- 1,5,7-Triazabicyclo[4.4.0]dec-5-ene Enhances Activity of Peroxide Intermediates in Phosphine-Free α-Hydroxylation of Ketones
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The critical role of double hydrogen bonds was addressed for the aerobic α-hydroxylation of ketones catalyzed by 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD), in the absence of either a metal catalyst or phosphine reductant. Experimental and theoretical investigations were performed to study the mechanism. In addition to initiating the reaction by proton abstraction, a more important role of TBD was revealed, that is, to enhance the oxidizing ability of peroxide intermediates, allowing DMSO to be used rather than commonly used phosphine reductants. Further characterizations with nuclear Overhauser effect spectroscopy (NOESY) confirmed the presence of double hydrogen bonds between TBD and the ketone, and kinetic studies suggested the attack of dioxygen on the TBD-enol adduct to be the rate-determining step. This work should encourage the application of TBD as a catalyst for oxidations.
- Wang, Yongtao,Lu, Rui,Yao, Jia,Li, Haoran
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supporting information
p. 6631 - 6638
(2021/02/05)
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- Oxidation of Vicinal Diols to α-Hydroxy Ketones with H2O2 and a Simple Manganese Catalyst
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α-Hydroxy ketones are valuable synthons in organic chemistry. Here we show that oxidation of vic-diols to α-hydroxy ketones with H2O2 can be achieved with an in situ prepared catalyst based on manganese salts and pyridine-2-carboxylic acid. Furthermore the same catalyst is effective in alkene epoxidation, and it is shown that alkene oxidation with the MnII catalyst and H2O2 followed by Lewis acid ring opening of the epoxide and subsequent oxidation of the alkene to α-hydroxy ketones can be achieved under mild (ambient) conditions.
- Mecozzi, Francesco,Dong, Jia Jia,Saisaha, Pattama,Browne, Wesley R.
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supporting information
p. 6919 - 6925
(2017/12/26)
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- Improved methods for thermal rearrangement of alicyclic α-hydroxyimines to α-aminoketones: Synthesis of ketamine analogues as antisepsis candidates
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Ketamine is an analgesic/anesthetic drug, which, in combination with other drugs, has been used as anesthetic for over 40 years. Ketamine induces its analgesic activities by blocking the N-methyl-D-aspartate (NMDA) receptor in the central nervous system (CNS). We have reported that low doses of ketamine administrated to patients before incision significantly reduced post-operative inflammation as reflected by reduced interleukin-6 (IL-6) sera-levels. Our data demonstrated in a rat model of Gram-negative bacterial-sepsis that if we inject a low dose of ketamine following bacterial inoculation we reduce mortality from approximately 75% to 25%. Similar to what we have observed in operated patients, the levels of TNF-α and IL-6 in ketamine-treated rats were significantly lower than in septic animals not treated with ketamine. On the base of these results, we have designed and synthesized series of new analogues of ketamine applying a thermal rearrangement of alicyclic α-hydroxyimines to α-aminoketones in parallel arrays. One of the analogues (compound 6e) displayed high activity in down-regulating the levels of IL-6 and TNF-α in vivo as compared to ketamine.
- Elhawi, Hagit,Eini, Hadar,Douvdevani, Amos,Byk, Gerardo
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p. 6784 - 6807
(2012/09/07)
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- Thiazol-2-ylidene catalysis in intramolecular crossed aldehyde-ketone benzoin reactions
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Intramolecular crossed aldehyde-ketone benzoin-type reactions catalyzed by nucleophilic carbenes, easily generated from commercially available thiazolium salts as precatalysts, are described. Five- and six-membered cyclic acyloins are obtained in moderate to good yields. Depending on the structure of the aldehyde-ketone substrate, an interchange of the alcohol and ketone function of the resulting acyloin is possible. Simple aldehyde-ketones are not good substrates due to the competing intermolecular reaction. Starting from biphenyl-2,2′-dicarbaldehyde, the intermediate acyloin is converted to 9,10-phenanthrenequinone by mild air oxidation.
