93-96-9Relevant academic research and scientific papers
Gold(i)-catalysed dehydrative formation of ethers from benzylic alcohols and phenols
Veenboer, Richard M. P.,Nolan, Steven P.
, p. 3819 - 3825 (2015)
We report the cross-dehydrative reaction of two alcohols to form unsymmetrical ethers using NHC-gold(i) complexes (NHC = N-heterocyclic carbene). Our progress in developing this reaction into a straightforward procedure is discussed in detail. The optimised methodology proceeds under mild reaction conditions and produces water as the sole by-product. The synthetic utility of this environmentally benign methodology is exemplified by the formation of a range of new ethers from readily available phenols bearing electron withdrawing substituents and secondary benzylic alcohols with various substituents. Finally, we present experimental results to account for the chemoselectivity obtained in these reactions.
Dioxygen oxidation of 1-phenylethanol with gold nanoparticles and N-hydroxyphthalimide in ionic liquid
Hosseini-Monfared, Hassan,Meyer, Hajo,Janiak, Christoph
, p. 72 - 78 (2013)
Gold nanoparticles (Au-NPs) of 8 nm average diameter were obtained by thermal reduction under nitrogen from KAuCl4 in the presence of n-butylimidazol dispersed in the ionic liquid (IL) 1-n-butyl-3-methylimidazolium tetrafluoroborate (BMIm+BF4-). Characterization of the Au-NP was done by transmission electron microscopy (TEM) and dynamic light scattering (DLS). Catalytic activities of the Au-NP/IL dispersion were evaluated in the oxidation of 1-phenylethanol at 100 and 160 °C under 4 bar pressure of dioxygen in a base-free system. Au-NP in combination with the radical initiator N-hydroxyphthalimide (NHPI) showed good conversion and selectivity for the oxidation of 1-phenylethanol to acetophenone through formation of an α-hydroxy carbon radical. The concomitant side products di(1-phenylethyl)ether and di(1-phenylethyl)peroxide were rationalized by an equilibrium due to the IL matrix of the α-hydroxy carbon radical with the 1-phenylethoxy radical. Maximum turnover number was ～5200 based on the total number of moles of gold but a factor of about six larger, TON ≈ 31 300, when only considering the Au-NP surface atoms. The fraction (N S/NT) of exposed surface atoms (NS ≈ 2560) for an average 8 nm Au-NP (having NT ≈ 15 800 atoms in a ～17-shell icosahedral or cuboctahedral particle) was estimated here as 0.16.
An expedient, efficient and solvent-free synthesis of T3P-mediated amidation of benzhydrols with poorly reactive N-nucleophiles under MW irradiation
Cheruku, Srinivas,Manikyanally, Kumara N.,Mantelingu, Kempegowda,Nagarakere, Sandhya C.,Narayana, Yatheesh,Rangappa, Kanchugarakoppal S.,Sunilkumar, Makanahalli P.
, p. 4421 - 4426 (2022/03/14)
An expedient, efficient, economical, environmentally benign, and solvent free amidation protocol of benzhydrols with less reactive nitrogen nucleophiles assisted by propylphosphonic anhydride (T3P) under microwave irradiation has been developed. The methodology has been deployed for a wide range of heterocycles and electron-withdrawing & electron-donating groups. The protocol resulted in good to excellent yields under the given conditions (26 examples, 68-93% yield).
Iodine catalysed synthesis of unsymmetrical benzylic ethers by direct cross-coupling of alcohols
Kharrngi, Balamphrang,Basumatary, Grace,Bez, Ghanashyam
, (2021/09/13)
Although symmetrical ethers can be synthesized easily from alcohols, synthesis of unsymmetrical ethers by dehydrative cross-coupling of alcohols is still a challenge. While dehydrative cross-coupling is environmentally appealing due to formation of water as the only byproduct, the chances for formation of symmetrical ethers always exist. The existing transition metal based methods give good selectivity, but the catalyst are costly and not readily available. Here, we present a simple, readily available, and cost-effective catalyst in the form of molecular iodine which catalyzes a highly selective cross-coupling of benzylic alcohols with benzyl, alkyl, and aryl alcohols to give their corresponding unsymmetrical ethers in good to excellent yield.
Synthetic method of borane-catalyzed symmetric ether
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Paragraph 0033-0042, (2021/07/28)
The invention provides a borane-catalyzed symmetric ether synthesis method, which is characterized in that alcohol is used as a raw material, and under the catalysis of B(2,6-Cl2C6H3) (p-HC6F4) 2, etherification reaction is carried out through intermolecular dehydration to generate ether. The reaction process is simple, mild, pollution-free and efficient.
Cascade Reductive Friedel-Crafts Alkylation Catalyzed by Robust Iridium(III) Hydride Complexes Containing a Protic Triazolylidene Ligand
Albrecht, Martin,Alshakova, Iryna D.
