- Dearomatization-Rearomatization Strategy for ortho-Selective Alkylation of Phenols with Primary Alcohols
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Phenols are common precursors and core structures of a variety of industrial chemicals ranging from pharmaceuticals to polymers. However, the synthesis of site-specifically substituted phenols is challenging, and thus the development of new methods for this purpose would be highly desirable. Reported here is a protocol for palladium-catalyzed ortho-selective alkylation reactions of phenols with primary alcohols by a dearomatization-rearomatization strategy, with water as the sole by-product. Various substituted phenols and primary alcohols were compatible with the standard reaction conditions. The detailed mechanism of this transformation was also investigated.
- Yu, Jianjin,Li, Chao-Jun,Zeng, Huiying
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supporting information
p. 4043 - 4048
(2020/12/18)
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- Palladium-catalyzed aerobic synthesis of: Ortho -substituted phenols from cyclohexanones and primary alcohols
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Due to the importance of phenols as structural cores and precursors of chemical products, synthesis of site-specific substituted phenols is highly desirable and a significant challenge. An aerobic palladium-catalyzed site-specific synthesis of ortho-substituted phenols from cyclohexanones and primary alcohols via an oxidation/aldol/dehydration/aromatization process has been developed. Various substituted cyclohexanones and primary alcohols are successfully transformed into ortho-substituted phenols. In addition, this catalytic reaction uses air as the terminal oxidant and generates water as the sole by-product. Furthermore, the method can also be extended to polyhydroxyl substituted substrates with high chemoselectivity between primary and secondary alcohols. This method provides a greener tool for synthesizing primary alkyl ortho-substituted phenols.
- Zeng, Huiying,Yu, Jianjin,Li, Chao-Jun
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supporting information
p. 1239 - 1242
(2020/02/04)
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- THIOSEMICARBAZONES INHIBITORS OF LYSOPHOSPHATIDIC ACID ACYLTRANSFERASE AND USES THEREOF
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Lysophosphatidic acid acyltransferase-beta (LPAAT-β) catalyzes the production of phosphatidic acid (PA) from lysophosphatidic acid (LPA). The lipid cofactor PA contributes to the activation of c-Raf, BRAF, mTOR and PKC-ζ. LPAAT-β expression is a prognostic factor in gynecologic malignancies and is being investigated as a therapeutic target in a variety of tumor types. A class of thiosemicarbazones was identified as inhibitors of LPAAT-β from a screen of a library of small molecules. A focused library of thiosemicarbazones derivatives was prepared and led to the development of compounds which potently inhibit LPAAT-β and inhibit the growth of MiaPaCa2 human pancreatic cancer cells.
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Page/Page column 16
(2015/11/17)
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- 4,4′-Unsymmetrically substituted 3,3′-biphenyl alpha helical proteomimetics as potential coactivator binding inhibitors
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A series of unsymmetrically substituted biphenyl compounds was designed as alpha helical proteomimetics with the aim of inhibiting the binding of coactivator proteins to the nuclear hormone receptor coactivator binding domain. These compounds were synthes
- Weiser, Patrick T.,Chang, Ching-Yi,McDonnell, Donald P.,Hanson, Robert N.
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p. 917 - 926
(2014/01/23)
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- A 'meta effect' in the fragmentation reactions of ionised alkyl phenols and alkyl anisoles
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The competition between benzylic cleavage (simple bond fission [SBF]) and retro-ene rearrangement (RER) from ionised ortho, meta and para RC 6H4OH and RC6H4OCH3 (R = n-C3H7, n-C4H9, n-C5H11, n-C7H15, n-C9H19, n-C 15H31) is examined. It is observed that the SBF/RER ratio is significantly influenced by the position of the substituent on the aromatic ring. As a rule, phenols and anisoles substituted by an alkyl group in meta position lead to more abundant methylene-2,4-cyclohexadiene cations (RER fragmentation) than their ortho and para homologues. This 'meta effect' is explained on the basis of energetic and kinetic of the two reaction channels. Quantum chemistry computations have been used to provide estimate of the thermochemistry associated with these two fragmentation routes. G3B3 calculation shows that a hydroxy or a methoxy group in the meta position destabilises the SBF and stabilises the RER product ions. Modelling of the SBF/RER intensities ratio has been performed assuming two single reaction rates for both fragmentation processes and computing them within the statistical RRKM formalism in the case of ortho, meta and para butyl phenols. It is clearly demonstrated that, combining thermochemistry and kinetics, the inequality (SBF/RER) metaorthopara holds for the butyl phenols series. It is expected that the 'meta effect' described in this study enables unequivocal identification of meta isomers from ortho and para isomers not only of alkyl phenols and alkyl anisoles but also in other alkyl benzene series. Copyright
- Bouchoux, Guy,Sablier, Michel,Miyakoshi, Tetsuo,Honda, Takashi
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p. 539 - 546
(2012/09/22)
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- Metal cation-exchanged montmorillonite (Mn+-mont)-catalysed aromatic alkylation with aldehydes and ketones
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The alkylation of aromatic compounds with aldehydes and ketones in the presence of a variety of metal cation-exchanged montmorillonites (Mn+-mont; Mn+ = Zr4+, Al3+, Fe3+, Zn2+, H+, Na+) has been investigated. Al3+- and Zr4+-Monts are revealed to be effective as catalysts, while no reaction takes place with Na+-mont. Al3+-Mont-catalysed alkylation of phenol with several aldehydes produces mainly or almost solely the corresponding gem-bis(hydroxyphenyl)alkanes (bisphenols) in good yields, while that with several ketones affords selectively the corresponding alkylphenols in moderate to good yields. The alkylation always occurs at the carbonyl carbon without any skeletal rearrangement and the kind of products depends much on the steric hindrance of an electrophilic intermediary carbocation. The alkylation of anisole, veratrole and p-cresol proceeds well, while that of toluene, benzene, chlorobenzene and nitrobenzene scarcely occurs.
- Tateiwa, Jun-Ichi,Hayama, Ei,Nishimura, Takahiro,Uemura, Sakae
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p. 1923 - 1928
(2007/10/03)
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- Preparation of diphenolics
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A process for the production of diphenolic compounds having a divalent bridge. A first disubstituted phenol is reacted with an aldehyde in the presence of a secondary amine and excess alcohol to form an ether intermediate. The ether intermediate is reacted with a phenol having an open ortho or para position to form a diphenolic.
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- Preparation of phenolic ethers
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Phenolic ethers are produced by reacting a phenol with a compound selected from an alkyl halide, an aryl halide, a dialkyl sulphate and a diaryl sulphate in the presence as catalyst of an amidine.
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