2973-77-5Relevant articles and documents
Efficient and convenient synthesis of 3,4,5-trimethoxybenzaldehyde from p-cresol
Ji, Ya-Fei,Zong, Zhi-Min,Wei, Xian-Yong
, p. 2809 - 2814 (2002)
With p-cresol as starting material, 3,4,5-trimethoxybenzaldehyde was synthesized in an overall yield of 67.4% via bromination, hydrolysis, methoxylation and methylation.
Ni-NiO heterojunctions: a versatile nanocatalyst for regioselective halogenation and oxidative esterification of aromatics
Bhardwaj, Nivedita,Goel, Bharat,Indra, Arindam,Jain, Shreyans K.,Singh, Ajit Kumar,Tripathi, Nancy
, p. 14177 - 14183 (2021/08/16)
Herein, we report a facile method for the synthesis of Ni-NiO heterojunction nanoparticles, which we utilized for the nuclear halogenation reaction of phenol and substituted phenols usingN-bromosuccinimide (NBS). A remarkablepara-selectivity was achieved for the halogenated products under semi-aqueous conditions. Interestingly, blocking of thepara-position of phenol offeredortho-selective halogenation. In addition, the Ni-NiO nanoparticles catalyzed the oxidative esterification of carbonyl compounds with alcohol, diol or dithiol in the presence of a catalytic amount of NBS. It was observed that the aromatic carbonyls substituted with an electron-donating group favoured nuclear halogenation, whereas an electron-withdrawing group substitution in carbonyl compounds facilitated the oxidation reaction. In addition, the catalyst was magnetically separated and recycled 10 times. The tuned electronic structure at the Ni-NiO heterojunction controlled selectivity and activity as no suchpara-selectivity was observed with commercially available NiO or Ni nanoparticles.
Magnetic nano-structured cobalt-cobalt oxide/nitrogen-doped carbon material as an efficient catalyst for aerobic oxidation of p-cresols
Liang, Cheng,Li, Xuefeng,Su, Diefeng,Ma, Qiyi,Mao, Jianyong,Chen, Zhirong,Wang, Yong,Yao, Jia,Li, Haoran
, p. 121 - 131 (2018/05/22)
Efficient aerobic oxidation has been developed for the selective preparation of a sequence of valuable p-hydroxybenzaldehydes from corresponding p-cresols, using a new magnetically separable catalyst of nano-structured cobalt-cobalt oxide/nitrogen-doped carbon (CoOx@CN) material. CoOx@CN showed high activity for the 2-methoxy-4-cresol oxidation to vanillin, giving great yield (90%) and with good turnover number (210), as well as other p-cresols in good to great yields. The catalytic performance was investigated and related to the structural, chemical and magnetic properties which determined by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Fourier-transform infrared spectroscopy (FT-IR) and vibrating sample magnetometer (VSM). The effects of base to substrate molar ratio, catalyst concentration, temperature, and solvent on the conversion and selectivity patterns also have been studied. The investigation revealed that remarkable catalytic properties of CoOx@CN could be ascribed to the active species cobalt oxide, doped nitrogen and porous carbon with large surface area. The size of the catalyst is a key factor for catalyst performance. The ferromagnetic property of catalyst enables to recycle easily by an external magnetic field and reuse six successive times without significant activity loss.
Graphene Oxide Promoted Oxidative Bromination of Anilines and Phenols in Water
Ghorpade, Prashant Vasantrao,Pethsangave, Dattatray Appasha,Some, Surajit,Shankarling, Ganapati Subray
, p. 7388 - 7397 (2018/07/29)
The mildly acidic and oxidative nature of graphene oxide, with its large surface area available for catalytic activity, has been explored in aromatic nuclear bromination chemistry for the first time. The versatile catalytic activity of graphene oxide (GO) has been used to selectively and rapidly brominate anilines and phenols in water. The best results were obtained at ambient temperatures using molecular bromine in a protocol promoted by oxidative bromination catalyzed by GO; these transformations proceeded with 100% atom economy with respect to bromine and high selectivities for the tribromoanilines and -phenols. Reduced graphene oxide (r-GO) was observed to form after the second recycle (third use) of GO. This technique is also effective with N-bromosuccinimide (NBS) as the brominating reagent. In the case of NBS, reactions were instantaneous and the GO displayed excellent recyclability without any loss of activity over several cycles.
A short and efficient total synthesis of the bromotyrosine-derived alkaloid psammaplysene A
Xu, Jingjing,Wang, Kai,Wu, Jinlong
, p. 13747 - 13749 (2018/04/25)
Psammaplysene A, an inhibitor of FOXO1a-mediated nuclear export, has been synthesized by a concise and improved route from tyrosine-derived acid and amine fragments which were easily constructed using commercially available p-hydroxybenzaldehyde and tyramine as starting material, respectively. The strategy provides an efficient access of psammaplysene analogues that can be explored for potential pharmaceutical or biological activities.