, p. 8999 - 9007 (2021/07/31)
The synthesis of complex molecules like active pharmaceutical ingredients typically requires multiple single-step reactions, in series or in a modular fashion, with laborious purification and potentially unstable intermediates. Cascade processes offer attractive synthetic remediation as they reduce time, energy, and waste associated with multistep syntheses. For example, triarylmethanes are traditionally prepared via several synthetic steps, and only a handful of cascade routes are known with limitations due to high catalyst loadings. Here, we present an expedient catalytic cascade process to produce triarylmethanes. For this purpose, we have developed a bifunctional iridium system as the efficient catalyst to build heterotriaryl synthons via reductive Friedel-Crafts alkylation from ketones, arenes, and hydrogen. The catalytically active species were generated in situ from a robust triazolyl iridium(III) hydride complex and acid and is composed of a metal-bound hydride and a proximal ligand-bound proton for reversible dihydrogen release. These complexes catalyze the direct hydrogenation of ketones at slow rates followed by dehydration. Appropriate adjustment of the conditions successfully intercepts this dehydration and leads instead to efficient C-C coupling and Friedel-Crafts alkylation. The scope of this cascade process includes a variety of carbonyl substrates such as aldehydes, (alkyl)(aryl)ketones, and diaryl ketones as precursor electrophiles with arenes and heteroarenes for Friedel-Crafts coupling. The reported method has been validated in a swift one-step synthesis of the core structure of a potent antibacterial agent. Excellent yields and exquisite selectivities were achieved for this cascade process with unprecedentedly low iridium loadings (0.02 mol %). Moreover, the catalytic activity of the protic system is significantly higher than that of an N-methylated analogue, confirming the benefit of the Ir-H/N-H hydride-proton system for high catalytic performance.
Direct Nucleophilic Substitution of Alcohols Using an Immobilized Oxovanadium Catalyst
Nishio, Tomoya,Yoshioka, Shin,Hasegawa, Kai,Yahata, Kenzo,Kanomata, Kyohei,Akai, Shuji
supporting information, p. 4417 - 4422 (2021/07/16)
Direct nucleophilic substitution of alcohols with thiols or carbon nucleophiles was achieved using a mesoporous silica-supported oxovanadium catalyst (VMPS4). Benzyl and allyl alcohols were compatible in this reaction under mild conditions, affording the products in high yields. The VMPS4 catalyst showed excellent chemoselectivity toward alcohols in the presence of acid-labile functional groups, which is in contrast to that observed for the commonly used Lewis acid catalysts, which exhibit poor selectivity. The VMPS4 catalyst could be recycled by simple centrifugation, and the catalytic activity was maintained over seven cycles.
Molybdenum (VI)-catalyzed dehydrative construction of C[sbnd]O and C[sbnd]S bonds formation via etherification and thioetherification of alcohols and thiols
Singh, Rahulkumar Rajmani,Srivastava, Radhey S.,Whittington, Alex
, (2020/06/02)
An inexpensive, easily available, environmentally benign, and efficient catalyst molybdenum(VI) dioxo (acetylacetonate)2 was used for the direct oxo- and thioetherification of alcohol. This method endures selective molybdenum catalyzed dehydrative synthesis of symmetrical ethers from benzylic secondary alcohols as well as unsymmetrical ethers from the reaction of benzylic secondary alcohols with primary alcohol. Furthermore, we have been also successful in the synthesis of Aryl thioether by using alcohol and thiols.
Method for synthesizing ether by catalyzing alcohol through trimethyl halosilane
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Paragraph 0067-0070, (2020/12/29)
The invention discloses a method for synthesizing ether by catalyzing alcohol through trimethyl halosilane. According to the method, under the conditions of air or nitrogen atmosphere, no solvent andno transition metal catalyst, an alcohol compound is directly used as a raw material, trimethyl halosilane is used as a catalyst, and symmetric or asymmetric ether is synthesized through one-step selective dehydration reaction. According to the method, the use of strong acid, strong base and organic primary halides with high toxicity, instability and higher price is avoided, the synthesis steps are shortened, the synthesis efficiency is improved, the reaction has good selectivity, and a target ether product can be obtained preferentially.
Copper-catalyzed oxidative benzylic C(sp3)-H amination: Direct synthesis of benzylic carbamates
Liu, Shuai,Achou, Rapha?l,Boulanger, Coline,Pawar, Govind,Kumar, Nivesh,Lusseau, Jonathan,Robert, Frédéric,Landais, Yannick
supporting information, p. 13013 - 13016 (2020/11/05)
A new efficient strategy to access benzylic carbamates through C-H activation is reported. The use of a catalytic amount of a Cu(i)/diimine ligand in combination with NFSI ((PhSO2)2NF) or F-TEDA-PF6 as oxidants and H2NCO2R as an amine source directly leads to the C-N bond formation at the benzylic position. The mild reaction conditions and the broad substrate scope make this transformation a useful method for the late-stage incorporation of a ubiquitous carbamate fragment onto hydrocarbons. This journal is
