1-methyl-1H-2-pyrrolethiol and -selenol. Synthesis, tautomerism and autotransformations

Vvedensky, Vladimir Y.; Brandsma, L.; Shtefan, E. D.; Трофимов, Б. А.

doi:10.1016/s0040-4020(97)10079-5

Cited by 7 publications

(3 citation statements)

References 5 publications

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“…The majority of syntheses involve electrophilic activation of an unsaturated bond followed by intramolecular ring closure . In contrast, only a few scattered methods have been reported for the synthesis of 3-seleno-furans and pyrroles, including a Paal−Knorr approach, unselective electrophilic selenation, and halogen−selenium exchange . These methods suffer from significant drawbacks, including limited scope of products, imperfect regioselectivity, and low yields.…”

Section: Resultsmentioning

confidence: 99%

Metal-Catalyzed 1,2-Shift of Diverse Migrating Groups in Allenyl Systems as a New Paradigm toward Densely Functionalized Heterocycles

et al. 2008

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A general, mild, and efficient 1,2-migration/cycloisomerization methodology toward multisubstituted 3-thio-, seleno-, halo-, aryl-, and alkyl-furans and pyrroles, as well as fused heterocycles, valuable building blocks for synthetic chemistry, has been developed. Moreover, regiodivergent conditions have been identified for C-4 bromo- and thio-substituted allenones and alkynones for the assembly of regioisomeric 2-hetero substituted furans selectively. It was demonstrated that, depending on reaction conditions, ambident substrates can be selectively transformed into furan products, as well as undergo selective 6-exo-dig or Nazarov cyclizations. Our mechanistic investigations have revealed that the transformation proceeds via allenylcarbonyl or allenylimine intermediates followed by 1,2-group migration to the allenyl sp carbon during cycloisomerization. It was found that 1,2-migration of chalcogens and halogens predominantly proceeds via formation of irenium intermediates. Analogous intermediate can also be proposed for 1,2-aryl shift. Furthermore, it was shown that the cycloisomerization cascade can be catalyzed by Brønsted acids, albeit less efficiently, and commonly observed reactivity of Lewis acid catalysts cannot be attributed to the eventual formation of proton. Undoubtedly, thermally induced or Lewis acid-catalyzed transformations proceed via intramolecular Michael addition or activation of the enone moiety pathways, whereas certain carbophilic metals trigger carbenoid/oxonium type pathway. However, a facile cycloisomerization in the presence of cationic complexes, as well as observed migratory aptitude in the cycloisomerization of unsymmetrically disubstituted aryl- and alkylallenes, strongly supports electrophilic nature for this transformation. Full mechanistic details, as well as the scope of this transformation, are discussed.

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Section: Resultsmentioning

confidence: 99%

Metal-Catalyzed 1,2-Shift of Diverse Migrating Groups in Allenyl Systems as a New Paradigm toward Densely Functionalized Heterocycles

et al. 2008

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“…However, if the quenching is performed using trimethylsilyl chloride instead of an acid, the obtained (trimethylsilyl)seleno derivative is stable and can give rise to the selenol upon treatment with acid. This methodology has been applied to N -methylpyrrole, its 2-selenol derivative being the most unstable. , Selenols or selenolates can give bisseleno compounds after oxidative treatment, , as shown in Scheme , where a 2-bromoindole such as compound 479 reacts with lithium methylselenide, affording the tyrosine kinase inhibitor bis(selenoindole) compound 481 , after oxidation of the selenol intermediate 480 130 …”

Section: Group 5 Metal-containing Heterocyclesmentioning

confidence: 99%

Metalated Heterocycles and Their Applications in Synthetic Organic Chemistry

2004

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“…Whereas there are numerous substituted benzenes amongst this list for which there are experimental measured enthalpies of formation (Li [375], CH 3 , NH 2 , OH, F, MgBr [376] (not quite the theorist's MgH), PH 2 , SH, Cl), only the methylpyrroles have so far attracted the experimental thermochemist's attention [377]. Studies of hydroxy and mercaptopyrroles are complicated by their energetically favorable tautomerism to the corresponding pyrrolone derivative [378][379][380].…”

Section: Issuementioning

confidence: 99%

Interplay of thermochemistry and Structural Chemistry, the journal (volume 18, 2007) and the discipline

Ponikvar

Liebman

2008

Struct Chem

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In this study, we relate the contents of the journal Structural Chemistry for the calendar year 2007 and thermochemistry. The year's articles were briefly summarized and a thermochemical comment written to supplement them. Frequently questions were asked and future research was suggested.Keywords Structural Chemistry Á Thermochemistry Á Thermodynamics Á Enthalpy of formation Á Enthalpy of phase change Á Enthalpy of reaction As practiced disciplines, structural chemistry and thermochemistry are very often unrelated. In this study, these disciplines are linked as relations are explicitly made using the contents of the journal Structural Chemistry (Vol. 18) for the calendar year 2007 as a scaffold for our analysis, for our selected articles in the discipline of structural chemistry. These studies have been reviewed by us, where we give them a thermochemical flavor. While this commentary is most generally written in terms of brief summaries of literature papers involving enthalpies of formation and/or reaction, not uncommonly we raise questions and even suggest possible future research. We are not, however, going to give a thermochemical slant on book reviews, honorary dedications, and obituaries although these works will be cited in our text.As such, this article is a sequel to our earlier related reviews of Structural Chemistry for the calendar years 2000 through 2004 [1-5]. Reviews for 2005 and 2006 are currently being prepared. Issue 1In the first article in the first issue of Structural Chemistry for 2007, Hargittai [6] asserted that while research is currently usually carried out in big groups, the most important ideas, observations and discoveries still belong to individuals who have to bring down dogmas or open entirely new areas in science. This may bring solace to the thermochemical community in which research groups are generally small, and the number of new practitioners sadly few.In the past decade, the crystal engineering of multidimensional arrays and networks containing metal ions has achieved considerable progress because of the increased interest in the potential utility of these compounds as zeolite-like materials [7-11], catalysts [12], or magnetic materials [13][14][15]. The thermochemistry of these species is complicated by their inherent complexity: however, estimation approaches of their key thermochemical quantities are increasingly reliable [16]. In the second article of this issue, by Wang et al. [17], the versatility of malonate dianion as a ligand for the construction of extended networks with different topologies dependent on the coordination geometry of the metal ion was discussed. The synthesis and structure of a novel malonate-bridged copper(II) compound in which copper(II) ions have two different coordination environments in a novel three-dimensional (3D) network was described. Metal malonates have been studied from a

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1-methyl-1H-2-pyrrolethiol and -selenol. Synthesis, tautomerism and autotransformations

Cited by 7 publications

References 5 publications

Metal-Catalyzed 1,2-Shift of Diverse Migrating Groups in Allenyl Systems as a New Paradigm toward Densely Functionalized Heterocycles

Metal-Catalyzed 1,2-Shift of Diverse Migrating Groups in Allenyl Systems as a New Paradigm toward Densely Functionalized Heterocycles

Metalated Heterocycles and Their Applications in Synthetic Organic Chemistry

Interplay of thermochemistry and Structural Chemistry, the journal (volume 18, 2007) and the discipline

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