69814-25-1Relevant academic research and scientific papers
α- And β-Functionalized Ketones from 1,3-Dienes and Aldehydes: Control of Regio- And Enantioselectivity in Hydroacylation of 1,3-Dienes
Parsutkar, Mahesh M.,Rajanbabu, T. V.
supporting information, p. 12825 - 12835 (2021/08/30)
Ketones are among the most widely used intermediates in organic synthesis, and their synthesis from inexpensive feedstocks could be quite impactful. Regio- and enantioselective hydroacylation reactions of dienes provide facile entry into useful ketone-bearing chiral motifs with an additional latent functionality (alkene) suitable for further elaboration. Three classes of dienes, 2- or 4-monosubstituted and 2,4-disubstituted 1,3-dienes, undergo cobalt(I)-catalyzed regio- and enantioselective hydroacylation, giving products with high enantiomeric ratios (er). These reactions are highly dependent on the ligands, and we have identified the most useful ligands and reaction conditions for each class of dienes. 2-Substituted and 2,4-disubstituted dienes predominantly undergo 1,2-addition, whereas 4-substituted terminal dienes give highly enantioselective 4,1- or 4,3-hydroacylation depending on the aldehyde, aliphatic aldehydes giving 4,1-addition and aromatic aldehydes giving 4,3-addition. Included among the substrates are feedstock dienes, isoprene (US$1.4/kg) and myrcene (US$129/kg), and several common aldehydes. We propose an oxidative dimerization mechanism that involves a Co(I)/Co(III) redox cycle that appears to be initiated by a cationic Co(I) intermediate. Studies of reactions using isolated neutral and cationic Co(I) complexes confirm the critical role of the cationic intermediates in these reactions. Enantioselective 1,2-hydroacylation of 2-trimethylsiloxy-1,3-diene reveals a hitherto undisclosed route to chiral siloxy-protected aldols. Finally, facile syntheses of the anti-inflammatory drug (S)-Flobufen (2 steps, 92% yield, >99:1 er) and the food additive (S)-Dihydrotagetone (1 step, 83% yield; 96:4 er) from isoprene illustrate the power of this method for the preparation of commercially relevant compounds.
gamma-alkenyl ketone and preparation method thereof
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Paragraph 0207-0211, (2020/02/29)
The invention discloses a gamma-alkenyl ketone preparation method, wherein the target product can be obtained at high yield and high regioselectivity by using acetophenone and 1,3-butadiene as raw materials in the presence of an organic solvent, a catalyst, an additive and a ligand. According to the invention, the method has advantages of high atom economy, high regioselectivity, high yield and the like, can achieve the efficient conversion from a cheap basic organic chemical product 1,3-butadiene to high-added-value gamma-alkenyl ketone, and uses the cheap catalyst, so that the reaction conditions are neutral and mild, and the experimental operation is safe and simple; and the synthesized gamma-alkenyl ketone is a useful synthetic intermediate, can be subjected to a series of conversionsto obtain a series of drug molecule precursors or key intermediates, and has wide application prospect.
Organocatalytic Redox Isomerization of Electron-Deficient Allylic Alcohols: Synthesis of 1,4-Ketoaldehydes
Mondal, Keshab,Mondal, Buddhadeb,Pan, Subhas Chandra
, p. 4835 - 4840 (2016/07/06)
An organocatalytic redox isomerization strategy has been developed for the synthesis of 1,4-ketoaldehydes. DABCO was found to be the best catalyst for the isomerization of -hydroxy enones. With 20 mol % of DABCO as catalyst and DMSO as the solvent high yi
Catalytic activation of carbohydrates as formaldehyde equivalents for stetter reaction with enones
Zhang, Junmin,Xing, Chong,Tiwari, Bhoopendra,Chi, Yonggui Robin
supporting information, p. 8113 - 8116 (2013/07/19)
We disclose the first catalytic activation of carbohydrates as formaldehyde equivalents to generate acyl anions as one-carbon nucleophilic units for a Stetter reaction. The activation involves N-heterocyclic carbene (NHC)-catalyzed C-C bond cleavage of carbohydrates via a retro-benzoin-type process to generate the acyl anion intermediates. This Stetter reaction constitutes the first success in generating formal formaldehyde-derived acyl anions as one-carbon nucleophiles for non-self-benzoin processes. The renewable nature of carbohydrates, accessible from biomass, further highlights the practical potential of this fundamentally interesting catalytic activation.
The cascade carbo-carbonylation of unactivated alkenes catalyzed by an organocatalyst and a transition metal catalyst: A facile approach to γ-diketones and γ-carbonyl aldehydes from arylalkenes under air
Xie, Jin,Huang, Zhi-Zhen
supporting information; experimental part, p. 1947 - 1949 (2010/06/21)
A novel cascade carbo-carbonylation reaction of unactivated arylalkenes with ketones or aldehydes was catalyzed by an organocatalyst and a transition metal catalyst via a SOMO-enamine under air, affording a simple approach to γ-diketones and γ-carbonyl aldehydes. The Royal Society of Chemistry 2010.
Neighboring group participation in Lewis acid-promoted [3 + 4] and [3 + 5] annulations. The synthesis of oxabicyclo[3.n.1]alkan-3-ones
Molander, Gary A.,Camera, Kimberly O.
, p. 830 - 846 (2007/10/02)
Lewis acids are employed as catalysts in the annulation of 1,4- and 1,5-dicarbonyl dielectrophiles with bis(trimethylsilyl) end ethers of β-diketones and β-keto esters. A variety of 2-(alkoxycarbonyl)-m-oxabicyclo[3.n.1]alkan-3-ones can be constructed by this process in which two new carbon-carbon bonds are generated. Unusually high regiocontrol is observed, and good to excellent stereochemical control can be achieved at virtually every position on the new carbocycles. Intramolecular neighboring group participation is proposed to explain the unusually high selectivities attained in the annulation reaction.
Transition Metal- and Acid-Induced Transformations of 6-Siloxy-Substituted 5,6-Dihydro-4H-1,2-oxazines: Preparation of Pyrroles, Nitrones, 1,4-Dicarbonyl Compounds and Derivatives Thereof
Hippeli, Claudia,Zimmer, Reinhold,Reissig, Hans-Ulrich
, p. 469 - 474 (2007/10/02)
A variety of 6-siloxy-substituted 5,6-dihydro-4H-1,2-oxazines (abbreviation: 1,2-oxazines) 1, 3 could be transformed into di- and trisubstituted pyrroles 2, 4 by means of molybdenum hexacarbonyl.The mechanism of this deoxygenating ring contraction is discussed.With two bicyclic 1,2-oxazines an acid-catalyzed fragmentation affording α-methylenecycloalkanones 7 has been observed, while other 1,2-oxazines rearrange in methanolic acid to give nitrones 9, 10.The desilylation of 6-siloxy-substituted 1,2-oxazines 1.3 employing NEt3*3HF is a very general and smooth process providing 6-hydroxy-1,2-oxazines 11, 12 or their corresponding acyclic tautomers 13, 14 in high yields.For two examples of 11 deoximations by use of formalin could be achieved with moderate efficiency giving 1,4-dicarbonyl compounds 15.
