A facile synthesis of naturally occurring binaphthoquinones: efficient oxidative dimerization of 4-alkoxy-1-naphthols using silver(II) oxide–40% nitric acid

Tanoue, Yasuhiro; Sakata, Kazunori; Hashimoto, Mamoru; Morishita, Shin-ichi; Hamada, Moritsugu; Kai, Norihisa; Nagai, Takeshi

doi:10.1016/s0040-4020(01)01130-9

Cited by 22 publications

(14 citation statements)

References 20 publications

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“…This finding is in agreement with the study conducted by Tanoue et al. on the oxidative coupling of 4‐substituted 1‐naphthols using a tenfold excess of AgO–40 %HNO 3 reagent 18. They found that electron‐withdrawing substituents deactivate the aromatic ring and inhibit the coupling process.…”

Section: Resultssupporting

confidence: 93%

Oxidative Coupling of 1‐Naphthols over Noble and Base Metal Catalysts

2013

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Bismuth‐promoted platinum catalysts were tested for the oxidative coupling of 2‐ and 4‐substituted 1‐naphthols at different temperatures and ambient pressure. The principal final products are the 3,3′‐substituted 1,1′‐binaphthalenylidene‐4,4′‐diones and the 4,4′‐substituted 2,2′‐binaphthalenylidene‐1,1′‐diones, respectively. Hydrogen peroxide was used as the oxidant. Only naphthols with electron‐donating substituents reacted. The corresponding binaphthalenyl diols can be considered as reaction intermediates. Yields of up to 99 % were obtained from 2‐methyl‐1‐naphthol as the starting material within 20 minutes. Probably for steric reasons, the diol is the final product obtained from 2‐ethyl‐1‐naphthol. For 4‐methoxy‐1‐naphthol the outcome is determined by the reaction temperature. At 25 °C the expected 1,1′‐dione is the major product, whereas at 60 °C 1′‐hydroxy‐4′‐methoxy‐2,2′‐binaphthalenyl‐1,4‐dione is formed; the loss of one methoxy unit and the preservation of the hydroxy group can be explained by the competitive cleavage of one of the two OMe bonds at higher temperature. Unpromoted platinum and a range of other metallic catalysts, including gold and Raney nickel, were also found to be active. The products obtained are brightly colored solids that could be used as dyes. The method described is truly catalytic and environmentally benign. The potential of the technique justifies further research to expand on the applicability of this novel method.

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Section: Resultssupporting

confidence: 93%

Oxidative Coupling of 1‐Naphthols over Noble and Base Metal Catalysts

2013

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“…We tested several conditions for the oxidation of 6‐methoxy‐2‐methylnaphthol to 6‐methoxymenadione (Table 1). The reaction did not proceed when performed with MnO 2 or Ag 2 O35 for 48 h. Oxidation by CAN, NBS ( N ‐bromosuccinimide),36 and CuCl 2 gave the desired menadione after 1–2 h in poor yields. Using Fremy's salt as the oxidizing reagent gave the 6‐methoxymenadione in quantitative yield when the reaction was performed on a small scale.…”

Section: Resultsmentioning

confidence: 99%

A Platform of Regioselective Methodologies to Access Polysubstituted 2‐Methyl‐1,4‐naphthoquinone Derivatives: Scope and Limitations

Rodo¹,

Feng²,

Jida³

et al. 2016

Eur J Org Chem

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A platform of synthetic methodologies has been established to access a focused library of polysubstituted 3‐benzylmenadione derivatives functionalized on the aromatic ring of the naphthoquinone core. Two main routes were explored: 1) The naphthol route, starting from either an α‐tetralone or a propiophenone, and 2) the regioselective Diels–Alder reaction, starting from various dienes and two 2‐bromo‐5(or 6)‐methyl‐1,4‐benzoquinones. 6‐Substituted 2‐methylnaphthols were synthesized by using a xanthate‐mediated free‐radical addition/cyclization sequence for the construction of the 6‐substituted menadione subunit. Furthermore, an efficient and simple new pathway that allows the formation of 6‐ or 7‐substituted 3‐(substituted‐benzyl)menadione regioisomers from a common commercial scaffold has also been developed by the naphthol route, advantageous with regard to step economy. Our synthetic methodologies exemplified by 34 compounds have allowed structure–activity relationships to be deduced for use as the basis for the development of new antimalarial redox‐active polysubstituted benzylmenadione derivatives.

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“…Ap art of the inner cavities within the supra-pyramid due to aggregation of AuNP might be occupied by anion.D uring the uptake process, the studied drugs were occupied in the remaining vacant cavities generated within the supra-pyramid.T herefore, this drug loading capacity within the supra-pyramid was effectively controlled by the nature of the anion.S upra-pyramids prepared in the presence of HNO 3 could not be used for drug delivery due to its strong oxidizing nature. [51] The colouro ft he solution drastically changed and resulted in white precipitate just after the addition of drugs to the supra-pyramids synthesized in the presence of HNO 3 .…”

Section: Resultsmentioning

confidence: 99%

“…Therefore, this drug loading capacity within the supra‐pyramid was effectively controlled by the nature of the anion. Supra‐pyramids prepared in the presence of HNO 3 could not be used for drug delivery due to its strong oxidizing nature [51] . The colour of the solution drastically changed and resulted in white precipitate just after the addition of drugs to the supra‐pyramids synthesized in the presence of HNO 3 .…”

Section: Resultsmentioning

confidence: 99%

Selective Release of Doxorubicin from Cucurbit[8]uril Stabilized Gold Supra‐Pyramid Host at pH of Small Intestine

Saini

Ghosh

Kumar

et al. 2020

Chemistry A European J

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Gold supra-pyramid structures wereo btained by the addition of acidic solution of cucurbit[8]uril(CB[8]) to an aqueous solution of citrate stabilized gold nanoparticles (AuNP). The reactionr esulted in the precipitation of suprapyramid from the solution after just 1min of shaking. Microscopic images confirmed formation of the supra-pyramid. The stepwise structural transformation towards the suprapyramid was examined with variable concentrations of CB[8] to AuNP solution. Anionic counterp arts of thesea cids (Br À , NO 3 À ,S O 4 2À and Cl À)c ontrolled the size of the synthesized supra-pyramids. These supra-pyramid hosts showed uptake of three anticancer drugs:o ral drugs etoposide, prednisolone and intravenousd rug doxorubicin. Releases of drugs from these hosts were emulated at acidic stomach pH, basic small intestinal pH and in the presence of human serum albumin (HSA). The specific release of doxorubicin was confirmed at small intestinal pH 7.4. Poor release of drugs in presence of CB[8] specific guest 1-adamantanamine confirmed the role of the supra-pyramid as the exclusive host. The release of doxorubicin from the supra-pyramid at pH 7.4 was confirmed by fluorescencem icroscopici maging with prostate cancer DU-145 cell line.

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A facile synthesis of naturally occurring binaphthoquinones: efficient oxidative dimerization of 4-alkoxy-1-naphthols using silver(II) oxide–40% nitric acid

Cited by 22 publications

References 20 publications

Oxidative Coupling of 1‐Naphthols over Noble and Base Metal Catalysts

Oxidative Coupling of 1‐Naphthols over Noble and Base Metal Catalysts

A Platform of Regioselective Methodologies to Access Polysubstituted 2‐Methyl‐1,4‐naphthoquinone Derivatives: Scope and Limitations

Selective Release of Doxorubicin from Cucurbit[8]uril Stabilized Gold Supra‐Pyramid Host at pH of Small Intestine

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