Carbenes. Reactive Intermediates Containing Divalent Carbon.

Chinoporos, Efthimios

doi:10.1021/cr60223a002

Cited by 54 publications

(10 citation statements)

References 99 publications

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“…In the case of [l,n]paracyclophanes the synthetically available member [2131 with the shortest polymethylene chain linking the 4-and #-positions of the diphenylmethane group is the one with n = 7, but spectral anomalies[z131 appear also for n = 8 and 9 and are noticeable even for n = 12, indicating that the saturated chain draws the two benzene rings closer together and even deforms them. The limiting ring size for restricted rotation of the phenylene group in paracyclophanes is indicated by the resolution ~141 of an aromatic carboxylic acid derivative of [3,4] However, such chemical and spectroscopic studies have been concerned mainly with the stereochemistry of parts of the ring, for example the question of planarity of chromophoric conjugated groups, or with transannular interactions of two such groups, or with the dependence of synthetic yield and resolvability on ring size, and no conclusions about the shape of the whole ring as such have been drawn.…”

Section: Rings Containing Phenylene Groupsmentioning

confidence: 99%

“…Crystal structure of [2,2]paracyclophane [ZIOI that the strain is well distributed over the whole molecule and that the distance between the two aromatic planes, which is normally 3.4 8, (graphite), is here 3.09 8, in the middle and only 2.83 A between linked atoms. The [3,3]paracyclophane has somewhat more freedom, and the strong x-electron repulsion causes the aromatic rings not only to bend but also to be displaced from a centered position, (30) (Fig. 42) repulsion is diminished by complex formation on one side [2121, the structure presumably falls back into the centered position whereby bond angle strain is released; this is assumedr2121 to be the driving force for the exceptionally strong tendency of (30) for complex formation with tetracyanoethylene.…”

Section: Rings Containing Phenylene Groupsmentioning

confidence: 99%

“…In the case of [l,n]paracyclophanes the synthetically available member [2131 with the shortest polymethylene chain linking the 4-and #-positions of the diphenylmethane group is the one with n = 7, but spectral anomalies[z131 appear also for n = 8 and 9 and are noticeable even for n = 12, indicating that the saturated chain draws the two benzene rings closer together and even deforms them. The limiting ring size for restricted rotation of the phenylene group in paracyclophanes is indicated by the resolution ~141 of an aromatic carboxylic acid derivative of [3,4] Highly Heterogeneous Ring Systems Ring systems composed of several different chemical groups (aromatic nuclei, multiple bonds, carbonyl groups, heteroatoms, etc.) have been extensively studied.…”

Section: Rings Containing Phenylene Groupsmentioning

confidence: 99%

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Conformational Aspects of Many‐Membered Rings

Dale

1966

Angew. Chem. Int. Ed. Engl.

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obtained in anhydrous dimethylformamide at 150 'C (Scheme 2,d). e) R e a c t i o n with AminesPoly-y-hydroxycrotonolactone reacts with amines in aqueous media at 20 to 50°C to give the ammonium salt of the polymeric y-hydroxy acid (see Scheme 2,el). In organic solvents, e.g. in an excess of the amine, higher reaction temperatures are required, and the polymeric y-hydroxy carboxamide is then formed (Scheme 2,ez). f) R e d u c t i o n with L i t h i u m T e t r a h y d r i d o a l u m i n a t e Polymeric crotonolactone can be smoothly reduced with LiAIH4 in tetrahydrofuran to give a water-soluble polymer of 2-butene-l,4-diol (Scheme 2,f). We are grateful to Professor Korte for his interest in this work. The stereochemistry of the various chemical groupings which constitute the structural units of ring systems isfirst reviewed. It is then shown that the strain-free possibilities even of large rings are restricted, and that the ring conformations theoretically derived generally correspond to those found by physical methods. Variations of physical properties and of cyclization yield in homologous series are explained on a conformational basis.[5] J. B. Hendrickson, J. Amer. chem. SOC. 83, 4537 (1961). [6] Earlier summaries: J. D. Dunirz and V. Prelog, Angew. Chem. 72, 896 (1960).

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Section: Rings Containing Phenylene Groupsmentioning

confidence: 99%

Section: Rings Containing Phenylene Groupsmentioning

confidence: 99%

“…In the case of [l,n]paracyclophanes the synthetically available member [2131 with the shortest polymethylene chain linking the 4-and #-positions of the diphenylmethane group is the one with n = 7, but spectral anomalies[z131 appear also for n = 8 and 9 and are noticeable even for n = 12, indicating that the saturated chain draws the two benzene rings closer together and even deforms them. The limiting ring size for restricted rotation of the phenylene group in paracyclophanes is indicated by the resolution ~141 of an aromatic carboxylic acid derivative of [3,4] Highly Heterogeneous Ring Systems Ring systems composed of several different chemical groups (aromatic nuclei, multiple bonds, carbonyl groups, heteroatoms, etc.) have been extensively studied.…”

Section: Rings Containing Phenylene Groupsmentioning

confidence: 99%

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Conformational Aspects of Many‐Membered Rings

Dale

1966

Angew. Chem. Int. Ed. Engl.

