- Switchable cascade C-H annulation to polycyclic pyryliums and pyridiniums: Discovering mitochondria-Targeting fluorescent probes
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Disclosed herein is a counterion additive-switched rhodium-catalyzed cascade triple C-H annulation of 4-hydroxy-1-naphthaldehydes with alkynes, in which six chemical bonds are formed in one-pot. This reaction enables the rapid assembly of diverse polycycl
- Chen, Xingyu,Yan, Lipeng,Liu, Yanhong,Yang, Yudong,You, Jingsong
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- Acetal elimination reaction accompanied with regioselective ring opening of 1,4-bisacetal-1,4-epoxy-1,4-dihydronaphthalenes
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– 1,4-Epoxy-1,4-dihydronaphthalenes are useful precursors to synthesize 1-naphthols by an acid-catalyzed ring opening of their 1,4-epoxy moieties. 1-Acetal-substituted 1,4-epoxy-1,4-dihydronaphthalene was also converted to 1-naphthol via the unique iron-catalyzed ring opening of the 1,4-epoxy moiety followed by the elimination of the acetal moiety. The present method could be applied to the regioselective syntheses of highly-functionalized 4-formyl-1-naphthols from the unsymmetrical 1,4-bisacetal-substituted 1,4-epoxy-1,4-dihydronaphthalenes.
- Sawama, Yoshinari,Kawajiri, Takahiro,Yamamoto, Yuta,Shishido, Yuko,Goto, Ryota,Sajiki, Hironao
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p. 126 - 133
(2019/06/24)
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- Phenolic Oxidation Using H2O2 via in Situ Generated para-Quinone Methides for the Preparation of para-Spiroepoxydienones
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Phenols are attractive starting materials for the preparation of highly substituted cyclohexane rings via dearomative processes. Herein we report an efficient preparation of dearomatized 1-oxaspiro[2.5]octa-4,7-dien-6-ones (para-spiroepoxydienones) via the nucleophilic epoxidation of in situ generated para-quinone methides from 4-(hydroxymethyl)phenols using aqueous H2O2. The developed protocol bypasses the need for stoichiometric bismuth reagents or diazomethane, which are frequently deployed for p-spiroepoxydienone preparation. The p-spiroepoxydienones are further elaborated in numerous downstream complexity-building transformations.
- McLaughlin, Michael F.,Massolo, Elisabetta,Cope, Thomas A.,Johnson, Jeffrey S.
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supporting information
p. 6504 - 6507
(2019/09/04)
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- Exploration of phenylpropanoic acids as agonists of the free fatty acid receptor 4 (FFA4): Identification of an orally efficacious FFA4 agonist
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The long chain free fatty acid receptor 4 (FFA4/GPR120) has recently been recognized as lipid sensor playing important roles in nutrient sensing and inflammation and thus holds potential as a therapeutic target for type 2 diabetes and metabolic syndrome. To explore the effects of stimulating this receptor in animal models of metabolic disease, we initiated work to identify agonists with appropriate pharmacokinetic properties to support progression into in vivo studies. Extensive SAR studies of a series of phenylpropanoic acids led to the identification of compound 29, a FFA4 agonist which lowers plasma glucose in two preclinical models of type 2 diabetes.
- Sparks, Steven M.,Aquino, Christopher,Banker, Pierette,Collins, Jon L.,Cowan, David,Diaz, Caroline,Dock, Steven T.,Hertzog, Donald L.,Liang, Xi,Swiger, Erin D.,Yuen, Josephine,Chen, Grace,Jayawickreme, Channa,Moncol, David,Nystrom, Christopher,Rash, Vincent,Rimele, Thomas,Roller, Shane,Ross, Sean
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p. 1278 - 1283
(2017/06/19)
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- Asymmetric dearomative spirolactonization of naphthols using λ3-iodanes under chiral phase-transfer catalysis
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The asymmetric phase-transfer catalytic effect of chiral Cinchona alkaloid-derived quaternary ammonium salts was investigated in the context of the λ3-iodane-mediated dearomative spirolactonization of naphthols. The scope and limitations of this methodology were evaluated using various substrates, which were converted into spirolactones in good yields and with enantiomeric excesses up to 58%.
- Antien, Kevin,Viault, Guillaume,Pouységu, Laurent,Peixoto, Philippe A.,Quideau, Stéphane
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supporting information
p. 3684 - 3690
(2017/06/13)
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- Role of substituents on the reactivity and product selectivity in reactions of naphthalene derivatives catalyzed by the orphan thermostable cytochrome P450, CYP175A1
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The thermostable nature of CYP175A1 enzyme is of potential interest for the biocatalysis at ambient temperature or at elevated temperature under environmentally benign conditions. Although little is known about the substrate selectivity of this enzyme, the biocatalytic activities of CYP175A1 on different substituted naphthalenes have been studied in oxidative pathway, and the effect of the substituent on the reaction has been determined. The enzyme first acts as a peroxygenase to convert these substituted naphthalenes to the corresponding naphthols, which subsequently undergo in-situ oxidative dimerization to form dyes of different colors possibly by the peroxidase-type activity of CYP175A1. The product analyses and kinetic measurements suggested that the presence of electron releasing substituent (ERS) in the substrate enhanced the substrate conversion, whereas the presence of electron withdrawing substituent (EWS) in the substrate drastically reduced the substrate conversion. The position of the ERS in the substrate was also found to play an important role in the transformation of the substrate. The results further demonstrate that mutation of the Leu80 residue to Phe enhances the reactivity of the enzyme by favoring the substrate association in the active site. The observed rates of the enzymatic oxygenation reaction of the substituted naphthalenes followed the Hammett correlation of substituent effect, supporting aromatic electrophilic substitution mechanism catalyzed by the cytochrome P450 enzyme.
