2416-94-6Relevant articles and documents
Selective C-C and C-H Bond Activation/Cleavage of Pinene Derivatives: Synthesis of Enantiopure Cyclohexenone Scaffolds and Mechanistic Insights
Masarwa, Ahmad,Weber, Manuel,Sarpong, Richmond
, p. 6327 - 6334 (2015)
The continued development of transition-metal-mediated C-C bond activation/cleavage methods would provide even more opportunities to implement novel synthetic strategies. We have explored the Rh(I)-catalyzed C-C activation of cyclobutanols resident in hydroxylated derivatives of pinene, which proceed in a complementary manner to the C-C bond cleavage that we have observed with many traditional electrophilic reagents. Mechanistic and computational studies have provided insight into the role of C-H bond activation in the stereochemical outcome of the Rh-catalyzed C-C bond activation process. Using this new approach, functionalized cyclohexenones that form the cores of natural products, including the spiroindicumides and phomactin A, have been accessed.
Catalytic activity of a mordenite catalyst in alkylation of xylenols with methanol
Agaev,Madatzade
, p. 683 - 684 (2005)
The catalytic activity of a palladium-containing mordenite catalyst in alkylation of 2,6-, 2,4-, 2,5-, 2,3-, 3,4-, and 3,5-xylenols with methanol was studied. The main and by-products of catalysis and the activity of the catalyst in synthesis of individual trimethylphenols were determined.
OXIDATION OF PSEUDOCUMENE IN ACETIC ACID
Kholdeeva, O. A.,Kozhevnikov, I.V.,Sidel'nikov, V. N.,Utkin, V. A.
, (1989)
The oxidation of pseudocumene in the benzene nucleus can be effected in HOAc solutions by using inorganic oxidizing agents containing oxygen, such as NaNO3, heteropolyacids, O2, Na2S2O8, and H2O2, with Pd(OAc)2 as catalyst.Na2S2O8 and H2O2 are the most ef
Vapor phase methylation of m-Cresol over Ce-impregnated Cd1-xCrxFe2O4 (x = 0, 0.25, 0.50, 0.75 and 1.0) ferrospinels
Kadian, Malvika,Gupta
, p. 905 - 907 (2017)
Cd-Cr ferrospinels prepared by co-precipitation method were impregnated with cerium as promoter. Ce-impregnated ferrospinels were tested for the vapor phase alkylation of m-cresol with methanol. It has been observed that with increase in value of 'x' in C
Substrate substitution effects in the Fries rearrangement of aryl esters over zeolite catalysts
Bonrath, Werner,Létinois, Ulla,Lin, Ronghe,Medlock, Jonathan,Mitchell, Sharon,Netscher, Thomas,Pérez-Ramírez, Javier,Stemmler, René T.
, p. 4282 - 4292 (2020/07/30)
The catalytic transformation of aryl esters to hydroxyacetophenones via Fries rearrangement over solid acids is of interest to avoid the use of corrosive and toxic Lewis and Br?nsted acids traditionally applied. Microporous zeolites are known to catalyze the reaction of simple substrates such as phenyl acetate, but their application to substituted derivatives has received limited attention. To refine structure-activity relationships, here we examine the impact of various parameters including the solvent polarity, water content, acidic properties, and framework type on the reaction scheme in the Fries rearrangement of p-tolyl acetate over common solid acids. The results confirm the importance of providing a high concentration of accessible Br?nsted acid sites, with beta zeolites exhibiting the best performance. Extension of the substrate scope by substituting methyl groups in multiple positions identifies a framework-dependent effect on the rearrangement chemistry and highlights the potential for the transformation of dimethylphenyl acetates. Kinetic studies show that the major competitive path of cleavage of the ester C-O bond usually occurs in parallel to the Fries rearrangement. The possibility of sequentially acylating the resulting phenol depends on the substrate and reaction conditions.
Deoxyalkylation of guaiacol using haggite structured V4O6(OH)4
Yan, Fei,Wen, Zhe,Wu, Kai,Cui, Kai,Mai, Fuhang,Ma, Zewei,Sang, Yushuai,Bai, Yunfei,Chen, Hong,Li, Yongdan
, p. 1922 - 1932 (2019/04/29)
When V2O5 is used for the deoxygenation of guaiacol in methanol, it is reduced in situ to haggite structured V4O6(OH)4. Guaiacol prevents further reduction of the haggite phase in methanol and haggite catalyzes the partial deoxygenation of guaiacol. Haggite is a metastable redox catalyst for the deoxygenation of guaiacol, which follows the reverse Mars-van Krevelen mechanism. In addition, haggite is also a Lewis acid catalyst and catalyzes the alkylation of guaiacol with methanol as the alkylation reagent. The main products of the guaiacol deoxyalkylation are 2,6-dimethylphenol, 2-methoxy-6-methylphenol, 2,4,6-trimethylphenol, 2,3,6-trimethylphenol, 2,3,5,6-tetramethylphenol and 6-methyl-2-tert-butylphenol. Oligomerization takes place during the reaction but it is reversible. When the reaction is performed at 300 °C for 6 h, the 83.5% total selectivity for alkylphenols is achieved with a 99.0% conversion.