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“…Nevertheless, they were first proposed as intermediates of chemical transformations in 1855. 1 Since then, carbenes have been found to be crucial intermediates in a wide range of organic transformations; 2 they have been used as ligands in organometallic chemistry 3 and have recently been employed as organocatalysts. 4,5 Carbenes exist in either the singlet or the triplet state.…”

Section: Introductionmentioning

confidence: 99%

Physical Nature of Differential Spin-State Stabilization of Carbenes by Hydrogen and Halogen Bonding: A Domain-Based Pair Natural Orbital Coupled Cluster Study

et al. 2019

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The variation in the singlet–triplet energy gap of diphenylcarbene (DPC) upon interaction with hydrogen (water and methanol) or halogen bond (XCF 3 , X = Cl, Br, I) donors to form van der Waals (vdW) complexes is investigated in relation to the electrostatic and dispersion components of such intermolecular interactions. The domain-based local pair natural orbital coupled cluster method, DLPNO–CCSD(T), is used for calculating accurate single–triplet energy gaps and interaction energies for both spin states. The local energy decomposition scheme is used to provide an accurate quantification to the various interaction energy components at the DLPNO–CCSD(T) level. It is shown that the formation of vdW adducts stabilizes the singlet state of DPC, and in the case of water, methanol, and ICF 3 , it reverses the ground state from triplet to singlet. Electrostatic interactions are significant in both spin states, but preferentially stabilize the singlet state. For methanol and ClCF 3 , London dispersion forces have the opposite effect, stabilizing preferentially the triplet state. The quantification of the energetic components of the interactions through the local energy decomposition analysis correlates well with experimental findings and provides the basis for more elaborate treatments of microsolvation in carbenes.

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“…10 Assim, uma série de (S)-alilaminas-(E)-clorovinílicas, 11, foi obtida com bons rendimentos (50 a 75%) e excelente estereosseletividade, 90 a 98%, em favor do isômero trans, sempre mantendo a configuração do aldeído de partida (Esquema 2). 10 Os halofórmios são, há tempo, conhecidos como fontes de dihalocarbenos 11 e íons tri-halometilas.…”

Section: Esquemaunclassified

Recentes aplicações sintéticas de compostos orgânicos tricloro(bromo)metila substituídos

Menezes¹,

Gallardo²,

Zucco³

2010

Quím. Nova

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Recebido em 1/7/10; aceito em 11/10/10; publicado na web em 16/11/10 RECENT SYNTHETIC APPLICATIONS OF TRICHLORO(BROMO)METHYL CONTAINING ORGANIC COMPOUNDS. This review presents the recent applications of some trihalomethyl carbinols, α,α,α-trihalogenated carbonyl compounds and trichloro(bromo)methyl-containing heterocycles, acting as high versatile synthetic precursors in organic chemistry, based on the last 10 years' literature.Keywords: trichloro(bromo)methyl compounds; synthetic applications. INTRODUÇÃO O grupo tricloro(bromo)metilaCompostos orgânicos contendo grupos -CCl 3 ou -CBr 3 em suas estruturas possuem diversas aplicações em diferentes áreas como bioquímica, agroquímica, produtos naturais, mas são reconhecidos, sobretudo, como reagentes altamente versáteis em síntese orgânica. O clorofórmio, por exemplo, o derivado mais simples contendo o grupo -CCl 3 , é um solvente de larga utilização em laboratórios. A Figura 1 mostra alguns compostos contendo o grupo -CX 3 , dotados de interessantes propriedades. O DDT, 1, é o inseticida mais conhecido da história.1 O composto piridínico 2 é relatado como um agente antitumoral 2 e o derivado arsênico 3 possui atividade antileucêmica.3 O grupo -CCl 3 é fundamental para a atividade biológica do Salubrinal, 4, uma molécula altamente eficaz na proteção de células sadias contra apoptose induzida por estresse excessivo e incorreto do retículo endoplasmático, fato responsável por importantes patologias como diabetes, Alzheimer e infecções virais. 4,5 Com relação aos derivados contendo o grupo -CBr 3 , destaca-se o agente neurotóxico 5.6 Já o composto 6 é um dos componentes da alga vermelha Asparagopsis Taxiformis, que apresenta atividade contra aldose redutase em bovinos. 7 Aplicações sintéticas de compostos orgânicos contendo -CX 3O desenvolvimento de novas estratégias e metodologias em sín-tese orgânica é um acontecimento recorrente e promissor de pesquisa em Química, e, nesse contexto, compostos orgânicos contendo o grupo -CX 3 (X = Cl, Br) têm sido citados na literatura como reagentes úteis e versáteis em diversas circuntâncias. Nesta revisão, serão apresentados exemplos relatados, principalmente na última década, envolvendo a utilização de tri-halometil carbinois (THMCs), compostos carbonilados α,α,α-tri-halogenados (CCTHs) e heterociclos contendo -CX 3 como precursores sintéticos de funções químicas variadas. Esses compostos atuam, muitas vezes, como peças fundamentais em estratégias de síntese de moléculas altamente elaboradas e de acentuada importância.Em 1934, Fuson e Bull publicaram um artigo de revisão acerca da reação do halofórmio, apontando, já naquela época, utilização dessa reação em análises qualitativas e quantitativas, suas aplicações em síntese e explicações mecanísticas. 8 De fato, a reação do halofórmio é uma das mais antigas na Química. Em 1822, Serulla, acidentalmente, verificou que o tratamento de etanol com hipoiodito, formado a partir de iodo em solução básica de hidróxido, levava à obtenção de iodofórmio e íon formato, por reação de oxidação do...

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Carbenes. Reactive Intermediates Containing Divalent Carbon.

Cited by 54 publications

References 99 publications

Conformational Aspects of Many‐Membered Rings

Conformational Aspects of Many‐Membered Rings

Physical Nature of Differential Spin-State Stabilization of Carbenes by Hydrogen and Halogen Bonding: A Domain-Based Pair Natural Orbital Coupled Cluster Study

Recentes aplicações sintéticas de compostos orgânicos tricloro(bromo)metila substituídos

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