CARO'S ACID SUPPORTED ON SILICA GEL. PART VI. A MILD REAGENT FOR REGENERATION OF CARBONYL COMPOUNDS FROM ACETALS, KETALS, AND 1,1-DIACETATES
作者:M. M. Lakouraj、M. Tajbakhsh、V. Khojasteh、M. H. Gholami
DOI:10.1080/10426500490494750
日期:2004.12.1
Efficient conversion of acetals, ketals, and diacetates to carbonylcompounds is described using Caro's acid supported on silica gel. The deacetalization reactions are carried out in acetonitrile at room temperature. Reaction of diacetates is performed in refluxing dichloromethane, and their parent carbonylcompounds are obtained in good-to-excellent yields.
使用负载在硅胶上的 Caro 酸描述了缩醛、缩酮和二乙酸酯向羰基化合物的有效转化。脱缩醛反应在室温下在乙腈中进行。双乙酸酯在回流二氯甲烷中反应,得到母体羰基化合物,产率从优到优。
Solvent free protection of carbonyl group under microwave irradiation
Protection of aldehydes and ketones as acetals or dioxolanes catalysed by PTSA or KSF clay was readily achieved from orthoformates, 1,2-ethanediol or 2,2-dimethyl-1,3-dioxolane without solvent under microwave irradiation.
Syntheses and evaluation of ketals, hemithioketals, and dithioketals of conjugated styryl ketones principally for antineoplastic activity
作者:J.R. Dimmock、L.M. Smith
DOI:10.1002/jps.2600690527
日期:1980.5
Ketals, hemithioketals, and dithioketals of nuclear-substituted styrylketones were prepared as latentiated forms of the ketones. This undertaking was based on the premise that there is increased acidity in tumors compared to normal tissue, and thus preferential regeneration of the ketone in neoplastic tissue may occur. Attempts to form 1,3-dioxolans of Mannich bases were unsuccessful. The prepared
The first asymmetricchiral N-triflylphosphoramide-catalyzed ionic [2+4] cycloaddition reaction of unsaturated acetals is described. This reaction proceeds through the intermediacy of a vinyl oxocarbenium/chiral anion pair, and the chiral N-triflylphosphoramide anion controls the stereoselectivity of the cycloaddition step. Moderate enantioselectivities (up to 80:20 e.r.) have been obtained when α
1,3-Dioxolan-2-ylium cations derived from α,β-unsaturated aldehyde ethylene acetals regioselectively react with lithium organocuprate and lithium organoaluminate to give the corresponding esters and ketals, respectively.