- Chelation-controlled intermolecular alkene and alkyne hydroacylation: The utility of β-thioacetal aldehydes
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(Chemical Equation Presented) β-Thioacetal-substituted aldehydes, which are conveniently prepared from the corresponding ynals, can be combined with a range of alkynes or electron-poor alkenes to deliver intermolecular hydroacylation adducts. The reactions employ [Rh(dppe)]ClO4 as a catalyst and are proposed to proceed via a chelated rhodium acyl intermediate. The thioacetal-containing products can be deprotected to the corresponding ketones or reduced to alkanes in good yields.
- Willis, Michael C.,Randell-Sly, Helen E.,Woodward, Robert L.,Currie, Gordon S.
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Read Online
- Photoredox-Catalyzed Isomerization of Highly Substituted Allylic Alcohols by C?H Bond Activation
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Photoredox-catalyzed isomerization of γ-carbonyl-substituted allylic alcohols to their corresponding carbonyl compounds was achieved for the first time by C?H bond activation. This catalytic redox-neutral process resulted in the synthesis of 1,4-dicarbonyl compounds. Notably, allylic alcohols bearing tetrasubstituted olefins can also be transformed into their corresponding carbonyl compounds. Density functional theory calculations show that the carbonyl group at the γ-position of allylic alcohols are beneficial to the formation of their corresponding allylic alcohol radicals with high vertical electron affinity, which contributes to the completion of the photoredox catalytic cycle.
- Guo, Kai,Huang, Jun,Li, Anding,Li, Yuanhe,Yang, Zhen,Zhang, Zhongchao
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supporting information
p. 11660 - 11668
(2020/05/25)
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- An expeditious entry to rare tetrahydroimidazo[1,5-c]pyrrolo[1,2-a]pyrimidin-7(8H)-ones: A single-step gateway synthesis of glochidine congeners
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A single-step gateway synthesis of glochidine and its congeners that possess the rare uncommon tetrahydroimidazo[1,5-c]pyrrolo[1,2-a]pyrimidine core was developed employing histamine and readily available γ-ketoesters. Key features of the developed reaction involve tandem three C–N bonds formation and concomitant annulation of two rings in one pot to access this unique and complex tricyclic structure. Exploration of the unknown bioactivity of these compounds revealed that they elicit antiproliferative activity comparable to the anticancer drug imatinib against 6 cancer cell lines.
- Seo, Jeong Moo,Hassan, Ahmed H.E.,Lee, Yong Sup
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supporting information
(2019/11/26)
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- A synthetic method of chiral gamma-decalactone
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A synthetic method of chiral gamma-decalactone is provided. The method includes steps of (1) adding concentrated sulfuric acid into an organic solvent, then adding a catalyst, a ligand and a phase-transfer catalyst into the mixture, finally adding methyl 4-carbonyldecanoate into the mixture, and reacting the mixture; (2) transferring a reaction product obtained in the step (1) into an autoclave, and filling the autoclave with hydrogen to pressurize the autoclave to 3-6 MPa, with the reaction temperature being 60-120 DEG C and reaction time being 4-8 h; and (3) subjecting a reaction product obtained in the step (2) to neutralization, filtration, solvent recovery and distillation to obtain the chiral gamma-decalactone. The reaction temperature and pressure of the method are proper, and production operation is easy so that the method can be used for industrial production. The ee value of the product can be 95% or above.
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Paragraph 0035
(2017/10/05)
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- Mg(OMe)2 promoted allylic isomerization of γ-hydroxy-α,β-alkenoic esters to synthesize γ-ketone esters
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This work concerns the Mg(OMe)2 promoted allylic isomerization of γ-hydroxy-α,β-alkenoic esters with TMEDA as an additive. The isomerization proceeded under mild conditions and afforded γ-keto esters in high yield (up to 96%) within 2 h. Both (Z)- and (E)-γ-hydroxy-α,β-alkenoic esters were tolerated under the reaction conditions. This transformation involves the in situ formation of a dienolate intermediate from the easily accessible γ-hydroxy-α,β-alkenoic ester. The in situ generated dienolate can react with benzaldehyde and undergo a practical, useful tandem allylic isomerization-Aldol reaction to afford more functionalized compounds.
- Lai, Luhao,Li, A-Ni,Zhou, Jiawei,Guo, Yarong,Lin, Li,Chen, Wei,Wang, Rui
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p. 2185 - 2190
(2017/03/17)
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- Solar light-driven photocatalyzed alkylations. Chemistry on the window ledge
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Tetrabutylammonium decatungstate photocatalysis is effective for the C-H activation of alkanes, aldehydes, ethers and amides and the alkylation of alkenes occurs effectively by merely exposing the solution to the sun in a glass vessel on a window ledge (u
- Protti, Stefano,Ravelli, Davide,Fagnoni, Maurizio,Albini, Angelo
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supporting information; experimental part
p. 7351 - 7353
(2010/06/14)
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- PROCESS FOR PRODUCTION OF SUBSTITUTED CYCLOPENTANONE
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A substituted cyclopentanone represented by the formula (2) can be produced by hydrogenating the double bond in a compound represented by the formula (1) in the presence of a transition metal catalyst by using a carboxylic acid or a specific concentration of a carboxylic acid ester as a solvent. This process can produce a substituted cyclopentanone which is useful as an jasmine-flavored fragrance, an intermediate in the production of the fragrance or the like, in a simple and inexpensive manner at a high cis-form ratio; (1) wherein R1 and R2 represent a substituent having 1 to 8 carbon atoms; and (2) wherein R3 and R4 represent a substituent having 1 to 8 carbon atoms, may be the same as R1 and R2, and may be the same as each other.
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Page/Page column 71-73
(2008/06/13)
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- Acylation of electrophilic olefins through decatungstate-photocatalyzed activation of aldehydes
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(Chemical Equation Presented) With tungsten and lamp: Ketones were prepared by the photocatalytic generation of acyl radicals from aldehydes and trapping them with equimolar amounts of electrophilic alkenes. Photocatalysis with tetrabutylammonium decatungstate is effective also at low temperatures (-20 to -50°C), thus minimizing radical decarbonylation and allowing acylation by highly substituted aldehydes. EWG = electron-withdrawing group.
- Esposti, Silvia,Dondi, Daniele,Fagnoni, Maurizio,Albini, Angelo
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p. 2531 - 2534
(2008/03/11)
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- Rhodium-catalyzed intermolecular chelation controlled alkene and alkyne hydroacylation: Synthetic scope of β-S-substituted aldehyde substrates
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The use of β-S-substituted aldehydes in rhodium-catalyzed intermolecular hydroacylation reactions is reported. Aldehydes substituted with either sulfide or thioacetal groups undergo efficient hydroacylation with a variety of electron-poor alkenes, such as enoates, in Stetter-like processes and with both electron-poor and neutral alkynes. In general, the reactions with electron-poor alkenes demonstrate good selectivity for the linear regioisomer, and the reactions with alkynes provide enone products with excellent selectivity for the E-isomers. The scope of the process was shown to be broad, tolerating a variety of substitution patterns and functional groups on both reaction components. A novel CN-directing effect was shown to be responsible for reversing the regioselectivity in a number of alkyne hydroacylation reactions. Catalyst loadings as low as 0.1 mol % were achievable.
- Willis, Michael C.,Randell-Sly, Helen E.,Woodward, Robert L.,McNally, Steven J.,Currie, Gordon S.
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p. 5291 - 5297
(2007/10/03)
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- 1,2,4-Trioxepanes: Redox-cleavable protection for carbonyl groups
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(Chemical Equation Presented) 1,2,4-trioxepanes, readily prepared and easily handled derivatives of aldehydes and ketones, are stable to a variety of synthetic conditions and yet easily deblocked with Zn/HOAc or Mg/MeOH to regenerate the parent carbonyl. Trioxepanes may provide an alternative to 1,3-dithianes for acid-stable protection of carbonyl groups.
- Ahmed, Aqeel,Dussault, Patrick H.
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p. 3609 - 3611
(2007/10/03)
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- Reactions of Dioxiranes with Selected Oleochemicals
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Reaction of fatty acids with dimethyldioxirane in acetone produces ketoacids in 9-12percent yields in which the ketone carbonyl is distributed along the fatty chain.The n-1 position appears to be preferred.Lactones of hydroxy fatty acids are oxidized by this reagent, but in low yields, to the corresponding ketoacids.Biphasic epoxidations with methylethyldioxirane in 2-butanone were conducted with methyl oleate and methyl ricinoleate to give the corresponding epoxides in high yield, and olive oil and tallow were cleanly epoxidized by this procedure as well.KEY WORDS: Chain functionalization, dioxirane, epoxidation, oleic acid, ricinoleic acid, tallow.
- Sonnet, P. E.,Lankin, M. E.,McNeill, G. P.
