18483-99-3Relevant academic research and scientific papers
{[[K.18-Crown-6]Br3}n: A tribromide catalyst for the catalytic protection of amines and alcohols
Chehardoli, Gholamabbas,Zolfigol, Mohammad Ali,Derakhshanpanah, Fateme
, p. 1730 - 1733 (2013)
{[K.18-Crown-6]Br3}n, a unique tribromide-type catalyst, was utilized for the N-boc protection of amines and trimethylsilylation (TMS) and tetrahydropyranylation (THP) of alcohols. The method is general for the preparation of N-boc derivatives of aliphatic (acyclic and cyclic) and aromatic, and primary and secondary amines and also various TMS-ethers and THP-ethers. The simple separation of the catalyst from the product is one of the many advantages of this method.
Highly selective tetrahydropyranylation/dehydropyranylation of alcohols and phenols using porous phenolsulfonic acid-formaldehyde resin catalyst under solvent-free condition
Rajkumari, Kalyani,Laskar, Ikbal Bahar,Kumari, Anupama,Kalita, Bandita,Rokhum, Lalthazuala
, (2020/02/18)
An efficient protocol for solvent-free chemoselective tetrahydropyranylation/depyranylation of alcohols and phenols is reported herein using mesoporous Phenolsulfonic Acid Formaldehyde Resins as a heterogeneous acid catalyst. The catalyst successfully performed chemoselective protection and deprotection reactions of a wide range of substrates ranging from primary to secondary and tertiary alcohols and also phenols. The reactions were carried out at ambient temperature under solvent-free condition (SolFC) which resulted in high yields within a very short time. FT-IR, TEM, SEM, EDS and TG-DSC analysis techniques were employed to characterize the synthesized polymeric catalyst. The chemoselective nature of our method was confirmed using 13C DEPT-135 NMR studies. The polymer catalyst was found to be recoverable even after 10th catalytic cycle without much depreciation in its activity. The heterogeneity of the catalyst was verified by hot filtration method. Good yield, energy and cost- effective method, solvent-free protocol, mild reaction conditions, no inert atmosphere, metal-free heterogeneous polymer catalyst and excellent recoverability of the catalyst are notable milestones of the reported protocol.
KMnO4-catalyzed chemoselective deprotection of acetate and controllable deacetylation-oxidation in one pot
Gurawa, Aakanksha,Kumar, Manoj,Rao, Dodla S.,Kashyap, Sudhir
supporting information, p. 16702 - 16707 (2020/10/27)
A novel and efficient protocol for chemoselective deacetylation under ambient conditions was developed using catalytic KMnO4. The stoichiometric use of KMnO4 highlighted the dual role of a heterogeneous oxidant enabling direct access to aromatic aldehydes in one-pot sequential deacetylation-oxidation. The reaction employed an alternative solvent system and allowed the clean transformation of benzyl acetate to sensitive aldehyde in a single step while preventing over-oxidation to acids. Use of inexpensive and readily accessible KMnO4 as an environmentally benign reagent and the ease of the reaction operation were particularly attractive, and enabled the controlled oxidation and facile cleavage of acetate in a preceding step. This journal is
Cyclopropenium Enhanced Thiourea Catalysis
Smajlagic, Ivor,Durán, Rocio,Pilkington, Melanie,Dudding, Travis
supporting information, p. 13973 - 13980 (2018/11/21)
An integral part of modern organocatalysis is the development and application of thiourea catalysts. Here, as part of our program aimed at developing cyclopropenium catalysts, the synthesis of a thiourea-cyclopropenium organocatalyst with both cationic hydrogen-bond donor and electrostatic character is reported. The utility of the this thiourea organocatalyst is showcased in pyranylation reactions employing phenols, primary, secondary, and tertiary alcohols under operationally simple and mild reaction conditions for a broad substrate scope. The addition of benzoic acid as a co-catalyst facilitating cooperative Br?nsted acid catalysis was found to be valuable for reactions involving phenols and higher substituted alcohols. Mechanistic investigations, including kinetic and 1H NMR binding studies in conjunction with density function theory calculations, are described that collectively support a Br?nsted acid mode of catalysis.
Magnetic Fe3O4@silica sulfuric acid nanoparticles promoted regioselective protection/deprotection of alcohols with dihydropyran under solvent-free conditions
Rajkumari, Kalyani,Kalita, Juri,Das, Diparjun,Rokhum, Lalthazuala
, p. 56559 - 56565 (2017/12/27)
Protection (and deprotection) of hydroxyl groups via tetrahydropyranylation was carried out effectively using a catalytic amount of Fe3O4 supported silica sulphuric acid nanoparticles (Fe3O4@SiO2@SO3H) under solvent-free conditions. The synthesized nanocatalyst was characterized by XRD, TEM, FT-IR etc. A wide range of tetrahydropyranylated alcohol derivatives were synthesized using this heterogeneous magnetic nanocatalyst within 10-20 min with high yields. In addition, tetrahydropyranyl ethers could also be deprotected to the parent alcoholic compounds in the presence of MeOH using the same catalyst. After completion of the reactions, the catalyst was easily separated from the reaction medium using an external magnet, which ameliorated the overall synthetic process. The catalyst was recovered and reused for five successive reactions without any appreciable loss in its activity. Mild reactions conditions, operational simplicity, solvent free conditions, high selectivity, easy recyclability of the magnetic nanocatalyst, and high yields can be considered as the advantageous features of our procedure.
