1137-42-4Relevant articles and documents
Application of Ionic Liquid Halide Nucleophilicity for the Cleavage of Ethers: A Green Protocol for the Regeneration of Phenols from Ethers
Boovanahalli, Shanthaveerappa K.,Kim, Dong Wook,Chi, Dae Yoon
, p. 3340 - 3344 (2004)
We have used the high nucleophilicity of bromide ion in the form of the ionic liquid, 1-n-butyl-3-methylimidazolium bromide ([bmim][Br]), for the nucleophilic displacement of an alkyl group to regenerate a phenol from the corresponding aryl alkyl ether. Using 2-methoxynaphthalene (1) as a model compound, we found that the combination of ionic liquid [bmim][Br] and p-toluenesulfonic acid with warming effected demethylation in 14 h, affording the desired product 2-naphthol (2) in good yield (97%). Various other protic acids (MsOH, hydrochloric acid (35%), dilute sulfuric acid (50%)) could be used as a proton source in this demethylation reaction. Under the same conditions, cleavage of alkyl alkyl ether 2-(3-methoxypropyl)naphthalene yielded mixture of corresponding 2-(3-bromopropyl)naphthalene and 2-(3-hydroxypropyl)naphthalene. Dealkylation of various aryl alkyl ethers could also be achieved using significantly reduced (i.e., stoichiometric) amounts of concentrated hydrobromic acid (47%) in the ionic liquid. Both procedures afforded the desired products in moderate to good yield; however, cleavage of aryl alkyl cyclic ether, 2,3-dihydrobenzofuran, resulted in low yield of the desired product o-2-bromoethylphenol. The convenience of this method for ether cleavage and its effectiveness using only a moderate excess of hydrobromic acid make it attractive as a green chemical method.
Modulation of reactivity of singlet radical pair in continuous flow: Photo-Fries rearrangement
Karjule, Neeta,Sharma, Mrityunjay K.,Nithyanandhan, Jayaraj,Kulkarni, Amol A.
, p. 316 - 321 (2018)
Photo-Fries rearrangement of phenyl benzoate is studied using continuous flow for modulating the reactivity of singlet radical pair by changing the viscosity of the solvent. The effect of flow and proximity of the reactants with the light source on the reactivity of radical pair, formed from singlet excited state was investigated in details. In non-viscous solvent, the results from flow synthesis were comparable to batch reactor. In viscous solvents, selectivity of ortho- and para-isomers (o-/p- isomer) of the product could be controlled by changing viscosity as well as the flow rate. Using flow synthesis, ortho- and para-isomer ratio was obtained as high as 8.45 which are twice as compared to batch experiment with in fraction of residence time.
Panel of New Thermostable CYP116B Self-Sufficient Cytochrome P450 Monooxygenases that Catalyze C?H Activation with a Diverse Substrate Scope
Tavanti, Michele,Porter, Joanne L.,Sabatini, Selina,Turner, Nicholas J.,Flitsch, Sabine L.
, p. 1042 - 1051 (2018)
The ability of cytochrome P450 monooxygenases to catalyse a wide variety of synthetically challenging C?H activation reactions makes them highly desirable biocatalysts both for the synthesis of chiral intermediates and for late-stage functionalisations. However, P450s are plagued by issues associated with poor expression, solubility and stability. Catalytically self-sufficient P450s, in which the haem and reductase domains are fused in a single protein, obviate the need for additional redox partners and are attractive as biocatalysts. Here we present a panel of natural self-sufficient P450s from thermophilic organisms (CYP116B65 from A. thermoflava, CYP116B64 from A. xiamenense, CYP116B63 from J. thermophila, CYP116B29 from T. bispora and CYP116B46 from T. thermophilus). These P450s display enhanced expression and stability over their mesophilic homologues. Activity profiling of these enzymes revealed that each P450 displayed a different fingerprint in terms of substrate range and reactivity that cover reactions as diverse as hydroxylation, demethylation, epoxidation and sulfoxidation. The productivity of the bio-transformation of diclofenac to produce the 5-hydroxy metabolite increased 42-fold using the thermostable P450-AX (>0.5 g L?1 h?1) compared to the P450-RhF system reported previously. In conclusion, we have generated a toolkit of thermostable self-sufficient P450 biocatalysts with a broad substrate range and reactivity.
