- Synthesis of Sterically Hindered β-Diketones via Condensation of Acid Chlorides with Enolates
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Bulky β-diketones have rarely exceeded dipivaloylmethane (DPM) in steric demand, largely due to synthetic limitations of the Claisen condensation. This work demonstrates hindered acid chlorides to be selective electrophiles in noncoordinating solvents for condensations with enolates. An improved synthesis of DPM is described (90% yield), and crowded β-diketones featuring bulky o-biphenyl or m-terphenyl fragments were prepared in good to excellent yields. These compounds are anticipated to have a steric profile far greater than that of DPM. General reaction conditions and mechanistic considerations are included.
- Crossman, Aaron S.,Larson, Alec T.,Shi, Jake X.,Krajewski, Sebastian M.,Akturk, Eser S.,Marshak, Michael P.
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- ON THE REACTION OF 2,2,6,6-TETRAMETHYL-3,5-HEPTANEDIONE ("DIPIVALOYLMETHANE") WITH OXALYL CHLORIDE
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Refluxing of dipivaloylmethane (1) in an excess of oxalyl chloride gives a mixture containing the 5-chloro-furanone derivatives (2), (3), and (4), which then can be completely converted into the 5-tert-butyl-4-pivaloylfuran-2,3-dione (5).Compounds (2-5) are hydrolyzed to the carboxylic acid (6), which in reverse is easily recyclized to 5.
- Kollenz, Gert,Kappe, C. Olivier,Nabey, Hesham Abd el
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- AUTOMATIC ASSEMBLY OF SKELETON STRUCTURES. 3. STEREOSELECTIVE SYNTHESIS, STEREOCHEMISTRY, AND CYCLIZATION OF d,l-α,α'-DIOXY-α,α'-DI-tert-BUTYLGLUTARIC ACID
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Stereoselective synthesis of d,l-α,α'-dioxy-α,α'-di-tert-butylglutaric acid hydroxyiminolactonitrile (3) was conducted by the reaction of dipivaloylmethane with HCN in ether.The corresponding hydroxylacetonitrile (4) and amide (5), acid (6), and its ester (7), from which dilactone (8) was synthesized with preparative yields, were obtained from 3.Benzyl amide (9) was obtained by the reaction of 8 with BnNH2.The iminolactone structure 3 of dipivaloylmethane bis-cyanohydrin, the cis-pseudo-a orientation of the functional substituents in 3-7 and 9, and the structureof the dilactone 8 were confirmed by the 1H, 13C NMR, IR and mass spectra.Keywords: stereoselective synthesis, stereochemistry, cyclization, γ-lactone, 1H and 13C NMR, mass spectra.
- Vystorop, I. V.,El'natanov, Yu. N.,Kostyanovskii, R. G.
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- Method for synthesizing 1, 3-dicarbonyl compound based on terminal alkyne and acyl halide by one-pot process
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The invention belongs to the technical field of catalytic synthesis, and discloses a method for synthesizing a 1, 3-dicarbonyl compound by a one-pot process, and the method comprises the following steps: by using simple palladium and copper salts as catalysts, reacting terminal alkyne with acyl halide at 0-80 DEG C for 0.5-12 hours under the action of trifluoromethanesulfonic acid to obtain the 1,3-dicarbonyl compound, wherein the molar ratio of the terminal alkyne to the acyl halide to the palladium salt to the copper salt to the trifluoromethanesulfonic acid is 1 to (1 to 2) to (0.00001 to0.10) to (0.00001 to 0.10) to (0.00004 to 0.40); the catalysts used in the method are common the commercialized palladium salt and copper salt, reagents used in the reaction are commercialized reagents, in addition, the raw materials are cheap and easy to obtain, functional group tolerance is good, reaction conditions are mild, operation is easy and convenient, and atom economy is high.
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Paragraph 0069-0074; 0135-0137
(2020/07/21)
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- Method of preparing 1,3-diketone compound by acetyenic ketone
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The invention relates to a preparation method of preparing a 1,3-diketone compound by acetyenic ketone. The preparation method comprises the following steps: S1, putting alpha-alkynyl ketone compound,water, gold salt and silver salt in a reaction solvent to obtain a precursor mixture, wherein the molar ratio of the alpha-alkynyl ketone compound, water, gold salt and silver salt is 1: (1-50): (0.001-0.10): (0.002-0.15); and S2, putting the precursor mixture obtained in the S1 to react at a reaction temperature of 0-50 DEG C to obtain the 1,3-diketone compound, wherein the reaction time is 5 min to 48 h. The method is simple in reaction condition, free of acid or alkaline additives and high in yield, and can be applied to modern production on a large scale.
