The syntheses of large-ring compounds

Roxburgh, Craig J.

doi:10.1016/0040-4020(95)00629-m

Cited by 110 publications

(40 citation statements)

References 208 publications

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“…These gave the [1,4] oxazepinoA C H T U N G T R E N N U N G [5,4-a]isoindole derivatives in good yields. Photoreactions of 1 (0.025 mol dm…”

Section: Resultsmentioning

confidence: 96%

“…1 H NMR spectra were recorded on a Bruker DPX 300 spectrometer with CDCl 3 as the solvent unless otherwise specified. 13 C NMR spectra were measured on a Bruker Avance-400 spectrometer at 100 MHz with CDCl 3 as the solvent.…”

Section: Methodsmentioning

confidence: 99%

“…[1] The formation of medium rings (7-9-membered rings) is particularly difficult because of a combination of unfavorable enthalpic and entropic changes during the cyclization process.…”

Section: Introductionmentioning

confidence: 99%

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Intermolecular Photocyclizations of N‐(ω‐Hydroxyalkyl)tetrachlorophthalimide with Alkenes Leading to Medium‐ and Large‐Ring Heterocycles—Reaction Modes and Regio‐ and Stereoselectivity of the 1,n‐Biradicals

Shen

Yang

Chen

et al. 2010

Chemistry A European J

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A new photocyclization strategy by using intermolecular tandem reactions between N-(omega-hydroxyalkyl)-4,5,6,7-tetrachlorophthalimides (1, 2, and 3) and a series of acyclic and cyclic alkenes is reported. Electron transfer of the triplet-excited phthalimide with the alkene and regioselective trapping of the alkene cation radical by the hydroxyl group at the phthalimide side chain gives a triplet 1,n-biradical, which after intersystem crossing (ISC) leads to regio- and diastereoselective synthesis of polycyclic heterocycles with an N,O-containing medium to large ring. Regio- and diastereoselectivity in the cyclizations are clarified by unambiguous steric structure assignments of the products by X-ray diffraction or extensive 2D NMR measurements. The diastereoselectivity is decided by the stereochemical course of the ISC process of the triplet 1,n-biradicals. These intermolecular photoreactions also furnish a new strategy to generate triplet 1,n-biradicals. Therefore, in photoreactions of 1 and 2 with phenylcyclohexene, the unprecedented stereoselective formation of products by intramolecular hydrogen-atom transfer in the 1,n-biradical intermediate was found (9 and 23). These facts provide direct verification to the reaction pathways of the 1,n-biradicals and give a new insight into the factors deciding reaction-pathway partitioning and stereoselectivity.

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“…These gave the [1,4] oxazepinoA C H T U N G T R E N N U N G [5,4-a]isoindole derivatives in good yields. Photoreactions of 1 (0.025 mol dm…”

Section: Resultsmentioning

confidence: 96%

Section: Methodsmentioning

confidence: 99%

See 1 more Smart Citation

Intermolecular Photocyclizations of N‐(ω‐Hydroxyalkyl)tetrachlorophthalimide with Alkenes Leading to Medium‐ and Large‐Ring Heterocycles—Reaction Modes and Regio‐ and Stereoselectivity of the 1,n‐Biradicals

Shen

Yang

Chen

et al. 2010

Chemistry A European J

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“…52,53 As principais características das reações com Bu 3 SnH, responsáveis pela sua ampla aplicação, são a relativa simplicidade do ponto de vista operacional; a ciclização ocorre sem alteração da configuração dos estereocentros de precursores quirais; a maioria dos grupos funcionais é inerte ao reagente. 54,55 No entanto, há inconvenientes: toxicidade, dificuldade em eliminar os resíduos de estanho dos produtos obtidos e formação de produtos acíclicos reduzidos.…”

Section: Síntese De Macrociclos Por Reação De Carbociclização Radicalunclassified

Macrolactamas bioativas e síntese de macrociclos por reação de carbociclização radicalar mediada por hidreto de tri-n-butilestanho

