Sc(OTf)3, an Efficient Catalyst for Formation and Deprotection of Geminal Diacetates (Acylals); Chemoselective Protection of Aldehydes in Presence of Ketones
Thallium(III) Chloride: A Mild
and Efficient Catalyst for Acylation of Alcohols, Phenols
and Thiols, and for Geminal Diacylation of Aldehydes under
Solvent-Free Conditions
作者:Sung Kim、Santosh Kadam
DOI:10.1055/s-0028-1083148
日期:——
simple and efficientcatalyst for acylation of alcohols, phenols and thiols. It is also very effective for geminal diacylation of aldehydes. The acylation reaction using acetic anhydride proceeds in excellent yield in the presence of catalytic amounts ofthallium(III) chloride (1 mol%) at room temperature within relatively short reaction times (<20 min). Structurally diverse alcohols, phenols, thiols and
Conversion of Aldehydes into Geminal Dicarboxylates (Acylals) Catalyzed by Lithium Tetrafluoroborate
作者:Norihiko Sumida、Kuniaki Nishioka、Tsuneo Sato
DOI:10.1055/s-2001-18774
日期:——
A variety of aldehydes react with acid anhydrides in the presence of a catalytic amount of lithium tetrafluoroborate to afford the corresponding geminal dicarboxylates (acylals) in good to excellent yields.
Chemoselective synthesis and deprotection of 1,1-diacetates have been performed in good yields and in the absence of any solvent by zeolite HSZ-360 as a new reusable catalyst.
The Chemistry of Acylals. 3. Cyanohydrin Esters from Acylals with Cyanide Reagents
作者:Marcel Sandberg、Leiv K. Sydnes
DOI:10.1021/ol005535b
日期:2000.3.1
[reaction: see text] When treated with KCN in DMSO at room temperature, acylals from aliphatic aldehydes gave the corresponding cyanohydrin esters in good to excellent yields. Acylals from aromatic aldehydes were less reactive and gave several byproducts in addition to fair yields of cyanohydrin under the same conditions. Trimethylsilyl cyanide mixed with titanium(IV) chloride afforded cyanohydrin
Scandium Triflate Catalyzed Allylation of Acetals and <i>gem</i>-Diacetates: A Facile Synthesis of Homoallyl Ethers and Acetates
作者:Jhillu S. Yadav、Basi V. Subba Reddy、P. Srihari
DOI:10.1055/s-2001-13379
日期:——
Scandium triflate catalyzes efficiently the allylation reactions of acetals and gem-diacetates with allyltrimethylsilane at ambient temperature to afford the corresponding homoallyl ethers and acetates in high yields. Also it is found to be effective for the direct formation of homoallyl ethers from aldehydes and allylsilane in presence of trimethylorthoformate.