18448-47-0Relevant articles and documents
Synthesis of α,β-unsaturated ketones and esters using polymer-supported selenium bromide
Sheng, Shou-Ri,Liu, Xiao-Ling,Wang, Xing-Cong
, p. 279 - 281 (2003)
Treatment of the polymer-supported α-phenylseleno ketones and esters prepared from polymer-supported selenium bromide with ketone and ester enolates with hydrogen peroxide afford α,β-unsaturated ketones and esters in good yields and high purities.
Improved Preparation of Methyl 3-Oxo-1-cyclohexene-1-carboxylate and Its Use in the Synthesis of Substituted 1,5-Cyclodecadienes
Lange, Gordon L.,Otulakowski, John A.
, p. 5093 - 5096 (1982)
An improved preparation of methyl 3-oxo-1-cyclohexene-1-carboxylate (6) is reported in which cyclohexanecarboxylic acid is converted to methyl 1-bromocyclohexanecarboxylate by a variation of the Hell-Volhard-Zelinsky reaction and then the bromo ester is dehydrohalogenated with quinoline and the resultant unsaturated ester is oxidized at an allylic position with chromium trioxide in acetic acid and acetic anhydride to give 6.The overall conversion proceeds in 49percent yield, which is a substantial improvement over previous attempts reported for this sequence.Photoadditionof 6 and cyclobutene-1-carboxylic acid yields adduct 8, which after esterification and thermolysis gives the 1,5-cyclodecadiene 12.In addition, reduction of adduct 8 with NaCNBH3 followed by spontaneous lactoniaztion yields 10, which upon thermolysis gives the lactone diene 11.This approach should have applications in the synthesis of germacranolides that have an ester or related carbonyl function on C(14).
Merging Halogen-Atom Transfer (XAT) and Cobalt Catalysis to Override E2-Selectivity in the Elimination of Alkyl Halides: A Mild Route towardcontra-Thermodynamic Olefins
Zhao, Huaibo,McMillan, Alastair J.,Constantin, Timothée,Mykura, Rory C.,Juliá, Fabio,Leonori, Daniele
supporting information, p. 14806 - 14813 (2021/09/18)
We report here a mechanistically distinct tactic to carry E2-type eliminations on alkyl halides. This strategy exploits the interplay of α-aminoalkyl radical-mediated halogen-atom transfer (XAT) with desaturative cobalt catalysis. The methodology is high-yielding, tolerates many functionalities, and was used to access industrially relevant materials. In contrast to thermal E2 eliminations where unsymmetrical substrates give regioisomeric mixtures, this approach enables, by fine-tuning of the electronic and steric properties of the cobalt catalyst, to obtain high olefin positional selectivity. This unprecedented mechanistic feature has allowed access tocontra-thermodynamic olefins, elusive by E2 eliminations.
Electrochemically driven desaturation of carbonyl compounds
Gnaim, Samer,Takahira, Yusuke,Wilke, Henrik R.,Yao, Zhen,Li, Jinjun,Delbrayelle, Dominique,Echeverria, Pierre-Georges,Vantourout, Julien C.,Baran, Phil S.
, p. 367 - 372 (2021/03/31)
Electrochemical techniques have long been heralded for their innate sustainability as efficient methods to achieve redox reactions. Carbonyl desaturation, as a fundamental organic oxidation, is an oft-employed transformation to unlock adjacent reactivity through the formal removal of two hydrogen atoms. To date, the most reliable methods to achieve this seemingly trivial reaction rely on transition metals (Pd or Cu) or stoichiometric reagents based on I, Br, Se or S. Here we report an operationally simple pathway to access such structures from enol silanes and phosphates using electrons as the primary reagent. This electrochemically driven desaturation exhibits a broad scope across an array of carbonyl derivatives, is easily scalable (1–100 g) and can be predictably implemented into synthetic pathways using experimentally or computationally derived NMR shifts. Systematic comparisons to state-of-the-art techniques reveal that this method can uniquely desaturate a wide array of carbonyl groups. Mechanistic interrogation suggests a radical-based reaction pathway. [Figure not available: see fulltext.]
Photoredox/Cobalt Dual-Catalyzed Decarboxylative Elimination of Carboxylic Acids: Development and Mechanistic Insight
Cartwright, Kaitie C.,Joseph, Ebbin,Comadoll, Chelsea G.,Tunge, Jon A.
, p. 12454 - 12471 (2020/09/09)
Recently, dual-catalytic strategies towards the decarboxylative elimination of carboxylic acids have gained attention. Our lab previously reported a photoredox/cobaloxime dual catalytic method that allows the synthesis of enamides and enecarbamates directly from N-acyl amino acids and avoids the use of any stoichiometric reagents. Further development, detailed herein, has improved upon this transformation's utility and further experimentation has provided new insights into the reaction mechanism. These new developments and insights are anticipated to aid in the expansion of photoredox/cobalt dual-catalytic systems.
