72020-06-5Relevant articles and documents
Copper-Catalyzed Oxidative Acetalization of Boronic Esters: An Umpolung Strategy for Cyclic Acetal Synthesis
Miller, Eric M.,Walczak, MacIej A.
, p. 8230 - 8239 (2020/07/15)
A protocol for the acetalization of boronic esters is described. The reaction is catalyzed by copper, and the conditions proved to be mild and were amenable to a variety of functional groups. We expanded the Chan-Lam coupling to include C(sp3) nucleophiles and converted them into corresponding acetals. This method allows for the orthogonal acetalization of substrates with reactive, acid-sensitive functional groups.
Heterogeneous acidic catalysts for the tetrahydropyranylation of alcohols and phenols in green ethereal solvents
Azzena, Ugo,Carraro, Massimo,Modugno, Gloria,Pisano, Luisa,Urtis, Luigi
supporting information, p. 1655 - 1659 (2018/07/25)
The application of heterogeneous catalysis and green solvents to the set up of widely employed reactions is a challenge in contemporary organic chemistry. We applied such an approach to the synthesis and further conversion of tetrahydropyranyl ethers, an important class of compounds widely employed in multistep syntheses. Several alcohols and phenols were almost quantitatively converted into the corresponding tetrahydropyranyl ethers in cyclopentyl methyl ether or 2-methyltetrahydrofuran employing NH4HSO4 supported on SiO2 as a recyclable acidic catalyst. Easy work up of the reaction mixtures and the versatility of the solvents allowed further conversion of the reaction products under one-pot reaction conditions.
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.
P4VPy–CuO nanoparticles as a novel and reusable catalyst: application at the protection of alcohols, phenols and amines
Shirini, Farhad,Fallah-Shojaei, Abdollah,Abedini, Masoumeh,Samavi, Laleh
, p. 1699 - 1712 (2016/07/27)
P4VPy–CuO nanoparticles were synthesized using ultrasound irradiations. Relevant properties of the synthesized nanoparticles were investigated by X-ray diffraction, scanning electron microscopy, transmission electron microscopy and Fourier transform infrared spectroscopy. After identification, the prepared reagent was used for the promotion of different types of protection reactions of alcohols, phenols and amines. Easy workup, short reaction times, excellent yields, relatively low cost and reusability of the catalyst are the striking features of the reported methods.
Supported N-propylsulfamic acid onto Fe3O4 magnetic nanoparticles as a reusable and efficient nanocatalyst for the protection/deprotection of hydroxyl groups and protection of aldehydes
Rostami, Amin,Tahmasbi, Bahman,Abedi, Fatemeh
, p. 3689 - 3701 (2016/04/05)
N-propylsulfamic acid supported onto Fe3O4 magnetic nanoparticles (MNPs-PSA) as an efficient and magnetically reusable nanocatalyst has been reported for the tetrahydropyranylation/depyranylation of a wide variety of alcohols and phenols by changing the solvent medium. Also, the protection of aldehydes as acylals using Ac2O in the presence of catalytic amount MNPs-PSA in good to high yields at room temperature under solvent-free conditions is described. After completing the reaction, the catalyst was easily separated from the reaction mixture with the assistance of an external magnetic field and reused for several consecutive runs without significant loss of their catalytic efficiency.
An efficient Br?nsted–Lewis acidic ionic liquid catalyzed tetrahydropyranylation of alcohols
Azizi, Najmedin,Abdoli-Senejani, Masumeh,Abbasi, Faezeh
, p. 5009 - 5011 (2016/10/24)
An imidazolium based Br?nsted–Lewis acidic ionic liquid has been shown to be an excellent catalyst and reaction medium for the tetrahydropyranylation of various alcohols in good to excellent yields with short reaction times. Selective protection of benzyl
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.
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.
Anhydrous FePO4 as a cost-effective and recyclable catalyst for tetrahydropyranylation and tetrahydrofuranylation of alcohols and phenols
Behbahani, Farahnaz K.,Farahani, Mona
experimental part, p. 431 - 435 (2012/04/17)
In this article, a mild and efficient protocol for the tetrahydropyranylation and tetrahydrofuranylation of various aliphatic and benzylic alcohols and phenols into their corresponding THP and THF ethers (with 3,4-dihydro- 2H-pyran, DHP and 2,3-dihydrofuran, DHF) has been developed using a catalytic amount of anhydrous FePO4 at room temperature and relatively short reaction times in good to excellent yields.
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.