- Enders, Dieter,Niemeier, Oliver
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p. 2111 - 2114
(2007/10/03)
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- Asymmetric catalysis. Part 153: Metal-catalysed enantioselective α-ketol rearrangement
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Promoted by catalytic amounts of Ni complexes tertiary α-hydroxyketones 1a, 3a-5a undergo rearrangement, forming chiral isomers 1b, 3b-5b. The best enantioselection was obtained with the model system 1-benzoylcyclopentanol 4a/2-hydroxy-2-phenylcyclohexanone 4b. In a ligand screening 2-[4-(S)-tert-butyloxazolin-2-yl]pyridine gave the highest enantiomeric excess of 46% (S)-4b. The analogous isomerisation reactions of α-hydroxyimines 6a, 7a forming chiral α-aminoketones 6b, 7b were established.
- Brunner, Henri,Kagan, Henri B.,Kreutzer, Georg
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p. 2177 - 2187
(2007/10/03)
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- Direct conversion of tert-β-bromo alcohols to ketones with zinc sulfide and DMSO
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tert-β-Bromo alcohols, derived from simple monoterpene hydrocarbons, react with zinc sulfide in dimethyl sulfoxide to afford saturated ketones as the major and hydroxy ketones as the minor products. The reaction involves initial nucleophilic attack by DMSO on the carbon attached to the halogen, which is assisted by electrophilic zinc sulfide. Subsequent Kornblum type oxidation yields the α-hydroxy ketone. On the other hand, abstraction of proton β to the hydroxyl group followed by an attack of the neighboring hydroxyl moiety on the sulfur of the dimethylsulfoxonium intermediate and its subsequent collapse yields an enol, which tautomerizes to a saturated ketone. The latter pathway is predominantly followed.
- Bettadaiah,Gurudutt,Srinivas
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p. 2460 - 2462
(2007/10/03)
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- Directive effect of the 2- and 3-axial hydroxy groups that appeared in the complex metal hydride reduction of cyclohexanones
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A directive effect of the 2-axial hydroxy group appeared in the LiAlH4, NaBH4, and Zn(BH4)2 reduction of cyclohexanone, while the 3-axial hydroxy group exhibited a steric hindrance. The distance between the carbonyl carbon and the hydroxy group interacting with the hydride reagent was responsible for such a difference. In the reduction of Na[B(OAc)3H], the 2- and 3-axial hydroxycyclohexanones gave the products obtained by the hydride approaching from the side of the hydroxy group. The key point of the stereoselectivity was the formation of Na[B(OAc)2(OR)H, which was more reactive than the parent hydride, by exchanging the acetate ion with the alkoxide. Although the reduction was performed under the condition that the hydride/substrate ratio was 1, the conversion of the hydroxy ketone to an alcohol were 4, NaBH4, and Zn(BH4)2 reductions in tetrahydrofuran. The conversions in the NaBH4 reduction in ethanol were > 90%.
- Senda,Kikuchi,Inui,Itoh
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p. 237 - 242
(2007/10/03)
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- The Cp2TiPh-mediated reductive radical cyclization of cyanoketones and related reactions. Efficient trapping of ketyl radicals by Cp2TiPh- coordinated polar multiple bonds
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The reductive radical cyclization of cyanoketones was achieved using Cp2TiPh. The Ti(III) reagent was prepared by the sequential addition of i- PrMgCl and PhMgBr to commercial Cp2TiCl2 in this order and used effectively without isolation. The cyclization of the γ- and δ-cyanoketones was performed in toluene at ambient temperature for several hours to give α- hydroxycyclopentanones and hexanones in moderate to good yields, respectively. The titanium reagent independently coordinates to both the carbonyl and cyano termini. As a result of lowering the LUMO of the cyano group upon coordination of the Ti(III) species, the irreversible cyclization successfully proceeds without formation of the unstable iminyl radical intermediate. The ester group can also be activated by the coordination of Cp2TiPh, and aromatic ketones with an ester group at the γ position are cyclized to give the corresponding α-hydroxyketones.