- Banerjee, Shibdas,Goyal, Sandeep,Mazumdar, Shyamalava
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The aromatic hydroxyaldehydes 3a-3g, 5a-Sf, 8, 10 can be prepared by the action of BCl3, BBr3 or trifluoromethanesulfonic acid, on the aryl formates 1a-1f, 4a-e, 7, 9 via Fries rearrangement. BBr3 is more effective than BCl3. The activating ability of BBr3 can be improved by addition of FeCl3. Rearrangements which are induced by trifluoromethanesulfonic acid can give rise to the formations of regioisomers, which might be different from the products formed when the reaction is performed with Lewis acids. The yields of the aldehydes are lowered by subsequent condensation reactions. This view was confirmed by the isolation of a condensation product, which was characterized as a dibenzo[a,j]xanthene derivative 6 by crystal structure analysis. For the Fries rearrangement of formyl groups a new mechanism is proposed. 2-Hydroxy-1-naphthaldehyde 5c can be obtained in good yield from formic acid, BBr3, and 2-naphthol.
- Ziegler, Georg,Haug, Erwin,Frey, Wolfgang,Kantlehner, Willi
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p. 1178 - 1187
(2007/10/03)
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- Synthesis of duocarmycin SA by way of methyl 4-(Methoxycarbonyl)oxy-3H- pyrrolo[3,2-f]quinoline-2-carboxylate as a tricyclic heteroaromatic intermediate
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Formal syntheses of (±)-duocarmycin SA, natural (+)-duocarmycin SA and unnatural (-)-duocarmycin SA were accomplished by way of a tricyclic heteroaromatic compound 10b. For the preparation of 10, an N-oxide route aiming at a process 20 in Chart 3 was first investigated by synthesizing 19, derived from Stille coupling products 13 between bromopyrrole 7a and 3- (tributylstannyl)pyridines 12, but without success. As the second approach, Stille coupling products 9a-c were prepared by condensation between 7a and 2- substituted 3-(trialkylstannyl)pyridines 8a-f. Both 9b and 35, derived from 9c, were converted to their silyl enol ethers and then subjected to a palladium-catalyzed methyl ketone-arylation reaction in the presence of tributyltin fluoride and lithium chloride, affording 10a and 10b in excellent yields, especially from 35. Application to 10b of three successive operations, i.e., i) partial reduction of 10b to dihydropyridine derivatives 11a and 11b, ii) dihydroxylation of the double bonds formed to give 58 and 59, and iii) reductive elimination of the hydroxy groups adjacent to the nitrogen function and the aromatic ring, afforded 6 in fairly good yield. Compound 6 was readily converted to relay compounds 64 and 67, completing total syntheses of (±)-, (+)-, and (-)-duocarmycin SA. Both Sharpless asymmetric dihydroxylation (AD) and Jacobsen's asymmetric epoxidation were applied to 11a and 11b. At the best, 81% ee was observed in the AD reaction of 11a using 2,5-diphenyl-4,6-bis(9-O-dihydroquinyl)pyrimidine [(DHQ)2PYR], but the resulting 58 possessed an unnatural absolute configuration.
- Muratake, Hideaki,Tonegawa, Miyuki,Natsume, Mitsutaka
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p. 400 - 412
(2007/10/03)
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- SYNTHESIS AND CONFIGURATION OF SOME NEW BICYCLIC 3-ARYLIDENE- AND 3-HETEROARYLIDENE-2-OXINDOLES
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The synthesis of a novel class of bicyclic 3-arylidene- and 3-heteroarylidene-2-oxindoles possessing tyrosine kinase inhibitory activity is described.Compounds 1-16 have been prepared by condensation of 2-oxindole with a (hetero)aromatic aldehyde belonging to the naphthalene, tetralin, quinoline or indole series.The compounds so obtained were single E or Z isomers or separable mixtures thereof.The single E or Z isomers could be partially transformed into their isomers by acid or basic catalysis.The E/Z configuration assignment was achieved by 1H NMR spectroscopy on the basis of chemical shifts and NOE data obtained from NOESY spectra.
- Buzzetti, Franco,Pinciroli, Vittorio,Brasca, M. Gabriella,Crugnola, Angelo,Fustinoni, Silvia,Longo, Antonio
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- BENZENOID-QUINOID TAUTOMERISM OF AZOMETHINES AND THEIR STRUCTURAL ANALOGS BENZENOID-QUINOID TAUTOMERISM OF 4-HYDROXY-5,6-BENZOCINNAMALDEHYDE IMINES
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In the crystalline state and in solutions in nonpolar solvents 4-hydroxy-5,6-benzocinnamaldehyde has a benzenoid structure.In ethanol and DMSO tautomerism between the hydroxyaldehyde and p-hydroxymethylenequinone forms is observed.The N-aryl- and N-alkylimines of 4-hydroxy-5,6-benzocinnamaldehyde have the quinonoid structure in the crystalline state.In nonpolar solvents the n-arylimines axist in the form of the benzenoid tautomers, while a benzenoid-quinonoid equilibrium is observed for the N-alkylimines.In polar solvents the N-arylimines exhibit a tendency for quinonoidization.In these solvents the N-alkylimines exist preferentially in the form of the quinonoid structures.
- Andreeva, I. M.,Babeshko, O. M.,Bondarenko, E. M.,Medyantseva, E. A.,Minkin, V. I.
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p. 1864 - 1869
(2007/10/02)
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