A trimethoprim intermediate 3, 5 - dibromo - 4 - hydroxybenzaldehyde preparation
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Paragraph 0020; 0021; 0022; 0023; 0024; 0025-0028, (2017/08/25)
The invention provides a preparation method of trimethoprim midbody 3,5-dibromo-4-hydroxy benzaldehyde. The preparation method comprises the following steps of sequentially adding paracresol, ethanoic acid and zinc chloride in a reaction container; uniformly stirring; slowly adding benzyl trimethyl ammonium tribromide after cooling to the temperature of 0 DEG C; reacting for 1-2 hours at the temperature of 10-15 DEG C; heating to the temperature of 90-95 DEG C and reacting for 1.5-3 hours; performing reduced pressure distillation on reaction liquid to recycle acetic acid; adding water in a substrate, stirring, heating and performing backflow hydrolysis for 2-4 hours; cooling to room temperature; and filtering, washing and drying to obtain the 3,5-dibromo-4-hydroxy benzaldehyde. Reaction conditions of the preparation method are gentle, a technology is simple, reaction speed is high, the purity of products is above 98%, yield is above 93%, and BTMABr3 serves as a bromination reagent and replaces bromine with high toxicity. The preparation method has the advantages of safety, zero toxicity and environmental protection.
Concise total synthesis of aplysinellamides A and B
Gan, Haifeng,Huang, Yu,Feng, Weiyang,Zhu, Wentong,Guo, Kai
, p. 336 - 339 (2015/08/11)
Concise and efficient total syntheses of bromotyrosine-derived metabolites aplysinellamides A and B, isolated from Australian marine sponge Aplysinella sp., have been accomplished in seven steps. A condensation between cinnamic acid and Boc-D-lysine methyl ester was applied to form the amide skeleton as a key step.
Synthesis and Solvatochromism of Substituted 4-(Nitrostyryl)phenolate Dyes
Stock, Rafaela I.,Nandi, Leandro G.,Nicoleti, Celso R.,Schramm, Adriana D. S.,Meller, Sheila L.,Heying, Renata S.,Coimbra, Daniel F.,Andriani, Karla F.,Caramori, Giovanni F.,Bortoluzzi, Adailton J.,Machado, Vanderlei G.
, p. 7971 - 7983 (2015/09/01)
4-(Nitrostyryl)phenols 2a-9a were synthesized, and by deprotonation in solution, the solvatochromic phenolates 2b-9b were formed. Their absorption bands in the vis region of the spectra are due to π- π? electronic transitions, of an intramolecular charge-transfer nature, from the electron-donor phenolate toward the electron-acceptor nitroarene moiety. The frontier molecular orbitals and natural bond orbitals were analyzed for the protonated and deprotonated forms. The calculated geometries are in agreement with X-ray structures observed for 4a, 6a, and 8a. The HOMO-LUMO energy gaps suggest that, after their deprotonation, an increase in the electron delocalization is observed. In the protonated compounds, the HOMO is primarily localized over the phenol ring and the C=C bridge. After deprotonation, it extends toward the entire molecule, including the NO2 groups. The solvatochromism of each dye was studied in 28 organic solvents, and it was found that all compounds exhibit a reversal in solvatochromism, which is interpreted in terms of the ability of the media to stabilize their electronic ground and excited states to different extents. The Catalán multiparameter equation is used in the interpretation of the solvatochromic data, revealing that the most important contribution to the solute/solvent interaction is the hydrogen-bond donor acidity of the solvent.
Synthesis and antibacterial activities of cadiolides A, B and C and analogues
Boulangé, Agathe,Parraga, Javier,Galán, Abraham,Cabedo, Nuria,Leleu, Stéphane,Sanz, Maria Jesus,Cortes, Diego,Franck, Xavier
, p. 3618 - 3628 (2015/07/27)
The one-pot multicomponent synthesis of natural butenolides named cadiolides A, B, C and analogues has been realized. The antibacterial structure activity relationship shows that the presence of phenolic hydroxyl groups and the number and position of bromine atoms on the different aromatic rings are important features for antibacterial activity, besides it was demonstrated the tolerance of both benzene and furan ring at position 3 of the butenolide nucleus. Furthermore, none of the most relevant antibacterial compounds showed any cytotoxicity in freshly isolated human neutrophils.
Efficient Co(OAc)2-catalyzed aerobic oxidation of EWG-substituted 4-cresols to access 4-hydroxybenzaldehydes
Jiang, Jian-An,Du, Jia-Lei,Liao, Dao-Hua,Wang, Zhan-Guo,Ji, Ya-Fei
supporting information, p. 1406 - 1411 (2014/03/21)
We reported an efficient ligand-free Co(OAc)2·4H 2O/NaOH/O2/ethylene glycol reaction system that enables selective aerobic oxidation of a wide range of substrates covering 2,6-di-EWG-, 2,3,6-tri-EWG-, 2-EWG-, and 2-EWG-6-EDG-substituted 4-cresols into the corresponding 4-hydroxybenzaldehydes. Based on the experimental investigations and well-defined p-benzoquinone methides, a plausible reaction mechanism was proposed. Considering the simplicity of the procedure and importance of the products, the methodology was expected to become a favorable and practical tool in related benzylic C(sp3)-H functionalization chemistry.
