Transacetalation: a convenient, nonaqueous method for effecting the deprotection of isopropylidene and benzylidene derivatives of sugars
作者:Mark A. Andrews、George L. Gould
DOI:10.1016/s0008-6215(00)90486-5
日期:1992.5
Abstract Sugar isopropylidene and benzylidene derivatives can be readily deprotected under nonaqueous conditions by treatment of a dichloromethane solution of the protected sugar with an excess of a sacrificial glycol in the presence of a catalytic amount of p -toluenesulfonic acid. The reaction is conveniently monitored by GLC, and the fully or partially deprotected product precipitates from solution
Cu(OTf)<sub>2</sub>-Catalyzed Selective Opening of Aryl and Vinyl Epoxides with Carbonyl Compounds to Give 1,3-Dioxolanes
作者:Pavel Krasik、Mathieu Bohemier-Bernard、Qing Yu
DOI:10.1055/s-2005-864795
日期:——
Copper(II) triflate catalyzes the ring-opening of aryl- and vinyl-substituted epoxides with various carbonyl compounds to furnish 1,3-dioxolanes under mild conditions. Alkyl- and alkoxycarbonyl-substituted epoxides remainunchanged under reaction conditions. This allows selective opening of aryl-substituted epoxides in the presence of alkyl-substituted ones.
三氟甲磺酸铜 (II) 催化芳基和乙烯基取代的环氧化物与各种羰基化合物的开环,在温和条件下提供 1,3-二氧戊环。烷基和烷氧基羰基取代的环氧化物在反应条件下保持不变。这允许在烷基取代的环氧化物存在下选择性地打开芳基取代的环氧化物。
Stereoelectronic effects in the DIBAL reduction of aryl-1,2-ethanediol benzylidene acetals
作者:Donald R Gauthier、Ronald H Szumigala、Joseph D Armstrong、R.P Volante
DOI:10.1016/s0040-4039(01)01466-6
日期:2001.10
Reduction of benzylidene acetal 8 with DIBAL-H selectively gave 4 in 89% yield. 1-Aryl-1,2-diol benzylidene acetals display unusual regioselectivity with electron withdrawing groups on the aryl group.
hectorite and FeOx-pillared taeniolite) were synthesized by the intercalation of FeCl3 into clay interlayers and calcination. The synthesized catalysts were exploited for conversion of epoxides furnishing acetonides in good to quantitative yields with short time under mild conditions. The catalysts could be recovered and reused up to five times without appreciable loss of activity.
<i>N</i>-Benzyl Pyridinium Salts as New Useful Catalysts for Transformation of Epoxides to Cyclic Acetals, Orthoesters, and Orthocarbonates
作者:Sang-Bong Lee、Toshikazu Takata、Takeshi Endo
DOI:10.1246/cl.1990.2019
日期:1990.11
In the presence of catalytic amount of N-(4-methoxybenzyl)-2-cyanopyridinium hexafluoroantimonate, the reaction of a few epoxides with aldehydes, ketones, lactones, and carbonates efficiently afforded corresponding cyclic acetals, orthoesters, and Orthocarbonates under mild conditions.