Magnetic nanoparticle-supported DABCO tribromide: A versatile nanocatalyst for the synthesis of quinazolinones and benzimidazoles and protection/deprotection of hydroxyl groups
Rostami, Amin,Pourshiani, Omid,Navasi, Yahya,Darvishi, Neda,Saadati, Shaghayegh
, p. 9033 - 9040 (2017/08/29)
1,4-Diazabicyclo[2.2.2]octane tribromide supported on magnetic Fe3O4 nanoparticles (MNPs-DABCO tribromide) as a novel heterogeneous tribromide type compound was found to be an efficient and reusable nanocatalyst for the one-pot synthesis of 2-arylquinazolin-4(3H)-ones and 2-aryl-1H-benzo[d]imidazoles through oxidative cyclization of aldehydes with 2-aminobenzamides and 1,2-phenylenediamine, respectively. Also, MNPs-DABCO tribromide catalyzed trimethylsilylation/tetrahydropyranylation and desilylation/depyranylation of a wide variety of alcohols and phenols through changing the solvent medium at room temperature.
Tetrahydropyranylation of alcohols and phenols catalyzed by a new multi-wall carbon nanotubes-bound tin(IV) porphyrin
Gharaati, Shadab,Kargar, Hadi,Falahati, Ali Mohammad
, p. 1169 - 1178 (2017/05/15)
Abstract: In the present study, tetrahydropyranylation of alcohols and phenols with 3,4-dihydro-2H-pyran (DHP) using tetrakis(p-aminophenyl)porphyrinatotin(IV) trifluoromethanesulfonate, [SnIV(TNH2PP)(OTf)2], and tetrakis(p-aminophenyl)porphyrinatotin(IV) tetrafluoroborate, [SnIV(TNH2PP)(BF4)2], supported on multi-wall carbon nanotubes as new catalytic systems is investigated. These new catalysts, [SnIV(TNH2PP)(OTf)2@MWCNT] and [SnIV(TNH2PP)(BF4)2@MWCNT], were characterized using elemental analysis, FT-IR spectroscopic techniques, scanning electron microscopy and diffuse reflectance UV–Vis spectroscopic methods. In these catalytic systems, an optimization on the amounts of catalysts and amount of DHP was done in the tetrahydropyranylation of alcohols and phenols with DHP and the best outcomes were received in the presence of 0.01?mmol (40?mg) of [SnIV(TNH2PP)(OTf)2@MWCNT] and [SnIV(TNH2PP)(BF4)2@MWCNT] with 2?mmol of DHP. Efficiency and reusability are two important features of these new heterogenized catalysts for tetrahydropyranylation of primary, secondary and tertiary alcohols as well as phenols at room temperature. These catalysts were recovered several times with no loss on their initial activity, which indicates their high reusability and stability. Graphical Abstract: In the present study, tetrahydropyranylation of alcohols and phenols with 3,4-dihydro-2H-pyran (DHP) using tetrakis(p-aminophenyl)porphyrinatotin(IV) trifluoromethanesulfonate, [SnIV(TNH2PP)(OTf)2], and tetrakis(p-aminophenyl)porphyrinatotin(IV) tetrafluoroborate, [SnIV(TNH2PP)(BF4)2], supported on multi-wall carbon nanotubes as new catalytic systems is investigated. These new catalysts, [SnIV(TNH2PP)(OTf)2@MWCNT] and [SnIV(TNH2PP)(BF4)2@MWCNT], were characterized using elemental analysis, FT-IR spectroscopic techniques, scanning electron microscopy and diffuse reflectance UV–Vis spectroscopic methods. In these catalytic systems, an optimization on the amounts of catalysts and amount of DHP was done in the tetrahydropyranylation of alcohols and phenols with DHP and the best outcomes were received in the presence of 0.01?mmol (40?mg) of [SnIV(TNH2PP)(OTf)2@MWCNT] and [SnIV(TNH2PP)(BF4)2@MWCNT] with 2?mmol of DHP. Efficiency and reusability are two important features of these new heterogenized catalysts for tetrahydropyranylation of primary, secondary and tertiary alcohols as well as phenols at room temperature. These catalysts were recovered several times with no loss on their initial activity, which indicates their high reusability and stability. [Figure not available: see fulltext.].
Light-promoted metal-free cross dehydrogenative couplings on ethers mediated by NFSI: Reactivity and mechanistic studies
Beniazza, Redouane,Abadie, Baptiste,Remisse, Lionel,Jardel, Damien,Lastécouères, Dominique,Vincent, Jean-Marc
supporting information, p. 12708 - 12711 (2017/12/02)
Cross dehydrogenative couplings on ethers occur very effectively using N-fluorobis(phenyl)sulfonimide (NFSI) as oxidizing agent under UVA irradiation in the presence of 2 mol% benzophenone. The reaction was shown to proceed first by fast radical fluorination of the α-C-H bond of ethers, followed by HF elimination to yield the highly electrophilic oxocarbenium ion as a key intermediate.
Selective tetrahydropyranylation of alcohols and phenols using titanium(IV) salophen trifluoromethanesulfonate as an efficient catalyst
Yadegari, Maryam,Moghadam, Majid
, p. 872 - 875 (2016/09/20)
Titanium(IV) salophen trifluoromethanesulfonate, [TiIV(salophen)(OSO2CF3)2], as a catalyst enables selective tetrahydropyranylation of alcohols and phenols with 3,4-dihydro-2H-pyran. Using this catalytic system, primary, secondary and tertiary alcohols, as well as phenols, were converted to their corresponding tetrahydropyranyl ethers in high yields and short reaction times at room temperature. Investigation of the chemoselectivity of this method showed discrimination between the activity of primary alcohols in the presence of secondary and tertiary alcohols and phenols. This heterogenized catalyst could be reused several times without loss of its catalytic activity. Copyright
