1888-41-1Relevant academic research and scientific papers
Switchable cascade C-H annulation to polycyclic pyryliums and pyridiniums: Discovering mitochondria-Targeting fluorescent probes
Chen, Xingyu,Yan, Lipeng,Liu, Yanhong,Yang, Yudong,You, Jingsong
, p. 15080 - 15083 (2020/12/22)
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
Efficient cross-coupling of aryl/alkenyl triflates with acyclic secondary alkylboronic acids
Si, Tengda,Li, Bowen,Xiong, Wenrui,Xu, Bin,Tang, Wenjun
, p. 9903 - 9909 (2017/12/12)
Aryl-secondary alkyl cross-coupling with aryl sulfonate esters as coupling partners remains a significant challenge. Efficient cross-coupling between aryl/alkenyl triflates and acyclic secondary alkylboronic acids is realized for the first time to provide a series of sterically congested acyclic secondary alkyl arenes/olefins in good to excellent yields. The employment of sterically bulky P,PO ligand L1/L2 is crucial for the high yields and selectivities. The method has enabled a concise and 4-step synthesis of a key intermediate of male contraceptive agent and PAF antagonist gossypol.
Asymmetric Alkynylation of β-Ketoesters and Naphthols Promoted by New Chiral Biphenylic Iodanes
Companys, Simon,Peixoto, Philippe A.,Bosset, Cyril,Chassaing, Stefan,Miqueu, Karinne,Sotiropoulos, Jean-Marc,Pouységu, Laurent,Quideau, Stéphane
, p. 13309 - 13313 (2017/10/05)
The preparation of new chiral biphenylic λ3-iodane reagents bearing transferable alkynyl ligands is described. These reagents transfer their carbon-based ligands onto β-ketoesters with an enantiomeric excess (ee) up to 68 %, and most remarkably, enable the dearomative alkynylation of naphthols in good to high yields up to 84 % ee.
Synthesis of 1,2-naphthalenediol derivatives by Rh-catalyzed intermolecular O[sbnd]H insertion reaction of 1,2-diazonaphthoquinones with water and alcohols
Kitamura, Mitsuru,Otsuka, Kota,Takahashi, Shuhei,Okauchi, Tatsuo
supporting information, p. 3508 - 3511 (2017/10/06)
Rh(II)-catalyzed O[sbnd]H insertion reaction of diazonaphthoquinones with water or alocohols proceeded to yield 1,2-naphthalenediol derivatives.
Photo-Wolff rearrangement of 2-Diazo-1,2-naphthoquinone: Stern-Volmer analysis of the stepwise reaction pathway
Ladinig, Manfred,Ramseier, Markus,Wirz, Jakob
, p. 678 - 683 (2015/05/13)
Abstract 2-Diazo-1,2-naphthoquinone (1) and its derivatives are the photoactive components in Novolak photoresists. A femtosecond infrared study has established that the photoreaction of 1 proceeds largely by a concerted Wolff rearrangement yielding the ketene 1H-inden-1-ylidene-methanone (3) within 300 fs after excitation, but earlier trapping studies gave evidence for a minor reaction path via a carbene intermediate 1-oxo-2(1H)-naphthalenylidene (2) with a lifetime of about 10 ps. Here, we provide a quantitative assessment of the stepwise pathway by Stern-Volmer analysis of the trapping of 2 by methanol to yield 2-methoxy-1-naphthol (4). We conclude that the lifetime of the carbene 2 is at least 200 ps. Moreover, [3 + 2]cycloaddition of 2 and acetonitrile yielding 2-methylnaphth[2,1-d]oxazole (5) was observed. A comparison of the yields of 5 formed upon photolysis and upon thermolysis of 1 in acetonitrile provides evidence that a substantial part of the hot nascent carbene 2 formed photolytically rearranges to the ketene 3 during its vibrational relaxation (hot ground-state reaction). A quantitative assessment of the stepwise versus concerted photodeazotization pathways of 2-diazo-1,2-naphthoquinone (1) forming ketene 3 is provided. Trapping of the carbene intermediate 2 by methanol yields 2-methoxy-1-naphthol (4) in up to 12% yield. [3+2]Cycloaddition of 2 and acetonitrile yielding 2-methylnaphth[2,1-d]oxazole (5) was also observed. The lifetime of the thermalized carbene 2 is at least 200 ps. A comparison of the yields of 5 formed upon photolysis and upon thermolysis of 1 in acetonitrile provides evidence that a substantial part of the hot nascent carbene 2 formed photolytically rearranges to the ketene 3 during its vibrational relaxation (hot ground-state reaction).