PROCESS FOR PREPARING (POLY)ALKYLATED PHENOLS
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Page/Page column 15; 16, (2018/06/12)
The present invention relates to the manufacturing and use of (poly)alkylphenols. They can be prepared from 2-(methoxymethyl)phenols by catalytic reduction in a high efficiency and selectivity.
Catalyst for synthesis of 2, 3, 6-trimethylphenol and preparation method thereof
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Paragraph 0017; 0018; 0019; 0020; 0023, (2018/09/11)
The invention discloses a catalyst for synthesis of 2, 3, 6-trimethylphenol and a preparation method thereof, and relates to a catalyst and a preparation method thereof. The catalyst for the synthesisof the 2,3,6-trimethylphenol from m-cresol comprises Fe2O3, SiO2 and CuO. In the preparation, Fe(NO3)3.9H2O is dissolved in deionized water, then Na2SiO3.9H2O and Cu(NO3)2.3H2O are added in sequence,and then dissolved to obtain a mixture A; ammonia water is added to the mixture A, stirred, aged, cooled to room temperature, and filtered by suction, and a filter cake is dried and calcined to obtain the catalyst for the synthesis of the 2,3,6-trimethylphenol from the m-cresol. The catalyst is free of precious metals and toxic heavy metals, low in cost, environmentally friendly, simple in preparation method, good in catalytic activity and high in selectivity, m-cresol conversion rate can reach 100%, and selectivity of the 2,3,6-trimethylphenol can reach 97.9%.
Construction of Acid–Base Synergetic Sites on Mg-bearing BEA Zeolites Triggers the Unexpected Low-Temperature Alkylation of Phenol
Xie, Jingyan,Zhuang, Wenxia,Zhang, Wei,Yan, Ning,Zhou, Yu,Wang, Jun
, p. 1076 - 1083 (2017/03/27)
Novel Mg-bearing BEA zeolites are synthesized to simultaneously endow significantly enhanced basicity without compromising acidity over the zeolite framework. Serving as efficient solid acid–base bifunctional catalysts, they achieve the liquid-phase selective methylation of phenol with methanol to produce o- and p-cresol (o/p=2) under mild conditions. The method is readily extendable to the alkylation of phenols with various alcohols. Stereo- and regioselectivity (>95 % for p-product) was attained on the alkylation of phenol with bulky tert-butyl alcohol, rendering the first acid–base cooperative shape-selective catalysis relying on the basicity of zeolites. A preliminary mechanistic analysis reveals that the remarkable activity and shape-selectivity come from the superior special acidic–basic synergetic catalytic sites on the uniform microporous channels of the BEA zeolite.
An Enzymatic Route to α-Tocopherol Synthons: Aromatic Hydroxylation of Pseudocumene and Mesitylene with P450 BM3
Dennig, Alexander,Weingartner, Alexandra Maria,Kardashliev, Tsvetan,Müller, Christina Andrea,Tassano, Erika,Schürmann, Martin,Ruff, Anna Jo?lle,Schwaneberg, Ulrich
, p. 17981 - 17991 (2017/11/29)
Aromatic hydroxylation of pseudocumene (1 a) and mesitylene (1 b) with P450 BM3 yields key phenolic building blocks for α-tocopherol synthesis. The P450 BM3 wild-type (WT) catalyzed selective aromatic hydroxylation of 1 b (94 %), whereas 1 a was hydroxylated to a large extent on benzylic positions (46–64 %). Site-saturation mutagenesis generated a new P450 BM3 mutant, herein named “variant M3” (R47S, Y51W, A330F, I401M), with significantly increased coupling efficiency (3- to 8-fold) and activity (75- to 230-fold) for the conversion of 1 a and 1 b. Additional π–π interactions introduced by mutation A330F improved not only productivity and coupling efficiency, but also selectivity toward aromatic hydroxylation of 1 a (61 to 75 %). Under continuous nicotinamide adenine dinucleotide phosphate recycling, the novel P450 BM3 variant M3 was able to produce the key tocopherol precursor trimethylhydroquinone (3 a; 35 % selectivity; 0.18 mg mL?1) directly from 1 a. In the case of 1 b, overoxidation leads to dearomatization and the formation of a valuable p-quinol synthon that can directly serve as an educt for the synthesis of 3 a. Detailed product pattern analysis, substrate docking, and mechanistic considerations support the hypothesis that 1 a binds in an inverted orientation in the active site of P450 BM3 WT, relative to P450 BM3 variant M3, to allow this change in chemoselectivity. This study provides an enzymatic route to key phenolic synthons for α-tocopherols and the first catalytic and mechanistic insights into direct aromatic hydroxylation and dearomatization of trimethylbenzenes with O2.