-
Avnir et al.
, p. 1109 (1978)
-
Synthesis of 5-(4′-aroyl)-aryloxy methyl-4H-(1,2,4)-triazolin-3-thiol and their biological activity
Sudha,Shashikanth,Khanum, Shaukath Ara
, p. 85 - 88 (2004)
5-(4′-aroyl)-aryloxy methyl-4H-1,2, 4)-triazolin-3-thiols were synthesized by using substituted phenyl benzoates as the starting material. Phenyl benzoates on Fries rearrangement gave p-hydroxy benzophenones which on treatment with ethyl bromoacetate in presence of anhydrous potassium carbonate and dry acetone gave corresponding benzoyl phenyloxy esters in excellent yield. Esters were refluxed with thiosemicarbazide in presence of acetic anhydride gave cyclized title compounds. Supports for the structures of the synthesized compounds have been provided by their elemental analysis and spectral data. The newly synthesized compounds were screened for antibacterial and antifungal activities.
One-step reaction of friedel-crafts acylation and demethylation of aryl-methyl ethers catalyzed by ytterbium(III) triflate
Su, Weike,Jin, Can
, p. 4199 - 4205 (2004)
Catalytic amount of ytterbium(III) inflate [Yb(OTf)3] has been used to catalyze Friedel-Crafts acylation and demethylation of aryl-methyl ethers in one-step reaction to produce hydroxyacylphenones with moderate yields under mild conditions.
One-step hydroxylation of aryl and heteroaryl fluorides using mechanochemistry
Braje, Wilfried,Geneste, Hervé,Rodrigo, Eduardo,Walter, Magnus W.,Wiechert, Rainer
supporting information, p. 1469 - 1473 (2022/03/07)
Simple use of KOH allows the direct F to OH exchange of aromatic and heteroaromatic substrates under mechanochemical conditions. The reaction is performed in the absence of solvent with potassium hydroxide as OH source. As a result, this approach is both more atom economical and environmentally friendly than previously described methods for this transformation.
Discovery and characterization of a novel perylenephotoreductant for the activation of aryl halides
Guo, Baodang,Huang, Shuping,Li, Jia,Li, Min,Liu, Xuanzhong,Rao, Yijian,Wu, Yawen,Yin, Huimin,Yuan, Zhenbo,Zhang, Yan
, p. 111 - 120 (2021/06/16)
To develop a photocatalyst with catalytical activity for substrates with low reactivities is always highly desired. Herein, based on the principle of structure–property relationships, we rationally designed the natural product cercosporin, the naturally occurring perylenequinonoid pigment, to develop a novel organic perylenephotoreductant, hexacetyl reduced cercosporin (HARCP), through structural manipulation. Compared with cercosporin, HARCP shows prominent electrochemical and photophysical characteristics with greatly improved photoreductive activity, fluorescence lifetime and fluorescence quantum yield. These properties allowed HARCP as a powerful photoreductant to efficiently realize a series of benchmark reactions, including photoreduction, alkoxylation and hydroxylation to construct C–H and C–O bonds using aryl halides as substrates under mild conditions, all of which have never been achieved by the same photocatalyst. Thus, this study well supports the notion that the principle between structural manipulation and photocatalytic activity is of great significance to design customized photocatalysts for photoredox chemistry.
PhSe(O)OH/NHPI-catalyzed oxidative deoximation reaction using air as oxidant
Shi, Yaocheng,Wang, Feng,Yang, Chenggen,Yu, Lei
, (2021/09/06)
A novel oxidative deoximation method was developed in this article. Compared with the reported organoselenium-catalyzed oxidative deoximation reaction, this reaction employed N-hydroxyphthalimide (NHPI) as the co-catalyst, so that the oxidative deoximation reaction could utilize air as oxidant in the green DMC solvent under mild reaction conditions. Control experiments and X-ray photoelectron spectroscopy (XPS) analysis results indicated that NHPI was essential for activating the catalytic organoselenium species. It could accelerate the activation of molecular oxygen in air to promote the reaction process. The reaction can avoid metal residues in product and is of potential application values in pharmaceutical industry due to the transition metal-free process.