Cyanide-Free One-Pot Synthesis of Methacrylic Esters from Acetone
Koyama, Minoru,Kawakami, Takafumi,Okazoe, Takashi,Nozaki, Kyoko
, p. 10913 - 10917 (2019/08/02)
Methacrylic esters, represented by methyl methacrylate (MMA), are widely used as commodity chemicals. Here, the one-pot synthesis of methacrylic esters from acetone, a haloform and alcohols in the presence of an organic base is described. Using DBU as the organic base for the reaction of acetone, chloroform and methanol in acetonitrile afforded MMA in 66 % yield. When the solvent was replaced by benzonitrile, the product MMA was successfully purified by distillation. Applicability of this process to various alcohols was also investigated to show ethyl, phenyl, CF3CH2, and n-C6F13CH2CH2 esters were obtained in moderate yields. The use of bromoform instead of chloroform resulted in the improvement of the yield, for example, methyl and n-C6F13CH2CH2 esters up to 81 and 70 %, respectively. The reaction with deuterated starting materials acetone-d6 and MeOH-d4, with DBU in acetonitrile afforded deuterated MMA (MMA-d8) in 70 % yield.
Synthetic method for 3-acetoxy-2-cyclohexenyl-1-one and derivatives thereof
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Paragraph 0019; 0021; 0024, (2019/10/01)
The invention discloses a synthetic method for 3-acetoxy-2-cyclohexenyl-1-one and derivatives thereof. The synthetic method comprises the following steps: (1) reacting a substance as described in thespecification with nitromethane at 110 DEG C to obtain a product I as described in the specification, wherein R in the product I is H or CH3; (2) reacting the product I of the step (1) with sodium nitrite and acetic acid at 37 DEG C to obtain a product II as described in the specification; (3) reacting the product II of the step (2) with methanol and concentrated sulfuric acid at 88 DEG C to obtain a product III as described in the specification; and (4) weighing the product III of the step (3), potassium carbonate, palladium on activated carbon and t-butyl hydroperoxide, adding the weighed materials into dichloromethane, carrying out a reaction at 0 DEG C, and allowing temperature to naturally rise to room temperature so as to obtain a product IV, wherein R in the product IV is H or CH3.The synthetic method of the invention is simpler and more efficient, and has high total yield; the toxicity of reagents used in the preparation is smaller than the toxicity of m-methoxybenzoic acid, thionyl chloride and the like used in the prior art; and the method is low in cost, simple and convenient in separation and purification, applicable to large-scale preparation and capable of realizingindustrial mass production. The synthetic method is applicable as a general synthetic method for 3-acetoxy-2-cyclohexenyl-1-one and 4-substituted derivatives thereof.
Pd-Catalyzed Carbonylation of Vinyl Triflates to Afford α,β-Unsaturated Aldehydes, Esters, and Amides under Mild Conditions
Zhang, Shaoke,Neumann, Helfried,Beller, Matthias
, p. 3528 - 3532 (2019/05/24)
An efficient and general protocol for the synthesis of α,β-unsaturated aldehydes, esters, and amides via carbonylation of vinyl triflates including derivatives of camphor, ketoisophorone, verbenone, and pulegone was developed. Crucial for these transformations is the use of a specific palladium catalyst containing a pyridyl-substituted dtbpx-type ligand. This procedure also allows for an easy access of dicarbonylated products from the corresponding ketones.
A new selective route towards benzoic acid and derivatives from biomass-derived coumalic acid
Pfennig, Toni,Carraher, Jack M.,Chemburkar, Ashwin,Johnson, Robert L.,Anderson, Austin T.,Tessonnier, Jean-Philippe,Neurock, Matthew,Shanks, Brent H.
supporting information, p. 4879 - 4888 (2017/10/23)
The selective production of aromatics from bio-based sources is an area of interest to expand the potential for greener alternatives to petroleum-derived chemicals. A scalable, efficient route to produce bio-based benzoates is demonstrated by carrying out heterogeneous catalytic reactions in non-toxic bio-based solvents at 180°C obtaining yields of up to 100 mol%. This approach extends the 2-pyrone (coumalic acid/methyl coumalate) Diels-Alder platform by utilizing a bioavailable co-reactant ethylene. A detailed investigation using a combination of kinetic experiments, DFT calculations, and multi-dimensional NMR was carried out to determine the detailed reaction network, and the corresponding activation energies for critical steps. Additionally, a series of experiments were conducted to maximize the yields by comparing different solvents, for both coumalic acid and methyl coumalate. Our results show that the choice of solvent was a significant factor when coumalic acid was the reactant (yields 71-92 mol%), while methyl coumalate was only minimally affected by the solvent (yields 95-100 mol%). Interestingly, the reaction network and kinetic analysis showed that the Diels-Alder reactions were not significantly different between coumalic acid and methyl coumalate, with the rate limiting step for both being decarboxylation with an activation barrier of 141 kJ mol-1 compared to 77 kJ mol-1 for the formation of the bicyclic adduct. Finally, the reaction cascade was found to be highly susceptible to by-product formation when as little as 5 vol% water was present in the solvent, which demonstrates that the absence of water is essential for high yielding benzoate production.
Palladium-Catalyzed α,β-Dehydrogenation of Esters and Nitriles
Chen, Yifeng,Romaire, Justin P.,Newhouse, Timothy R.
supporting information, p. 5875 - 5878 (2015/05/27)
A highly practical and general palladium-catalyzed methodology for the α,β-dehydrogenation of esters and nitriles is reported. Generation of a zinc enolate or (cyanoalkyl)zinc species followed by the addition of an allyl oxidant and a palladium catalyst results in synthetically useful yields of α,β-unsaturated esters, lactones, and nitriles. Preliminary mechanistic investigations are consistent with reversible β-hydride elimination and turnover-limiting, propene-forming reductive elimination.