Acceleration of the Dakin reaction by trifluoroacetic acid
Natu, Arun D.,Burde, Ameya S.,Limaye, Rohan A.,Paradkar, Madhusudan V.
, p. 381 - 382 (2014/07/08)
An acceleration of the Dakin reaction caused by addition of trifluoroacetic acid is described. The modified protocol converts aromatic aldehydes to the corresponding phenols within 4 hours at room temperature by means of hydrogen peroxide in acidic medium. This acceleration is attributed to the stability of hydrogen peroxide in an acidic medium. This modified protocol provides alternative and easy access to important phenolic precursors that have been used in the synthesis of various natural products.
Substituent-induced regioselective hydroxylation of the aromatic C-H bond on naphthalene with metachloroperbenzoic acid catalyzed by F20TPPMnCl
Chen, Chang-Di,Sheng, Wen-Bing,Shi, Guo-Jun,Guo, Can-Cheng
, p. 23 - 29 (2013/03/13)
The regioselective hydroxylation of the aromatic C-H bond on a series of naphthalenes with different β-substituent R (R = H, Me, Et, i-Pr, OMe, COOH, Br, etc.) was studied, and the substituent effect on the regioselectivity was investigated. The electron-donating substituent afforded the aromatic C-H bond hydroxylation at the 1α position with more than 80% selectivity, while the electron-withdrawing substituent afforded the aromatic C-H bond hydroxylation at the 4α position with more than 60% selectivity of β-substituted naphthalene hydroxylated with metachloroperbenzoic acid catalyzed by tetrakis(pentafluorophenyl)porphyrin manganese(III) chloride. The research showed that the steric and electronic effects of the substituent appeared to play a significant role in determining the regioselectivity, and the electronic effect was of more importance than the steric effect of the substituent in the current situation. The studies may provide additional proofs for the stepwise mechanism of the aromatic C-H bond hydroxylation through a cationic intermediate. Copyright
Structure-affinity studies for a novel series of homochiral naphtho and tetrahydronaphtho analogues of α1 antagonist WB-4101
Bolchi, Cristiano,Catalano, Paolo,Fumagalli, Laura,Gobbi, Marco,Pallavicini, Marco,Pedretti, Alessandro,Villa, Luigi,Vistoli, Giulio,Valoti, Ermanno
, p. 4937 - 4951 (2007/10/03)
A number of enantiomeric pairs of naphthodioxane, tetrahydronaphthodioxane and naphthoxy analogues of WB-4101 (1) were designed and synthesized in order to improve the selectivity profile of the parent compound, hopefully in favour of the α1a-AR with respect to the other two α1 subtypes and the 5-HT1A receptor. The new compounds 2-8 and, in addition, the two enantiomers of 1 were tested in binding assays on the α1a-AR, α1b-AR, α1d-AR, and the 5-HT1A receptor. Two of them, namely the naphtho- and tetrahydronaphthodioxane derivatives (S)-2 and (S)-3, showed lower, but significantly more specific α1a affinity than (S)-1, while the two enantiomers of the 2-methoxy-1-naphthoxy analogue 6 maintained most of the very high α1a affinity of (S)-1 and its α1a versus α1b selectivity slightly increasing the α1a/α1d and α1a/5HT 1A affinity ratios. The SAR data were evaluated in the light of known α1 subtype pharmacophores and of the α1a-AR binding mode of WB-4101 resultant from literature mutagenesis studies disclosing some interesting consonances with these models.
Selective cyclic peptides with melanocortin-4 receptor (MC4-R) agonist activity
-
, (2008/06/13)
Peptides cyclized via disulfide or lactam bridges having melanocortin-4 receptor (MC4-R) agonist activity useful for treatment of obesity.
2-Alkoxyarenol-derived orthoquinols in carbon-oxygen, carbon-nitrogen and carbon-carbon bond-forming reactions
Quideau, Stéphane,Pouységu, Laurent,Oxoby, Mayalen,Looney, Matthew A
, p. 319 - 329 (2007/10/03)
Silylated oxygen- and nitrogen-tethered orthoquinol acetates, generated by phenyliodine(III) diacetoxy-mediated oxidative acetoxylation of 2-alkoxyphenols in CH2Cl2 can be used to furnish regioselectively benzannulated heterocycles. Oxidative activation of 2-alkoxynaphthols with non-nucleophilic phenyliodine(III) bis(trifluoroacetoxy) in the presence of carbon nucleophiles, including oxidation sensitive silyl enol ethers, constitute a potentially valuable route to naturally occurring vicinally oxygenated benz[a]anthracene motifs.
