Intramolecular cyclisations of biphenyl-2-carboxyl radicals: evidence for a II-state aroyloxyl radical

Glover, Stephen A.; Golding, Stephen L.; Goosen, A.; McCleland, Cedric W.

doi:10.1039/p19810000842

Cited by 27 publications

(16 citation statements)

References 1 publication

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Ott and Zinke postulated the possible formation of even more complex 1-oxa-coronen-2-one while oxidizing 7,8dicarboxybenzo[ghi]perylene. 99 Scholl reaction is also commonly used for preparation of polycyclic aromatic hydrocarbons. 97 Minabe and co-workers used Bayer-Villiger oxidation of 4-oxocyclopenta[def]phenanthrene for preparation of unsubstituted 4-oxapyren-5-one.…”

Section: Scheme 47mentioning

confidence: 99%

π-Expanded coumarins: synthesis, optical properties and applications

et al. 2015

View full text Add to dashboard Cite

Coumarins fused with other aromatic units have recently emerged as a hot topic of research. Their synthesis is partly based on classical methodologies such as Pechmann reaction or Knoevenagel condensation, but it also sparked the discovery of completely new pathways. In very recent years so-called vertically-expanded coumarins were synthesized, effectively expanding the portfolio of existing architectures. A subtle relationship exists between the structure of fused coumarins and their optical properties. Although absorption of UV-radiation and light is unifying theme among these π-expanded coumarins, the fluorescence properties strongly depend on the structure. The mode of fusion, the type of additional ring and the presence of electron-donating and electron-withdrawing substituents all influence the photophysical parameters. Recent advances made it possible to modulate their absorption from 300 nm to 550 nm, resulting in new coumarins emitting orange light. This review serves as a guide through both synthesis strategies and structure-property relationship nuances. Strong intramolecular charge-transfer character made it possible to reach suitable values of two-photon absorption crosssection. Photophysical advantages of π-expanded coumarins have been already utilized in fluorescence probes and two-photon excited fluorescence microscopy.

show abstract

Section: Scheme 47mentioning

confidence: 99%

π-Expanded coumarins: synthesis, optical properties and applications

et al. 2015

View full text Add to dashboard Cite

show abstract

“…Compound 20 , with gem -dimethyl substitution on ring-A, showed significant cytotoxic activity (Table 1), and was chosen for further modification to study the functions of the hydroxyl and carboxylic acid groups ( 21 – 28 ). The selective methylation of the hydroxy group on 20 was achieved by the addition of MeI and 18-crown-6 ether to the crude hydrolysis mixture of 17 without work-up 14. The resulting carboxylic acid 21 was converted to methyl ester 22 with thionyl chloride and MeOH at room temperature.…”

mentioning

confidence: 99%

Antitumor agents 269. Non-aromatic ring-A neotanshinlactone analog, TNO, as a new class of potent antitumor agents

Dong

Shi

Nakagawa‐Goto

et al. 2009

Bioorganic & Medicinal Chemistry Letters

View full text Add to dashboard Cite

Tetrahydroneotanshinlactone (TNT) and tetrahydronaphthalene-1-ol (TNO) derivatives were designed, synthesized, and evaluated for cytotoxic activity. The TNO derivatives were found to be a promising novel class of in vitro antitumor agents. The cyclohexene ring-A could dramatically affect the antitumor activity and selectivity. Compound 20 showed the highest potency with ED50 values of 0.7 and 1.7 µM against SK-BR-3 and ZR-75-1 breast cancer cell lines, respectively.

show abstract

“…3b), and the formation of the lactone from non-substituted biaryls (control experiments, ESI, page S13†) support this proposal. Carboxyl radical intermediate A induces dearomatization by intramolecular cyclization to form intermediate B in both systems, where the twisted conformation promotes the cyclization 28. From this point, the two pathways diverge.…”

Section: Resultsmentioning

confidence: 99%

“…However, when Ar 2 was exchanged for a naphthyl group, a moderate yield of the product ( 14 ) was obtained. Dimethoxy-substituted arenes (Ar 1 ) are another type of challenging substrates, as ipso substitution of the methoxy group can occur 28. In this case, moderate to excellent yields of spirolactones were obtained using condition A ( 15–17 ).…”

Section: Resultsmentioning

confidence: 99%

“…A few protocols in which nitrogen-based radical or nitrenium ion dearomatization led to spiro-formation have been developed 24–27. Those transformations were driven by the low activation entropy of the N-centered radicals for the cyclization to 5-membered products 28. In comparison, the carboxyl motif is readily available, however, strong preferences for carboxyl radicals to form 6-membered products have been reported by Gonzales and co-workers, who found that the blockage of the ortho -position of the aryl ring by a methoxy group led to ipso substitution instead of spirolactonization 29…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation