1424-22-2Relevant articles and documents
A convenient and selective method for preparation of enol acetates from ketones using montmorillonite KSF clay
Kalita, Biswajit,Bezbarua, Maitreyee Sarma,Barua, Nabin C.
, p. 3181 - 3184 (2002)
The reaction of ketones with stoichiometric amounts of acetic anhydride and Montmorillonite KSF clay at room temperature afforded the corresponding enol acetates in excellent yields. It has also been observed that by performing the reactions under microwave irradiation the reaction time can be dramatically reduced.
A selective catalytic method of enol-acetylation under microwave Irradiation
Kalita, Dipok J.,Borah, Ruli,Sarma, Jadab C.
, p. 404 - 405 (1999)
Six-membered cyclic ketones on treatment with acetic anhydride and a catalytic amount of iodine under microwave irradiation give the corresponding enol acetates in good yield.
Porphyrins as Photoredox Catalysts in Csp2-H Arylations: Batch and Continuous Flow Approaches
De Souza, Aline A. N.,Silva, Nathalia S.,Müller, Andressa V.,Polo, André S.,Brocksom, Timothy J.,De Oliveira, Kleber T.
, p. 15077 - 15086 (2019/01/03)
We have investigated both batch and continuous flow photoarylations of enol-acetates to yield different α-arylated aldehyde and ketone building blocks by using diazonium salts as the aryl-radical source. Different porphyrins were used as SET photocatalysts, and photophysical as well as electrochemical studies were performed to rationalize the photoredox properties and suggest mechanistic insights. Notably, the most electron-deficient porphyrin (meso-tetra(pentafluorophenyl)porphyrin) shows the best photoactivity as an electron donor in the triplet excited state, which was rationalized by the redox potentials of excited states and the turnover of the porphyrins in the photocatalytic cycle. A two-step continuous protocol and multigram-scale reactions are also presented revealing a robust, cost-competitive, and easy methodology, highlighting the significant potential of porphyrins as SET photocatalysts.
Study of the Reactivity of [Hydroxy(tosyloxy)iodo]benzene Toward Enol Esters to Access α-Tosyloxy Ketones
Basdevant, Benoit,Legault, Claude Y.
, p. 6897 - 6902 (2015/10/06)
The reactivity of enol esters toward [hydroxy(tosyloxy)iodo]benzene (HTIB) was assessed. These substrates were found to be rapidly converted in high yields to their corresponding α-tosyloxy ketones. This transformation demonstrates that these substrates can act as ketone surrogates. The scope of the method was investigated and aromatic, aliphatic, and cyclic enol esters were found to be suitable substrates for the reaction. The relative reactivity of a model substrate toward HTIB and m-CPBA was investigated, and it was found that the reaction could be performed under catalytic conditions.
Enantioselective Iodine(III)-Mediated Synthesis of α-Tosyloxy Ketones: Breaking the Selectivity Barrier
Basdevant, Benoit,Legault, Claude Y.
supporting information, p. 4918 - 4921 (2015/10/12)
The development of practical methods to access chiral nonracemic α-substituted ketones is of particular importance due to their ubiquitous nature. Unprecedented levels of enantioselectivity are reported for the synthesis of α-tosyloxy ketones, using enol esters and chiral iodine(III) reagents. The reaction can be performed under both stoichiometric and catalytic conditions. These results suggest widely different reaction mechanisms for the reaction of ketones versus enol esters, supporting recent computational insights.
InCl3/Me3SiCl-catalyzed direct michael addition of enol acetates to α,β-unsaturated ketones
Onishi, Yoshiharu,Yoneda, Yuki,Nishimoto, Yoshihiro,Yasuda, Makoto,Baba, Akio
supporting information, p. 5788 - 5791 (2013/01/15)
The direct Michael addition of enol acetates to α,β-unsaturated ketones was achieved using a combination of Lewis acid catalysts, InCl 3 and Me3SiCl, which furnished stable enol-form products that could be further transformed into functionalized 1,5-diketones by reactions with various electrophiles.
Visible-light-mediated α-arylation of enol acetates using aryl diazonium salts
Hering, Thea,Hari, Durga Prasad,Koenig, Burkhard
, p. 10347 - 10352 (2013/01/15)
Visible light mediates efficiently the α-arylation of enol acetates by aryl diazonium salts under mild conditions using [Ru(bpy)3]Cl 2 as a photoredox catalyst. The broad scope of the reaction toward various diazonium salts and enol acetates was explored. The application of this reaction in the concise synthesis of 2-substituted indoles was demonstrated
InCl3/Me3SiBr-catalyzed direct coupling between silyl ethers and enol acetates
Onishi, Yoshiharu,Nishimoto, Yoshihiro,Yasuda, Makoto,Baba, Akio
supporting information; experimental part, p. 2762 - 2765 (2011/08/02)
A combined Lewis acid catalyst of InCl3 and Me3SiBr promoted the direct use of enol acetates in the coupling with low-reactive silyl ethers, in which functional groups including ketones and aldehydes survived. Sterically hindered silyl ethers such as ROSiEt3, ROSiPh3, ROSit-BuMe2, and ROSii-Pr3 were also applicable.
InI3/me3sii-catalyzed direct alkylation of enol acetates using alkyl acetates or alkyl ethers
Onishi, Yoshiharu,Nishimoto, Yoshihiro,Yasuda, Makoto,Baba, Akio
supporting information; experimental part, p. 1223 - 1225 (2011/11/29)
A combined Lewis acid of InI3 and Me3SiI was used to catalyze the direct coupling reactions of enol acetates with alkyl acetates or alkyl ethers without generating metal waste. The easily-handled alkylating reagents enlarged the application area of this coupling reaction. 2011 The Chemical Society of Japan.
Titanium silicates as efficient catalyst for alkylation and acylation of silyl enol ethers under liquid-phase conditions
Sasidharan, Manickam,Bhaumik, Asim
experimental part, p. 87 - 93 (2011/10/12)
The activity of titanium- and tin-silicate samples such as TS-1, TS-2, Ti-β and Sn-MFI has been investigated for acylation and alkylation of silyl enol ethers under mild liquid-phase conditions. Silyl enol ethers successfully react with acetyl chloride and tert-butyl chloride under dry conditions in the presence of above catalysts to produce the corresponding acylated and alkylated products, respectively. In the case of acetylation reaction, two different nucleophiles with carbon-center (C-atom) and oxygen-center (O-atom) in silyloxy group of silyl enol ether reacts with acetyl chloride to give 1,3-diketone and ketene-ester, respectively. The selectivity for alkylation is always ca. 100% and no side products are formed. Among the various solvents investigated, anhydrous THF was found to be the suitable solvent for alkylation; whereas dichloromethane exhibited high selectivity for diketones for acylation. The formation of nucleophiles from silyl enol ethers appears to be the key step for successful acetylation and tert-butylation by nucleophilic reaction mechanism. Sn-MFI showed less activity than that observed over the titanosilicates. The observed catalytic activity is explained on the basis of "oxophilic Lewis acidity" of titanium silicate molecular sieves in the absence of H 2O under dry reaction conditions.
