Highly Stereoselective Synthesis of <i>cis</i>-2-Substituted-3-vinyltetrahydrofurans from (<i>Z</i>)-Trimethyl(5-trimethylsiloxy-2-pentenyl)silane and Acetals
作者:Tomohumi Sano、Takeshi Oriyama
DOI:10.1055/s-1997-3261
日期:1997.6
A variety of cis-2-substituted-3-vinyltetrahydrofurans are easily and stereoselectively produced by the reaction of acetals with (Z)-trimethyl(5-trimethylsiloxy-2-pentenyl)silane under the influence of a catalytic amount of trimethylsilyl trifluoromethanesulfonate under very mild conditions.
A highly chemo- and stereo-selective cleavage of acetals derived from (−)(2R,4R)-2,4-pentanediol with organoaluminum and organotitanium reagents has been demonstrated. The reactions proceed under mild conditions with excellent yields and high chemoselectivities to give, after removal of the auxiliary, chiral alcohols of high enantiomeric purities.
Photocatalytic Reductive Formation of α-Tertiary Ethers from Ketals
作者:Thomas Rossolini、Branislav Ferko、Darren J. Dixon
DOI:10.1021/acs.orglett.9b02273
日期:2019.9.6
unsymmetrical α-tertiary dialkyl ethers is reported. By merging Lewis acid-mediated ketal activation and visible-light photocatalytic reduction, in situ-generated α-alkoxy radicals were found to engage in addition reactions with a variety of olefinic partners. Good reaction efficiency is demonstrated with a range of ketals of aromatic and aliphatic ketones. Extension to acetal substrates is also described
Formation of Acetals and Ketals from Carbonyl Compounds: A New and Highly Efficient Method Inspired by Cationic Palladium
作者:Enoch A. Mensah、Shawn D. Green、Jesse West、Tyler Kindoll、Brenda Lazaro-Martinez
DOI:10.1055/s-0039-1690497
日期:2019.9
acetals and ketals is described. This methodology relies on the nature of the palladium catalyst to direct the acetalization/ketalization reaction. This new protocol is mild and proceed with a very low catalyst loading at ambient temperatures. The method has been extended to a wide variety of different carbonyl compounds with various steric encumbrances to form the corresponding acetals and ketals in excellent