The chemistry of enediynes, enyne allenes and related compounds

Grissom, Janet Wisniewski; Gunawardena, G. U.; Klingberg, Detlef; Huang, D.

doi:10.1016/0040-4020(96)00016-6

Cited by 421 publications

(154 citation statements)

References 262 publications

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“…1 A case in point is the kedarcidin chromophore 1, which possesses an elaborate ansamacrocyclic bridge and two unusual 2-deoxysugar components ( Fig. 1).…”

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Synthesis of the entire carbon framework of the kedarcidin chromophore aglycon

et al. 2007

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“…1 A case in point is the kedarcidin chromophore 1, which possesses an elaborate ansamacrocyclic bridge and two unusual 2-deoxysugar components ( Fig. 1).…”

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confidence: 99%

Synthesis of the entire carbon framework of the kedarcidin chromophore aglycon

et al. 2007

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“…After being stirred at 0°C for 30 min, the reaction was quenched with saturated aq. NH 4 Cl and diluted with EtOAc. The organic layer was separated, washed with brine, dried over MgSO 4 , and evaporated in vacuo.…”

Section: Methodsmentioning

confidence: 99%

“…The combined organic layer was washed with brine, dried over MgSO 4 and evaporated in vacuo. The residue was purified by silica gel column chromatography (hexane-EtOAc) to give carbamate 4 (1.40 g, 98%) as a colorless oil.…”

Section: Methodsmentioning

confidence: 99%

“…[2][3][4][5][6][7][8] To date, a number of polyenyne compounds, including both natural 2,4,7) and artificial products, 3,7,8) have been synthesized to evaluate their reactivity and to develop more potent and selective antitumor agents, however, modification of the conjugated enyne core structures has not been well investigated. We focused on nonconjugated polyenyne systems and found that nonconjugated aryl-ynes and aryl-yne-allenes undergo thermal cycloaromatization (CA) reactions [9][10][11][12][13][14] while cleaving DNA.…”

Section: Notesmentioning

confidence: 99%

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Thermal Cyclization of Nonconjugated Aryl-Yne-Carbodiimide Furnishing a Dibenzonaphthyridine Derivative

Kimura

Torikai

Ueda

2009

CHEMICAL & PHARMACEUTICAL BULLETIN

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NotesConjugated enyne compounds have received considerable attention in the broad field of chemistry, because of their unique cyclization reactions affording aromatized products by way of radical intermediates capable of DNA cleavage. [2][3][4][5][6][7][8] To date, a number of polyenyne compounds, including both natural 2,4,7) and artificial products, 3,7,8) have been synthesized to evaluate their reactivity and to develop more potent and selective antitumor agents, however, modification of the conjugated enyne core structures has not been well investigated. We focused on nonconjugated polyenyne systems and found that nonconjugated aryl-ynes and aryl-yne-allenes undergo thermal cycloaromatization (CA) reactions [9][10][11][12][13][14] while cleaving DNA. [15][16][17] Thus, as a next goal, we set a reagent-free thermal isomerization of nonconjugated aryl-yne systems, which involves homolyses of carbon-nitrogen (C-N) unsaturated bonds to afford useful azaaromatic compounds via a domino radical reaction. 18)As target polycyclic aromatic compounds, we focused on dibenzonaphthyridine derivatives, which have never been synthesized via thermal isomerization of aryl-ynes, despite their fascinating and intriguing pharmacological properties. [19][20][21][22][23] In order to provide a novel synthetic methodology of dibenzonaphthyridines, we planned to examine the CA reactions of nonconjugated aryl-yne-carbodiimides (AYCs). Carbodiimide is considered to be an aza-equivalent of allene, and more importantly, canceled dipole moments of C-N bonds are expected to facilitate the homolytic cleavage of the C-N bond to form radical species. The Wang [24][25][26][27][28] and the Schmittel 29-31) groups have recently reported the thermal CA of AYCs, but their scopes are limited to conjugated systems, whose electronic and steric environments are far different from nonconjugated ones, and which would be unable to provide dibenzonaphthyridine derivatives. Herein, we report the synthesis and the CA reactions of AYCs 1 and 2.As AYC substrates, we selected two compounds (Fig. 1). One possesses a conjugated aryl-yne and a dependent carbodiimide moiety (1) and the other is equipped with a conjugated aryl-carbodiimide and a dependent alkyne moiety (2).Synthesis of AYC 1 commenced with 2-bromobenzylamine hydrochloride 3 (Chart 1). After tert-butoxycarbonyl (Boc) protection of 3 (98%), the resulting bromobenzene 4 was coupled with ethynylbenzene 5 under Sonogashira-Hagihara conditions 32,33) to give 6 in good yield (90%). 34) After removal of the Boc group with trifluoroacetic acid (TFA), amine 7 was converted to the corresponding thiourea 8 by the action of phenyl isothiocyanate in refluxing acetone (69%).35) Desulfurization of 8 by treatment with methanesulfonyl chloride (MsCl) in the presence of triethylamine and 4-dimethylaminopyridine (DMAP) 36) successfully furnished carbodiimide 1 (84%). As for AYC 2, the synthesis was initiated with 2-aminobenzylalcohol 9. Oxidation of alcohol 9 with MnO 2 into aldehyde, followed by addition of phenyleth...

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“…Some important areas of DNA and RNA cleavage were not addressed in this issue, including the enediynes, which have been extensively reviewed in recent years. [15][16][17][18] I am grateful to all of the authors for their outstanding contributions and to the Editorial Staff of Chemical Reviews and the ACS publications division for all of their help. I acknowledge NSF and the donors of the Petroleum Research Fund, administered by the American Chemical Society, for partial support.…”

Section: Introduction To Rna/dna Cleavagementioning

confidence: 99%