1927-70-4Relevant academic research and scientific papers
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.
BiCl3: A versatile catalyst for the tetrahydropyranylation and depyranylation of 1°,2°,3°, allylic, benzylic alcohols, and symmetric diols
Vijaya Durga,Balamurali Krishna,Baby Ramana,Santha Kumari,Vijay,Hari Babu
, p. 1030 - 1034 (2017/05/26)
Bismuth trichloride as mild reagent, has been found to be a worthful catalyst for tetrahydropyranylation of 1°,2°,3°, allylic, benzylic alcohols, and symmetric di-ols. At room temperature the reagent THP(3,4-dihydro-2H-pyran) was successfully employed as pyranylating agent in presence of BiCl3catalyst without the use of a solvent and the yields of the products were found to be 90-96%. Further, the depyranylation of alcohols was achieved in quantitative yield by simple addition of MeOH using the same catalyst. The developed method was showed good chemo-selectivity in symmetrical diols for mono THP protection.
Facile O-glycosylation of glycals using Glu-Fe3O4-SO3H, a magnetic solid acid catalyst
Thombal, Raju S.,Jadhav, Vrushali H.
, p. 30846 - 30851 (2016/04/09)
A new glucose derived magnetic solid acid catalyst (Glu-Fe3O4-SO3H) was synthesized in a convenient and ecofriendly manner and well characterized using FTIR, PXRD, EDAX, SEM, and XPS which showed the presence of Fe3/
Organocatalyzed direct glycosylation of unprotected and unactivated carbohydrates
Schmalisch, Sebastian,Mahrwald, Rainer
supporting information, p. 5854 - 5857 (2013/12/04)
Organocatalyzed direct glycosylation of unprotected and unactivated carbohydrates is reported. This process is catalyzed by triphenylphosphine and tetrabromomethane at room temperature under neutral conditions. With this operationally simple protocol thermodynamically favored, glycosides were obtained in a very straightforward reaction.
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.
Mild and efficient chemoselective tetrahydropyranylation of alcohols using bronsted acidic ionic liquid as catalyst under solvent-free conditions
Hajipour, Abdol R.,Nasresfahani, Zahra
experimental part, p. 1995 - 2006 (2012/06/04)
A straightforward and efficient method for preparation of morpholinium bisulfate ([mroH]HSO4) as a novel acidic ionic liquid is reported. The application of this efficient and inexpensive acidic ionic liquid catalyst for tetrahydropyranylation of alcohols under mild and solvent-free conditions at room was investigated.
Direct glycosylation of unprotected and unactivated carbohydrates under mild conditions
Pfaffe, Matthias,Mahrwald, Rainer
supporting information; experimental part, p. 792 - 795 (2012/05/04)
Ligand exchange acetalization of acetals in the presence of catalytic amounts of mandelic acid and titanium tert-butoxide is reported. This transformation is successfully extended to glycosylation of unprotected and unactivated pentoses. Even unreactive pentoses such as d-arabinose or d-lyxose can be transformed by this new methodology into corresponding isopropyl glycosides.
Solvent-free tetrahydropyranylation of alcohols catalyzed by amine methanesulfonates
Wang, Rui,Sun, Mingzhu,Jiang, Heng
experimental part, p. 61 - 67 (2012/02/16)
A comparative study of tetrahydropyranylation of alcohols under various solvents or solvent-free conditions using different amine methanesulfonates as catalysts shows that tetrahydropyranyl ethers of alcohols are obtained under solvent-free conditions in good yields using catalytic amounts of triethylenediamine methanesulfonate, 1,6-hexanediamine methanesulfonate, diethylenetriamine methanesulfonate and pyridine methanesulfonate, respectively. The reaction occurs readily in short times at room temperature catalyzed by these catalysts, especially triethylenediamine methanesulfonate. Some of the major advantages of this procedure are that the catalysts are environmentally friendly, highly effective, and easy to prepare and handle. The reaction is also clean and needs no solvent, and the work-up is very simple.
Metal benzenesulfonates/acetic acid mixtures as novel catalytic systems: Application to the protection of a hydroxyl group
Wang, Min,Gao, Jingjing,Song, Zhiguo
experimental part, p. 1349 - 1352 (2011/01/11)
A surprising synergistic effect has been discovered in mixtures of metal benzenesulfonates (Co, Al, Ni, Zn, Cd, Pr, La, Cu, Mn) and acetic acid, leading to active catalytic systems for the tetrahydropyranylation of alcohols and phenols to produce tetrahydropyranyl ethers. All reactions proceed mildly and efficiently with moderate to high yields at room temperature without solvent. After the reaction, the metal benzenesulfonate can be easily recovered and reused many times. The efficiency of these systems might result from the "double activation" by Bronsted and Lewis acid catalysis.
Poly(N-bromo-N-ethyl-benzene-1,3-disulfonamide), N,N,N′,N′- tetrabromobenzene-1, 3-disulfonamide as new efficient reagents for conversion of alcohols to THP ethers and aldehydes to oxazoline compounds
Ghorbani-Vaghei,Akbari-Dadamahaleh,Amiri
experimental part, p. 301 - 307 (2010/09/03)
This paper is concerned with an easy preparation of THP ethers from primary, secondary and tertiary alcohols and oxazoline compounds from various aldehydes using poly(N-bromo-N-ethyl-benzene-1,3-disulfonamide), N,N,N′,N′-tetrabromobenzene-1,3-disulfonamide [TBBDA] as new and efficient reagents under ambient conditions without over-oxidation.