- Yamamoto, Yoshihiko,Matsumi, Daisuke,Hattori, Reiko,Itoh, Kenji
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p. 3224 - 3229
(2007/10/03)
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- Cp2TiPh-coordinated cyano and ester groups as efficient ketyl radical acceptors in the reductive radical cyclization of γ- And δ-cyano ketones and δ-keto esters
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Cp2TiPh promotes the reductive radical cyclization of γ-and δ-cyano ketones and δketo esters to give α-hydroxycycloalkanones in moderate to good yields; the titanium reagent coordinates to both the ketone and the cyano or ester terminus, the LU
- Yamamoto, Yoshihiko,Matsumi, Daisuke,Itoh, Kenji
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p. 875 - 876
(2007/10/03)
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- Catalytic dihydroxylation of methylcyclohexene isomers in the presence of bromine-containing molybdenum compounds
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An investigation has been made of the kinetic relationships governing the dihydroxylation of methylcyclohexene isomers in the presence of Mo(V) and Mo(VI) oxobromides. It was established that the dihydroxylation of cyclo-olefins proceeds both via an intermediate stage of formation of the corresponding epoxy compound and directly from the cyclo-olefin by breakdown of the peroxy complex. Kinetic equations have been derived, and a kinetic model of the process has been constructed which describes the main routes of the reaction.
- Alimardanov,Akhundova,Veliyeva,Aliyev
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p. 445 - 454
(2007/10/03)
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- Selective oxidation of O-isopropylidene derivatives of diols to 2-hydroxy ketones employing dioxiranes
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Employing dimethyldioxirane (1a) or methyl(trifluoromethyl)dioxirane (1b), the direct conversion of O-isopropylidene derivatives of 1,2-diols into the corresponding 2-hydroxy ketones can be achieved in high yield and under mild conditions; optically active acetonides are transformed into homochiral 2-hydroxy ketones in high optical yield, and with preservation of configuration at the C*-OH chiral center proximal to that undergoing oxidation to carbonyl. The diacetonide of 1,4-Diphenylbutan-1,2:3,4-tetraol could be selectively converted into 1,4-diphenyl-1-oxo-2-hydroxy 3,4-acetonide, with removal of just one acetonide moiety.
- Curci, Ruggero,D'Accolti, Lucia,Dinoi, Anna,Fusco, Caterina,Rosa, Angela
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p. 115 - 118
(2007/10/02)
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- Oxidation reactions catalysed by titanium- and chromium-containing silicalites
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While the titanium silicalite-1 (TS-1)-tert-butyl hydroperoxide (TBHP) combination exhibits remarkable activity and selectivity in the oxidative cleavage of the C-C double bond of silyl enol ethers to produce dicarboxylic acids, the chemoselective oxidation of thioethers to sulfoxides without generation of sulfones is achieved using chromium silicalite-2 (CrS-2)-H2O2.
- Raju, Satya V. N.,Upadhya,Ponrathnam,Daniel,Sudalai
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p. 1969 - 1970
(2007/10/03)
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- Ruthenium-Catalyzed Oxidative Transformation of Alkenes to α-Ketols with Peracetic Acid. Simple Synthesis of Cortisone Acetate
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The reactions of alkenes with peracetic acid in the presence of RuCl3 catalyst gave the corresponding α-ketols, which are important building units for synthesis of biological active compounds, such as cortisone acetate.
- Murahashi, Shun-Ichi,Saito, Takao,Hanaoka, Hidenori,Murakami, Yoshihide,Naota, Takeshi,et al.
