbinols are notoriously plagued by competing oligomerizations and oxidations . In our synthesis of [1,2- a ]-fused pyrroles, however, we have been able to tame this reactivity by introducing an electron-withdrawing group at the pyrrole-5-position …”

mentioning

confidence: 95%

“…On the basis of their electron-rich character pyrrolyl carbinols are notoriously plagued by competing oligomerizations and oxidations. 15 In our synthesis of [1,2-a]-fused pyrroles, however, we have been able to tame this reactivity by introducing an electron-withdrawing group at the pyrrole-5position. 13 Building on this experience, we envisioned extending this methodology toward a synthesis of cyclopenta [b]pyrroles by starting from 1H-pyrrol-3-yl carbinol (Scheme 1B).…”

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confidence: 99%

Brønsted-Acid-Catalyzed (3+2)-Cycloannulation of In-Situ-Generated 3-Methide-3H-pyrroles: Asymmetric Synthesis of Cyclopenta[b]pyrroles

2020

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An organocatalytic, highly enantioselective addition of cyclic enamides to in-situ-generated 3-methide-3H-pyrroles with subsequent cyclization and elimination has been developed. This protocol represents a novel and straightforward route toward polycyclic cyclopenta[b]pyrroles with high yields and excellent enantioselectivity. Central to the success is the formation of a chiral, hydrogen-bonded 3-methide-3H-pyrrole upon phosphoric-acid-catalyzed dehydration of the starting 1H-pyrrol-3-yl carbinol that reacts with the enamide in a stepwise cycloannulation process.

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Reactivity of the 1 H ‐Pyrrole Ring System

Cited by 11 publications

References 745 publications

Nontarget Mass Spectrometry Reveals New Perfluoroalkyl Substances in Fish from the Yangtze River and Tangxun Lake, China

Nontarget Mass Spectrometry Reveals New Perfluoroalkyl Substances in Fish from the Yangtze River and Tangxun Lake, China

Allium Discoloration: Color Compounds Formed during Pinking of Onion and Leek

Brønsted-Acid-Catalyzed (3+2)-Cycloannulation of In-Situ-Generated 3-Methide-3H-pyrroles: Asymmetric Synthesis of Cyclopenta[b]pyrroles

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