18484-04-3Relevant academic research and scientific papers
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.
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.
Solvent-free acetylation and tetrahydropyranylation of alcohols catalyzed by recyclable sulfonated ordered nanostructured carbon
Zareyee, Daryoush,Alizadeh, Parastoo,Ghandali, Mohammad S.,Khalilzadeh, Mohammad A.
, p. 713 - 721 (2013/07/26)
Rapid and practical green acetylation and tetrahydropyranylation routes of structurally diverse alcohols and phenols were applied under solvent-free reaction conditions providing excellent yields, using catalytic amounts of environmentally friendly sulfonated ordered nanoporous carbon (CMK-5-SO 3H). Non-toxic nature of the catalyst, its easy handling, recovery and reusability, and the absence of any solvent characterize the presented procedures as efficient methods. These procedures provide methods for the separation of the product by simple filtration.
Versatile gold catalyzed transglycosidation at ambient temperature
Kayastha, Abhijeet K.,Hotha, Srinivas
scheme or table, p. 7161 - 7163 (2012/07/31)
Glycosidation with stable alkyl glycosyl donors using a catalytic amount of gold salts is promising. Herein, 1-ethynylcyclohexanyl glycosides are identified as novel donors at room temperature and mechanistic investigation showed that the leaving group simply extrudes out.
Polystyrene-supported GaCl3: A new, highly efficient and recyclable heterogeneous Lewis acid catalyst for tetrahydropyranylation of alcohols and phenols
Rahmatpour, Ali
, p. 66 - 71,6 (2012/12/11)
A new, simple and highly chemoselective method for tetrahydropyranylation of alcohols and phenols with 3,4-dihydro-2H-pyran (DHP) in the presence of polystyrene-supported gallium trichloride (PS/GaCl3) as a highly active and reusable heterogeneous Lewis acid catalyst at room temperature is presented.
Tetrahydropyranylation of alcohols under solvent-free conditions
Hajipour, Abdol R.,Kargosha, Majid,Ruoho, Arnold E.
experimental part, p. 1084 - 1091 (2009/09/08)
A green, efficient, and large-scale method for tetrahydropyranylation of alcohols in the presence of a catalytic amount of pyridinium chloride at room temperature under solvent-free conditions is reported. Copyright Taylor & Francis Group, LLC.
N-Bromosuccinimide (NBS): A mild and efficient catalyst for tetrahydropyranylation of alcohols and phenols under solvent-free conditions
Khazaei, Ardeshir,Rostami, Amin,Raiatzadeh, Ayeh
, p. 1029 - 1032 (2008/03/11)
Different types of alcohols and phenols are tetrahydropyranylated in the presence of NBS catalyst in good to excellent yields under mild, neutral and solvent-free conditions.
Efficient and convenient procedure for protection of hydroxyl groups to the THP, THF and TMS ethers and oxidation of these ethers to their aldehydes or ketones in [BPy]FeCl4 as a low cost room temperature ionic liquid
Khosropour, Ahmad R.,Khodaei, Mohammad M.,Ghaderi, Sattar
, p. 326 - 330 (2007/10/03)
Alcohols were converted to the corresponding THP, THF or TMS ethers in high to excellent yields in 1-n-butylpyridinium chloroferrate media as a stable and low cost room temperature ionic liquid. In addition, oxidation of these ethers to their aldehydes or ketones without any overoxidation reactions in this ionic liquid was also performed.
Efficient tetrahydropyranylation of alcohols and detetrahydropyranylation reactions in the presence of catalytic amount of trichloroisocyanuric acid (TCCA) as a safe, cheap industrial chemical
Firouzabadi, Habib,Iranpoor, Nasser,Hazarkhani, Hassan
, p. 3623 - 3630 (2007/10/03)
Preparation and cleavage of THP ethers of different hydroxy functional groups are easily and efficiently performed in the presence of trichloroisocyanuric acid (TCCA) in the absence of solvent with high yields.