Faraco¹,

Pires²,

Rocha³

et al. 2008

Quím. Nova

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Recebido em 27/2/07; aceito em 27/9/07; publicado na web em 13/8/08 BIOACTIVE MACROLACTAMS AND SYNTHESIS OF MACROCYCLES BY TRI-N-BUTYLTIN HYDRIDE-MEDIATED RADICAL CARBOCYCLIZATION REACTION. This review presents natural, semi-synthetic and synthetic bioactive macrolactams and their structure-activity relationships when available. For macrolactams in clinical use the advantages and disadvantages in relation to other drugs are presented, and for synthetic macrolactams the method used in the cyclization is showed. Regarding macrocyclic synthesis by the tri-n-butyltin hydride-mediated radicalar carbocyclization reaction the precursor, the reaction conditions, products and yields, mechanism and cyclization mode are discussed.Keywords: bioactive macrolactams; radical carbocyclization; macrocyclization. introduçãoOs macrociclos apresentam importantes atividades biológicas e muitos deles, ou seus derivados, são usados como fármacos (eritromicina, ciclosporina, vancomicina e anfotericina B).1-3 As atividades biológicas dos macrociclos, substâncias com enorme variedade estrutural, são atribuídas, em parte, a uma característica comum: a restrição conformacional em relação a compostos de cadeia aberta. 2,4Entre os macrociclos que são agentes bioativos encontram-se as macrolactamas, cujas atividades biológicas se devem, em parte, ao fato de serem macrociclos e também amidas. Em um trabalho publicado recentemente, no qual são apresentados dados relativos a 128 candidatos a fármacos em desenvolvimento em três grandes indústrias farmacêuticas, é relatado que 12% das reações realizadas na síntese das 128 substâncias são de acilação, especialmente N-acilações. Os autores não se surpreendem com esse dado, uma vez que as amidas estão presentes em um grande número de fármacos. Além disso, de 53 fármacos que, em 2003, foram responsáveis pela arrecadação acima de 1 bilhão de dólares, 9 apresentam o grupo amida e 3, o grupo sulfonamida. 5Tendo em vista sua importância, as macrolactamas vêm sendo amplamente estudadas sob vários aspectos: isolamento e elucidação estrutural de produtos naturais, síntese, modificações moleculares, estudos de relação estrutura química/atividade biológica, mecanismo de ação e triagem clínica. MacrolactaMas naturais e seMi-sintéticas coM atividade biológicaDiversos depsipeptídeos macrocíclicos apresentam atividade biológica: criptoficina A (atividade antitumoral 6 ), hapalosina (atividade citotóxica leve 7 ) e estevastelina B (inibe ativação de células T e B 8 ) (Esquema 1). Outros depsipeptídeos cíclicos, isolados de cianobactéria marinha (Lyngbya majuscula) e denominados lingbiabelinas A e B (Esquema 1), apresentam atividade contra células tumorais. 9,10A indolactama-V e benzolactama-V8 (Esquema 2), de 9 e 8 membros respectivamente, ligam-se à proteína quinase C ativando-a para a promoção de tumores. Esta atividade parece estar diretamente

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“…[1] Indeed, many complex natural products and drugs are cyclic in nature, and a ring closure reaction is very often the crucial step in a multistep synthesis. In connection with our ongoing project on the synthesis of macrocycles with an endo aryl-aryl bond, [2] we examined the cyclization of diamide 1 under modified Miyaura-Suzuki conditions.…”

mentioning

confidence: 99%

One‐Pot Synthesis of Polyheterocycles by a Palladium‐Catalyzed Intramolecular N‐Arylation/CH Activation/Aryl–Aryl Bond‐Forming Domino Process

2003

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There has been considerable interest in developing novel cyclization methodologies for organic synthesis.[1] Indeed, many complex natural products and drugs are cyclic in nature, and a ring closure reaction is very often the crucial step in a multistep synthesis. In connection with our ongoing project on the synthesis of macrocycles with an endo aryl-aryl bond, [2] we examined the cyclization of diamide 1 under modified Miyaura-Suzuki conditions.[3] However, heating a solution of 1 in DMSO in the presence of [PdCl 2 (dppf)] (5.0 mol %; dppf = 1,1'-bis(diphenylphosphanyl)ferrocene), KOAc (3.0 equiv), and bis-(pinacolato)diboron (2, 1.2 equiv) did not provide macrocycle 4. Instead, polyheterocycle 3 was produced in about 50 % yield (Scheme 1). Formally, one C aryl À N and one C aryl À C aryl bond were created with concurrent formation of a nine-membered and a six-membered ring. While intramolecular N-arylation leading to five-and six-membered rings is well-established, attempts to access mediumsized and macrocyclic ring systems by the same reaction were, to the best of our knowledge, unsuccessful. [4,5] Intrigued by the potential synthetic power of this novel catalytic domino process, [6] we set out to examine in detail this unprecedented transformation and report herein our preliminary results.

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The syntheses of large-ring compounds

Cited by 110 publications

References 208 publications

Intermolecular Photocyclizations of N‐(ω‐Hydroxyalkyl)tetrachlorophthalimide with Alkenes Leading to Medium‐ and Large‐Ring Heterocycles—Reaction Modes and Regio‐ and Stereoselectivity of the 1,n‐Biradicals

Intermolecular Photocyclizations of N‐(ω‐Hydroxyalkyl)tetrachlorophthalimide with Alkenes Leading to Medium‐ and Large‐Ring Heterocycles—Reaction Modes and Regio‐ and Stereoselectivity of the 1,n‐Biradicals

Macrolactamas bioativas e síntese de macrociclos por reação de carbociclização radicalar mediada por hidreto de tri-n-butilestanho

One‐Pot Synthesis of Polyheterocycles by a Palladium‐Catalyzed Intramolecular N‐Arylation/CH Activation/Aryl–Aryl Bond‐Forming Domino Process

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