13481-09-9Relevant articles and documents
Copper nitrate/acetic acid as an efficient synergistic catalytic system for the chemoselective tetrahydropyranylation of alcohols and phenols
Wang, Min,Song, Zhi-Guo,Gong, Hong,Jiang, Heng
, p. 177 - 179 (2009)
Tetrahydropyranylation of alcohols and phenols was accomplished successfully using copper nitrate and acetic acid as a synergistic catalyst at room temperature under solvent-free condition. Compared with other synergistic catalytic systems, copper nitrate/acetic acid proved to be the most efficient. Both alcohols (primary, secondary, tertiary, benzylic, cyclic, allyl, cinnamyl, and furyl) and phenols reacted smoothly in high yields. Graphical abstract: [Figure not available: see fulltext.]
Metal benzenesulfonates/acetic acid mixtures as novel catalytic systems: Application to the protection of a hydroxyl group
Wang, Min,Gao, Jingjing,Song, Zhiguo
, p. 1349 - 1352 (2010)
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.
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.
Croconamides: A new dual hydrogen bond donating motif for anion recognition and organocatalysis
Jeppesen, Anne,Nielsen, Bjarne E.,Larsen, Dennis,Akselsen, Olivia M.,S?lling, Theis I.,Brock-Nannestad, Theis,Pittelkow, Michael
supporting information, p. 2784 - 2790 (2017/04/03)
We introduce bis-aryl croconamides as a new member in the family of dual hydrogen bonding anion receptors. In this study a series of croconamides are synthesised, and the selectivity for anion binding is investigated (Cl- > Br- > I- in CH2Cl2). The croconamides exhibit different structures in the crystal phase depending on the substituents on the aromatic rings, and furthermore, the crystal structure revealed the presence of tautomers. DFT calculations elucidated the complex structures formed upon addition of anion to the croconamides, confirming the order of association constants towards the halogen anions. The use of croconamides as organocatalysts in a proof-of-concept study is demonstrated in the formation of THP ethers. In addition to this, construction of a Hammet plot further elucidates the mechanism in action on formation of THP ethers.
Thiosemicarbazone organocatalysis: Tetrahydropyranylation and 2-deoxygalactosylation reactions and kinetics-based mechanistic investigation
Larsen, Dennis,Langhorn, Line M.,Akselsen, Olivia M.,Nielsen, Bjarne E.,Pittelkow, Michael
, p. 7978 - 7982 (2017/11/28)
The first use of thiosemicarbazone-based organocatalysis was demonstrated on both tetrahydropyranylation and 2-deoxygalactosylation reactions. The organocatalysts were optimised using kinetics-based selection. The best catalyst outperformed previously reported thiourea catalysts for tetrahydropyranylation by 50-fold. Hammett investigations of both the organocatalyst and the substrate indicate an oxyanion hole-like reaction mechanism.