- Formation of δ-Lactones by cyanide catalyzed rearrangement of α-Hydroxy-β-oxoesters
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δ-Valerolactone derivatives are formed by cyanide-catalyzed ring-transformation of cyclic α-hydroxy-β-oxoesters. This unprecedented reaction defines a new synthetic methodology, and the products are obtained in up to quantitative yields. Several alkyl substitutions as well as different ester residues are tolerated. Furthermore, benzo- and heteroarene-annulated starting materials are converted without problems. As an additional benefit, the starting materials are straightforwardly accessed by cerium-catalyzed aerobic α-hydroxylation of readily available β-oxoesters.
- Kieslich, David,Christoffers, Jens
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supporting information
p. 953 - 957
(2021/02/06)
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- Reactions of hydrogen peroxide with acetylacetone and 2- acetylcyclopentanone
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A reaction of acetylacetone with equimolar amount of concentrated aqueous H2O2 in both organic solvents (ButOH, AcOH) and water at various temperatures gave the corresponding 3,5-dihydroxy-1,2- dioxolanes with different configuration of stereogenic centers. In the pres-ence of an excess of H2O2, 3,5-dihydroxy-1,2-dioxolanes were converted to a mixture of 5-hydroperoxy-3-hydroxy-1,2-dioxolanes and further to a mixture of dimeric 1,2-dioxolan-3-ylperoxides. All the peroxides formed exist in solutions as equilibrium mixtures with the starting reagents. A prolonged reflux of solutions of 3,5-dihydroxy-1,2-dioxolanes in ButOH in the presence of a large excess of H2O2 led to the skeletal rearrangements of the substrates to a mixture of propionic acid and hydroxyacetone, which underwent further oxidative transfor-mations. Unlike acetylacetone, 2-acetylcyclopentanone reacted with H2O2 in aqueous phase or in solutions in ButOH under thermodynamic or kinetic control with the formation of the corresponding 5-hydroperoxy-3-hydroxy- 1,2-dioxolanes, rather than 3,5-dihydroxy-1,2-di-oxolanes. Thermodynamically controlled process in solution in AcOH gave a mixture of all four possible hydroperoxyhydroxy-1,2-dioxolanes. These cyclic peroxides in solutions in ButOH or AcOH readily converted to a mixture of AcOH, glutaric, α-methyladipic, and α-hydroxy-α-methyladipic acids. An active α-hydroxylation of the substrate was observed upon reflux of a solution of 2-acetylcyclopentanone and H2O2 in AcOH.
- Novikov,Shestak
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p. 2171 - 2190
(2014/11/07)
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- Thermal and photochemical oxidation of 2-acetylcyclopentanone with atmospheric oxygen
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The major products of thermal (acetone, CaCl2 excess, reflux) and photochemical (acetone or CCl4, room temperature) oxidation of 2-acetylcyclopentanone with atmospheric oxygen are 2-acetyl-2- hydroxycyclopentanone, 2-acetyl-2-hydroxy
- Novikov,Shestak
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p. 1099 - 1110
(2013/07/26)
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- Chemistry of Dioxiranes. 21. Thermal Reactions of Dioxiranes
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Thermolysis of dioxiranes in solutions of their parent ketones or in mixtures of the parent ketone and a foreign ketone leads to the formation of esters.The results are explained by postulating a free-radical mechanism involving H atom abstraction from the ketones.The resulting radicals are converted to the observed esters by reaction with acyloxy radicals derived from homolysis of the dioxiranes.Autodecomposition of dimethyldioxirane in acetone solution at room temperature gives methyl acetate at a very slow rate.When catalyzed by BF3 etherate the same decomposition proceeds much more rapidly and is accompanied by acetol formation.
- Singh, Megh,Murray, Robert W.
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p. 4263 - 4270
(2007/10/02)
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- REACTIVITY OF ORGANOTIN COMPOUNDS. XXIII. REACTION OF LEAD TETRAACETATE WITH TRIETHYLSTANNYL AND TRIMETHYLSILYL ETHERS OF THE ENOLS OF CYCLIC KETONES AS A METHOD FOR THE PRODUCTION OF 2-ACETOXY KETONES
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The reactions of 1-cyclohexenyloxytriethyltin with lead tetraacetate and (diacetoxyiodo)benzene and the reaction of the trimethylsilyl ethers of the enols of cyclopentanone, cyclohexanone, 2-methylcyclohexanone (2-methyl-1-cyclohexenyloxytrimethylsilane and 6-methyl-1-cyclohexenyloxytrimethylsilane), cholestan-3-one, dl-camphor, and 1-methone with lead tetraacetate at room temperature in methylene chloride were investigated.The reaction of 1-cyclohexenyloxytriethyltin with lead tetraacetate and (diacetoxyiodo)benzene leads to the formation of 2-acetoxycyclohexanone and 2,2'-dioxo-1,1'-bicyclohexyl. 1-Cyclohexenyloxytrimethylsilane reacts with lead tetraacetate, giving (1,2-diacetoxycyclohexyloxy)trimethylsilane and (2-acetoxy-1-cyclo-hexenyloxy)trimethylsilane.As a result of the reactions of the trimethylsilyl ethers of the ketone enols with lead tetraacetate after treatment with BF3Et2O the corresponding 2-acetoxy ketones are obtained.The reaction mechanisms are discussed.
- Kashin, A. N.,Tul'chinskii, M. L.,Bumagin, N. A.,Beletskaya, I. P.,Reutov, O. A.
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p. 1390 - 1395
(2007/10/02)
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- The Chemistry of Aryllead(IV) Tricarboxylates. Reaction with Enamines
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The treatment of 1-morhpholinocyclopentene (1a) with p-methoxyphenyllead triacetate (2a) in chloroform provides a simple high-yielding route to 2-(4-methoxyphenyl)cyclopentanone (3a).This arylation reaction of enamines has been investigated with a variety of substrates and a number of aryllead triacetates.The reaction has been found to be very sensitive to steric effects and is thus a useful synthetic method in a relatively small number of cases.Acetoxylation is a major competing reaction with those enamines of cyclic ketones which give a low to moderate yield of arylated product.
- May, George L.,Pinhey, John T.
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p. 1859 - 1871
(2007/10/02)
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