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p. 2929 - 2930
(2007/10/02)
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- Process for producing α-hydroxyketones
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A process for producing an α-hydroxyketone represented by formula (I): STR1 wherein R1 represents a substituted or unsubstituted alkyl group, a substituted or unsubstituted aralkyl group, or an alkoxycarbonyl group; and R2 and R3 each represent a hydrogen atom, a substituted or unsubstituted alkyl group, or a substituted or unsubstituted aralkyl group, provided that they do not simultaneously represent a hydrogen atom; or a pair of R1 and R2, a pair of R1 and R3, or a pair of R2 and R3 is taken together to form a ring; and the pair of R1 and R2 and the pair of R2 and R3 may form a ring simultaneously, is disclosed, comprising reacting a compound represented by formula (II): STR2 wherein R1, R2, and R3 are as defined above, with an oxidizing agent in the presence of a ruthenium compound and water. α-Hydroxyketones useful as physiologically active substances are produced with good selectivity and in high yield.
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- Electroorganic Chemistry. 140. Electroreductively Intra- and Intermolecular Couplings of Ketones with Nitriles
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Electroreduction of γ- and δ-cyano ketones in i-PrOH with Sn cathode gave α-hydroxy ketones and their dehydroxylated ketones as the intramolecularly coupled products.Guaiazulene, (-)-valeranone, polyquinanes, dihydrojasmone, methyl dihydrojasmonate, and rosaprostol have been synthesized by utilizing this electroreductive intramolecular coupling of γ- and δ-cyano ketones in one of the key steps.Similarly, electroreduction of a mixture of ketone and nitrile gave the corresponding intermolecularly coupled product.The product obtained by the electroreductive intermolecular coupling of (+)-dihydrocarvone with acetonitrile has been found to be the precursor of an effective chiral ligand for the enantioselective addition of diethylzinc to aldehydes.
- Shono, Tatsuya,Kise, Naoki,Fujimoto, Taku,Tominaga, Naoto,Morita, Hiroshi
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p. 7175 - 7187
(2007/10/02)
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- Cobalt(II) Complex Catalyzed Epoxidation of Olefins by Combined Use of Molecular Oxygen and Cyclic Ketones
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In the presence of a catalytic amount of cobalt(II)-Schiff base complexes, various olefins are smoothly oxygenated into the corresponding epoxides in good to high yields by combined use of an atmospheric pressure of oxygen (oxidant) and cyclic ketones (reductant), such as 2-methylcyclohexanone, under mild conditions.
- Takai, Toshihiro,Hata, Eiichiro,Yorozu, Kiyotaka,Mukaiyama, Teruaki
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p. 2077 - 2080
(2007/10/02)
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- ELECTROREDUCTIVE INTRAMOLECULAR COUPLING OF γ- AND δ-CYANOKETONES
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Electroreduction of γ- and δ-cyanoketones in i-PrOH gave cyclized products α-hydroxyketones and their dehydroxylated ketones, and this reaction was applied to the synthesis of dihydrojasmone, methyl dihydrojasmonate, and Rosaprostol.
- Shono, Tatsuya,Kise, Naoki
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p. 1303 - 1306
(2007/10/02)
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- α-Oxidation of ketones using n-cation radicals
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Six-membered ring ketones and acyclic ketones were oxidized by stable triarylamminium radical cations in moist acetonitrile at room temperature in the presence of a base to α-hydroxy ketones in good yield. Five-membered ring ketones gave the corresponding αβ-unsaturated compounds.
- Schulz, Manfred,Kluge, Ralph,Sivilai, Li,Kamm, Birgit
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p. 2371 - 2380
(2007/10/02)
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- Synthesis of Trimethylsilyloxy and Hydroxy Compounds from Carbanions and Bis(trimethylsilyl)peroxide.
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The reactions of bis(trimethylsilyl)peroxide with alkyl, vinyl, alkynyl, aromatic and heteroaromatic anions are described.Depending on the reaction conditions, the trimethylsilyloxy derivatives can be obtained alone or together with the corresponding trimethylsilyl derivatives, which is sometimes the major product.Enolates, generated using magnesium diisopropylamide give the corresponding hydroxycarbonyl compounds in good yields.An attempt to rationalise the above results is given, emphasising the wide use of bis(trimethylsilyl)peroxide in organic synthesis as an electrophilic hydroxylation reagent.
