- Green preparation method α - hydroxyketone
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The invention relates to a green preparation method of alpha-hydroxyketone. The method comprises the following steps: adding ketone, iodine, 1,4-diazabicyclo[2.2.2]octane and methanol into a glass reaction bottle in sequence; then stirring and reacting for 14 to 30h at room temperature in an air atmosphere under the irradiation of a 23W compact type fluorescent lamp, so as to obtain a reaction mixture; carrying out silica gel column chromatographic separation to obtain the pure alpha-hydroxyketone. The green preparation method provided by the invention has the characteristics of greenness, high efficiency, simplicity in operation, moderate conditions, wide applicability and easiness for industrialization.
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Paragraph 0095-0098
(2020/08/27)
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- UV light-mediated difunctionalization of alkenes through aroyl radical addition/1,4-/1,2-Aryl shift cascade reactions
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UV light-mediated difunctionalization of alkenes through an aroyl radical addition/1,4-/1,2-aryl shift has been described. The resulted aroyl radical from a photocleavage reaction added to acrylamide compounds followed by cyclization led to the formation of oxindoles, whereas the addition to cinnamic amides aroused a unique 1,4-aryl shift reaction. Furthermore, the difunctionalization of alkenes of prop-2-en-1-ols was also achieved through aroyl radical addition and a sequential 1,2-aryl shift cascade reaction.
- Zheng, Lewei,Huang, Hongli,Yang, Chao,Xia, Wujiong
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supporting information
p. 1034 - 1037
(2015/03/30)
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- Mechanism of α-ketol-type rearrangement of benzoin derivatives under basic conditions
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The mechanism of base-catalyzed rearrangement of ring-substituted benzoins in aqueous methanol was examined by kinetic and product analyses. Substituent effects on the rate and equilibrium constants revealed that the kinetic process has a different electron demand compared to the equilibrium process. Reactions in deuterated solvents showed that the rate of H/D exchange of the α-hydrogen is similar to the overall rate toward the equilibrium state. A proton-inventory experiment using partially deuterated solvents showed a linear dependence of the rate on the deuterium fraction of the solvent, indicating that only one deuterium isotope effect contributes to the overall rate process. All these results point to a mechanism in which the rearrangement is initiated by the rate-determining α-hydrogen abstraction rather than a mechanism with initial hydroxyl hydrogen abstraction as in the general α-ketol rearrangement.
- Karino, Masahiro,Kubouchi, Daiki,Hamaoka, Kazuki,Umeyama, Shintaro,Yamataka, Hiroshi
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p. 7194 - 7198
(2013/08/23)
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- Chemoenzymatic synthesis of chiral unsymmetrical benzoin esters
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A chemoenzymatic Dynamic Kinetic Resolution (DKR) of unsymmetrical benzoins (Ar1≠Ar2) has been carried out, by using Pseudomonas stutzeri lipase stereorecognition pattern. After studying this lipase behaviour, a high preference towards acylation of those benzoins containing substituents in the phenyl ring rather than in the benzoyl moiety was observed. This fact allowed the development of the DKR process of this kind of substrates, avoiding the accumulation of secondary products derived from the in situ racemization mediated by Shvo's catalyst action, and allowing the synthesis of enantiopure unsymmetrical benzoins acetates (not previously described) in very good yields (60-95%) and excellent enantiomeric excess values (always >99%).
- Hoyos, Pilar,Pace, Vittorio,Sinisterra, José V.,Alcántara, Andrés R.
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p. 7321 - 7329
(2011/10/09)
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- Oxidation of benzoins to benzils using sodium hydride
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A highly efficient and eco-friendly oxidation of benzoins 1 to benzils 2 using sodium hydride has been developed.
- Joo, Cheonik,Kang, Sunhae,Kim, Sun Min,Han, Hogyu,Yang, Jung Woon
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experimental part
p. 6006 - 6007
(2010/11/21)
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- Antibody-Catalyzed Benzoin Oxidation as a Mechanistic Probe for Nucleophilic Catalysis by an Active Site Lysine
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Aldolase antibody 24H6, which was obtained by reactive immunization against a 1,3-diketone hapten, is shown to catalyze additional reactions, including H/D exchange and oxidation reactions. Comparison of the H/D exchange reaction at the α-position of a wide range of aldehydes and ketones by 24H6 and by other aldolase antibodies, such as 38C2, pointed at the significantly larger size of the 24H6 active site. This property allowed for the catalysis of the oxidation of substituted benzoins to benzils by potassium ferricyanide. This reaction was used as a mechanistic probe to learn about the initial steps of the 24H6-catalyzed aldol condensation reaction. The Hammett correlation (ρ=4.7) of log(kcat) versus the substituent constant, σ, revealed that the reaction involves rapid formation of a Schiff base intermediate from the ketone and an active site lysine residue. The rate-limiting step in this oxidation reaction is the conversion of the Schiff base to an enamine intermediate. In addition, linear correlation (ρ= 3.13) was found between log(KM) and σ, indicating that electronic rather than steric factors are dominant in the antibody-substrate binding phenomenon and confirming that the reversible formation of a Schiff base intermediate comprises part of the substrate-binding mechanism.
- Sklute, Genia,Oizerowich, Rachel,Shulman, Hagit,Keinan, Ehud
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p. 2159 - 2165
(2007/10/03)
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- Application of Cyanophosphates in Organic Synthesis. Reactivity of α-Cyano-α-diethylphosphonooxy Anions
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The utility of the cyanohydrin diethylphosphates derived from aldehydes (arylaldehydes,crotonaldehyde, and cinnamaldehyde) as an acyl anion equivalent was examined.Deprotonation of cyanophosphates with n-butyllithium in the presence of tetramethylethylene
- Kurihara, Takushi,Santo, Kazunori,Harusawa, Shinya,Yoneda, Ryuji
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p. 4777 - 4788
(2007/10/02)
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- Reduction of Unsymmetrical Benzils Using Sodium Dithionite
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Contrary to a previous report, reduction of unsymmetrical benzils by sodium dithionite (sodium hydrosulfite) in general yields a mixture of isomeric benzoins.Whereas the reduction of aldehydes and ketones by dithionite apparently takes place by a nucleophilic addition mechanism, the reduction of benzils proceeds by an electron-transfer mechanism.The initial product of the reduction is the (Z)-α,α'-stilbenediol which is produced stereospecifically.The ultimate benzoin products, then, result from the two different modes of ketolization of the stilbenediol intermediate.
- Heilmann, Steven M.,Rasmussen, Jerald K.,Smith, Howell K.
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p. 987 - 992
(2007/10/02)
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- Benzoin oxime fungicides
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Unwanted fungi are controlled by the use of certain benzoin oximes.
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