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p. 199 - 204
(2007/10/02)
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- A new convenient synthesis of methyl 4-oxoalkanoates
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Methyl 4-oxoalkanoates have been obtained in good yields by treatment of 1,2-dichloro-2-alken-4-ones with sodium carbonate in methanol followed by acid-catalyzed hydrolysis of the intermediate 5-alkyl-2,2-dimethoxy-2,3-dihydrofurans.
- Kulinkovich,Sorokin
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p. 361 - 362
(2007/10/02)
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- Hydroacylation of Alkyl Vinyl Ketones and Acrylic Esters Using Organotetracarbonylferrates. Synthesis of 1,4-Dicarbonyl Compounds
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Alkyl vinyl ketones and acrylic esters were hydroacylated with organotetracarbonylferrates to the corresponding 1,4-diketones and 4-oxo carboxylic acid derivatives in good yield in dipolar aprotic solvents such as N,N-dimethylacetamide.Addition of 18-crown-6 improved the yield. cis-Jasmone and γ-jasmolactone were synthesized by use of these reactions.
- Yamashita, Masakazu,Tashika, Haruyoshi,Uchida, Masaya
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p. 1257 - 1261
(2007/10/02)
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- Double Alkylation of Carbon Monoxide via Free Radicals: Synthesis of Unsymmetrical Ketones
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A novel method for the synthesis of unsymmetrical ketones via the free radical carbonylation of alkyl halides is described.The mechanism of the reaction involves the trapping of an alkyl free radical by CO, the addition of the acyl free radical so formed to an alkene, and termination of the reaction by the abstraction of a hydrogen atom from tributyltin hydride by the product acyl-substituted free radical.
- Ryu, Ilhyong,Kusano, Kazuya,Yamazaki, Hiroshi,Sonoda, Noboru
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p. 5003 - 5005
(2007/10/02)
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- FACTORS GOVERNING PRODUCT DISTRIBUTION IN THE OXIDATION OF ALKENES BY MANGANESE(III) ACETATE IN ACETIC ACID AND ACETIC ANHYDRIDE
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A systematic investigation has been carried out into the effect of different reaction parameters on the oxidation of oct-1-ene by manganese(III) acetate in acetic acid and acetic anhydride.The most important factor in dictating the ratio of products is the composition of the solvent.In the absence of anhydride γ-decanolactone is virtually the sole product.Even small quantitites of anhydride lead to the lactone being replaced by other products derived from cationic intermediates C6H13CH(1+)CH2COX (X = OH or OAc).Further increases in the amount of anhydride encourage the formation of decanoic acid until, in 90percent anhydride, this becomes the predominant product.The results cannot be interpreted simply in terms of competition for the alkene by the radicals (.)CH2CO2H and (.)CH2COOCOCH3.Decanoic acid formation is also favoured by low temperatures, low concentration of oxidants, and by the addition of acetate ions.A comparision is made of the efficiency of addition when the initiating species is manganese(III) or a peroxide.
- Midgley, Gary,Thomas, C. Barry
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p. 1537 - 1544
(2007/10/02)
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- RUTHENIUM HYDRIDE-CATALYZED DOUBLE BOND MIGRATION OF 2,5-DIMETHOXY-2,5-DIHYDROFURANS. A NEW PROCESS FOR THE PREPARATION OF γ-KETOESTERS
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γ-Ketoesters are obtained in excellent yields by means of double bond migration of 2,5-dimethoxy-2,5-dihydrofurans mediated by a ruthenium hydride complex, HRuCl(PPh3)3(C6H5CH3) or HRuCl(CO)(PPh3)3, and subsequent hydrolysis in acidic media.
- Hirai, Kenji,Suzuki, Hiroharu,Kashiwagi, Hiroshi,Moro-Oka, Yoshihiko,Ikawa, Tsuneo
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- REGIOSELECTIVE OXIDATION OF INTERNAL OLEFINS BEARING NEIGHBORING OXYGEN FUNCTIONS BY MEANS OF PALLADIUM CATALYSTS. A DIRECT PREPARATION OF γ-KETO ESTERS AND 1,4-DIKETONES FROM β,γ-UNSATURATED ESTERS AND KETONES
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γ-Keto esters and 1,4-diketones were prepared by the palladium-catalyzed regioselective oxidation of β,γ-unsaturated esters and ketones.The best yields were obtained when the reaction was carried out using PdCl2/CuCl/O2 catalyst system in aqueous dioxane.
- Nagashima, Hideo,Sakai, Kiyomi,Tsuji, Jiro
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p. 859 - 860
(2007/10/02)
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