- Camici, Lucia,Dembech, Pasquale,Ricci, Alfredo,Seconi, Giancarlo,Taddei, Maurizio
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p. 4197 - 4206
(2007/10/02)
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- DIASTEREOFACE-DIFERENTIATING ADDITION OF ORGANOMETALLICS TOWARD CHIRAL α-KETOENAMINES
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The diastereoface-differentiating reaction of Grignard reagents or organolithium reagents toward chiral cyclic α-ketoenamines, prepared from the corresponding cycloalkane-1,2-dione and optically active pyrrolidine derivatives, was found to give, after hydrolysis, (R)- or (S)-α-hydroxycycloalkanones, respectively, in high enantiomeric excess.
- Fujisawa, Tamotsu,Watanabe, Makoto,Sato, Toshio
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p. 2055 - 2058
(2007/10/02)
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- α-Hydroxylation on Ketones Using o-Iodosylbenzoic Acid
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o-Iodosylbenzoic acid (KOH/CH3OH) converts various ketones to α-hydroxydimethylacetals in high yield with the advantageous feature of solubility of the reduction product o-iodobenzoic acid under the basic reaction conditions thus allowing isolation of the oxidation product by simple CH2Cl2 extraction.
- Moriarty, Robert M.,Hou, Kwang-Chung
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p. 691 - 694
(2007/10/02)
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- FACILE PREPARATION OF 2,6-DIMETHYL-2,6-TETRAHYDROPYRANCARBOLACTONE, A VERSATILE INTERMEDIATE FOR THE SYNTHESES OF (+/-)-FRONTALIN, (+/-)-CINENIC ACID, AND (+/-)-LINALOYL OXIDE
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2,6-Dimethylcyclohexanone has been converted via its 2,6-dihydroxy derivative by base-catalyzed oxygenation to 2,6-dimethyl-2,6-tetrahydropyrancarbolactone which can be used as a key intermediate for the syntheses of the title natural products in racemic forms.
- Utaka, Masanori,Makino, Hiroshi,Oota, Yukito,Tsuboi, Sadao,Takeda, Akira
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p. 2567 - 2570
(2007/10/02)
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- THE REACTION OF CHROMYL CHLORIDE AND O-SILYLATED ENOLATES: A NOVEL REGIOSPECIFIC ROUTE TO α-HYDROXY KETONES.
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Chromyl chloride reacts regiospecifically with O-silylated enolates to form α-hydroxy ketones.
- Lee, Thomas V.,Toczek, Judy
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p. 2917 - 2920
(2007/10/02)
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- ACTION DE L'OZONE SUR DES DERIVES VINYLIQUES; REACTIONS CONSERVANT L'ENCHAINEMENT CARBONE.
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Ozone reacts with vinyl derivatives (sulphides, enamines, ethers) and gives abnormal reactions or/and double bond cleavages.
- Strobel, Marie-Paule,Morin, Luc,Paquer, Daniel
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p. 523 - 524
(2007/10/02)
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- Sensitized Photooxygenation of Silyl Enol Ethers of Cyclic Ketones
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α,β-Unsaturated and α-hydroxy ketones are accessible in prototropic ene-reactions with singlet oxygen by sensitized photooxygenation of cyclic silyl enol ethers and subsequent reduction and solvolysis.In a competing silatropic ene-reaction α-silyloxyketones are formed.Formation of different products depends on ring size, configuration and substitution.At C-6 chirally substituted 2-cyclohexenones are synthesized for the first time by sensitized photooxygenation of chiral silyl enol ethers of optically active starting ketones.
- Friedrich, Edgar,Lutz, Werner
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p. 1245 - 1263
(2007/10/02)
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