Polystyrene-supported GaCl3: A new, highly efficient and recyclable heterogeneous Lewis acid catalyst for tetrahydropyranylation of alcohols and phenols
作者:Ali Rahmatpour
DOI:10.1016/j.poly.2012.06.063
日期:2012.8
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 Lewisacidcatalyst at room temperature is presented. In this catalytic system, primary, secondary and tertiary alcohols, as well as phenols, were converted to the corresponding
Cupric sulfate pentahydrate (CuSO4·5H2O): a mild and efficient catalyst for tetrahydropyranylation/depyranylation of alcohols and phenols
作者:Abu T. Khan、Lokman H. Choudhury、Subrata Ghosh
DOI:10.1016/j.tetlet.2004.08.141
日期:2004.10
Various alcohols and phenols can be smoothly converted to the corresponding THP ethers using 20 mol % CuSO4·5H2O under mild reaction conditions at room temperature. Some of the major advantages of this procedure are nonaqueous work-up, very good yields, less expensive catalyst and compatibility with other protecting groups.
Silica-Supported Perchloric Acid (HClO<sub>4</sub>-SiO<sub>2</sub>): A Versatile Catalyst for Tetrahydropyranylation, Oxathioacetalization and Thioacetalization
作者:Abu Khan、Tasneem Parvin、Lokman Choudhury
DOI:10.1055/s-2006-942465
日期:2006.8
A simple and convenient syntheticprotocol for the protection of hydroxyl group as tetrahydropyranyl ether as well as carbonyl functionality as oxathioacetal and thioacetal has been achieved using a catalytic amount of silica-supported perchloric acid undersolvent-freeconditions. This protocol has many advantages compared to currently available methodologies in terms of simplicity, yield, reaction
Several (1–6) 9-anthraceneacrylic esters were synthesized in order to study photochemical E(trans)–Z(cis) isomerization. All of the compounds 1–6 underwent selective E-to-Z isomerization upon direct excitation (> 400 nm) in organic solvents, leading to the formation of a thermodynamically less stable Z isomer over 96%. Triplet sensitized isomerization selectively produces the Z-to-E isomer in over
A Novel and Chemoselective Transformation of Alcohol Silyl Ethers into the Corresponding Tetrahydropyranyl Ethers
作者:Takeshi Suzuki、Takeshi Oriyama
DOI:10.1055/s-2001-12343
日期:——
Direct conversion of alcohol silyl ethers into the corresponding tetrahydropyranyl (THP) ethers can be easily performed by reaction with THP acetate under the influence of a catalytic amount of tert-butyldimethylsilyl trifluoromethanesulfonate (TBSOTf). Aliphatic TBS ether can be selectively transformed into the corresponding THP ether in the presence of phenolic TBS ether.