Studies on the Total Synthesis of Lactonamycin: Synthesis of the Fused Pentacyclic B–F Ring Unit

Jacques, Sylvain; Michaelis, Simon; Gebhardt, Björn; Blum, Andreas; Lebrasseur, Nathalie; Larrosa, Igor; White, Andrew J. P.; Barrett, Anthony G. M.

doi:10.1002/ejoc.201101317

Cited by 8 publications

(4 citation statements)

References 35 publications

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“…The residue was purified by column chromatography (Hexane:Ethyl acetate = 1:1, R f = 0.3) to obtain 7 as a white solid (17.4 g, 88%). 1 H NMR (300 MHz, DMSO- d 6 ): δ 6.87 (s, 2H), 5.12–5.08 (t, J = 6.0 Hz, 2H), 4.52–4.50 (d, J = 6.0 Hz, 4H), 3.72 (s, 3H), 3.61 (s, 3H) (the NMR spectra were in agreement with those reported) …”

Section: Methodssupporting

confidence: 87%

“…1 H NMR (300 MHz, DMSO-d 6 ): δ 6.87 (s, 2H), 5.12−5.08 (t, J = 6.0 Hz, 2H), 4.52−4.50 (d, J = 6.0 Hz, 4H), 3.72 (s, 3H), 3.61 (s, 3H) (the NMR spectra were in agreement with those reported). 53 1,3-Bis(bromomethyl)-2,5-dimethoxybenzene (1c). A solution of 7 (4.0 g, 20.18 mmol) in DCM (50 mL) was cooled to 0 °C and added phosphorus tribromide (12.02 g, 44.4 mmol).…”

Section: ■ Experimental Sectionsupporting

confidence: 87%

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Photoinduced DNA Interstrand Cross-Linking by Benzene Derivatives: Leaving Groups Determine the Efficiency of the Cross-Linker

Fan

Peng

2020

J. Org. Chem.

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We have synthesized and characterized two small libraries of 2-OMe or 2-NO2-benzene analogues 2a–i and 3a–i containing a wide variety of leaving groups. Irradiation of these compounds at 350 nm generated benzyl radicals that were spontaneously oxidized to benzyl cations directly producing DNA interstrand cross-links (ICLs). Compounds with a 2-methoxy substituent showed a faster cross-linking reaction rate and higher ICL efficiency than the corresponding 2-nitro analogues. Apart from the aromatic substituent, the benzylic leaving groups greatly affected DNA cross-linking efficiency. Higher ICL yields were observed for compounds with OCH3 (3b), OCH2Ph (3d), or Ph3P+ (3i) as leaving groups than those containing OAc (3a), NMe2 (3e), morpholine (3f), OCH2CHCH2 (3c), SPh (3g), or SePh (3h). The heat stability study of the isolated ICL products indicated that dGs were the preferred alkylation sites in DNA for the benzyl cations produced from 2a–i, 3c, and 3e–i while 3a (L = OAc), 3b (L = OMe), and 3d (L = OCH2Ph) showed a similar photoreactivity toward dGs and dAs. Although the photogenerated benzyl cations alkylated dG, dC, and dA, ICL assay with variation of DNA sequences showed that the ICL reaction occurred with opposing dG/dC but not with staggered dA/dA.

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Section: Methodssupporting

confidence: 87%

Section: ■ Experimental Sectionsupporting

confidence: 87%

Photoinduced DNA Interstrand Cross-Linking by Benzene Derivatives: Leaving Groups Determine the Efficiency of the Cross-Linker

Fan

Peng

2020

J. Org. Chem.

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“…The results of the studies to obtain the methylene‐bridged bisnaphthalene 35 are summarized in Table and Scheme . The first experiments for the Suzuki coupling reaction of the antagonistic substituted naphthalenes were conducted by using a boronic ester . These organoboron compounds exhibit rather low nucleophilicity, which results in low reactivity in Suzuki couplings.…”

Section: Resultsmentioning

confidence: 99%

Synthesis of Methylene‐Bridged Bisnaphthalenes as Building Blocks for Push–Pull Substituted Pentacenes

2017

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The use of cross‐coupling reactions for the synthesis of methylene‐bridged bisnaphthalenes bearing two nitro groups on one naphthalene and two amino groups on the other has been investigated. A Hauser–Heck reaction was used to prepare the substituted naphthalene building blocks. It was not possible to install a transmetallating function in the benzylic position due to side reactions with the nitro and the amino groups. A successful Suzuki reaction was achieved by using naphthyl trifluoroborates and bromomethyl naphthalenes. The resulting dinaphthyl methanes could be useful for the synthesis of push–pull substituted pentacenes.

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“…This unique structure has attracted numerous synthetic efforts. The first synthetic study was undertaken by Danishefsky in 2000, who completed the total synthesis of lactonamycinone ( 3 ) in 2003. − Subsequent studies by Deville and Behar, Kelly, , Barrett, − and Parrain and Commeiras have been undertaken. Only two groups have thus far completed the synthesis of lactonamycin; the first was Tatsuta et al in 2010 and the second was Nakata and Saikawa et al in 2013. , …”

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confidence: 99%

An Approach to the Core of Lactonamycin

et al. 2017

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Studies on the Total Synthesis of Lactonamycin: Synthesis of the Fused Pentacyclic B–F Ring Unit

Abstract: This paper describes an approach towards the total synthesis of lactonamycin with the elaboration of a key pentacyclic unit. Key steps include the synthesis of benzyl bromide 8 in eight steps and 23 % overall yield starting from 4-meth-

Cited by 8 publications

References 35 publications

Photoinduced DNA Interstrand Cross-Linking by Benzene Derivatives: Leaving Groups Determine the Efficiency of the Cross-Linker

Photoinduced DNA Interstrand Cross-Linking by Benzene Derivatives: Leaving Groups Determine the Efficiency of the Cross-Linker

Synthesis of Methylene‐Bridged Bisnaphthalenes as Building Blocks for Push–Pull Substituted Pentacenes

An Approach to the Core of Lactonamycin

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