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Paragraph 0236-0241
(2019/06/12)
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- Synthesis method of 2,2,6,6-tetramethyl-3,5-heptadione
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The invention discloses a synthesis method of 2,2,6,6-tetramethyl-3,5-heptadione. The synthesis method comprises the following steps: a, material feeding: mixing methyl trimethylacetate, alkali and a solvent, and uniformly stirring for 0.5 to 3 hours to obtain a mixed solution; b, reaction: continuously stirring the mixed solution in the step a under a heating condition at the temperature of 20 to 60 DEG C, slowly dripping tert-butyl methyl ketone into the mixed solution, and generating reaction at normal pressure for 8 to 48 hours to obtain reaction liquid containing a product; c, purification: adding water into the reaction liquid in the step b, uniformly stirring, and performing purification. Due to the mode, the synthesis method disclosed by the invention is easy to operate, low in cost and favorable for realizing industrialization, and can meet the technological requirement on green chemistry.
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Paragraph 0052-0055
(2017/08/27)
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- Observation of 1,3-diketones formation in the reaction of bulky acyl chlorides with methyllithium
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The formation of 1,3-diketones was observed in the reactions of bulky acyl chlorides with methyllithium. The reaction products depend on the steric hindrance around the carbonyl group of the acyl chloride and the electronic effect of the group(s) linked to the carbonyl. When the steric hindrance around the carbonyl group of the acyl chloride is big enough, the 1,3-diketone is the only product. In the case of the moderate hindrance around the carbonyl group of the acyl chloride, a moderate yield of 1,3-diketone is obtained and some tertiary alcohol is generated. When there is no steric hindrance around the carbonyl group of the acyl chloride, the tertiary alcohol is the only product. When the steric hindrance around the carbonyl group is moderate and an electron-donating group is connected to the carbonyl of the acyl chloride, all three products-ketone, 1,3-diketone and tertiary alcohol-can be isolated from the reaction mixture after long reaction times.
- Zhang, Jian,Yang, Nianfa,Yang, Liwen
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experimental part
p. 6415 - 6423
(2012/09/08)
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- Synthesis of sterically hindered 1,3-diketones
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An efficient and practical method for the synthesis of sterically hindered aliphatic/aromatic 1,3-diketones via coupling of ketones with esters using potassium tert-butoxide is described. The protocol requires milder operating conditions, and the products are obained in good to excellent yields. Copyright Taylor & Francis Group, LLC.
- Nandurkar, Nitin S.,Bhanushali, Mayur J.,Patil, Dinkar S.,Bhanage, Bhalchandra M.
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p. 4111 - 4115
(2008/03/13)
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- Kinetics and mechanism of ligand substitution in β-diketone complexes of iron(III). Solvolysis controlling the substitution process in alcohol media
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Conventional and stopped-flow spectrophotometry was used to study the kinetics of ligand substitution in a number of tris β-diketone iron(III) complexes, Fe(O∩O)3, by 8-hydroxyquinoline (=HO∩N) in alcohol media (O∩O-=anion of the β-diketones pentane-2,4-dione, 2,6-dimethylheptane-3,5-dione, 2,2,6,6-tetramethylheptane-3,5-dione, 1-phenylbutane-1,3-dione, 1,3-diphenylpropane-2,3-dione, and 1-(2-thienyl)-4,4,4-trifluorobutane-1,3-dione). As shown by spectrophotometry, the solutions of complexes Fe(O∩O)3 in alcohols ROH are subject to solvolytic dissociation, leading to solvento species Fe(O∩O)2S2 and to binuclear complexes [Fe(O∩O)2(RO)]2 (S=ROH and RO-, respectively). The reaction of complexes Fe(O∩O)3 with HO∩N in alcohol media, leading to Fe(O∩N)3, is triphasic. The corresponding first-order rate constants k1, k2, and k3 are independent of the concentration of the entering ligand HO∩N and follow the order k1>k2>k3, with k1/k2≈10 and k1/k3≈102. For a given system Fe(O∩O)3/HO∩N/ROH, the size of k1, k2, and k3 correlates with the solvent polarity parameter ET(30). Rate constant k1 describes the solvolytic dissociation of the complexes Fe(O∩O)3 and rate constant k3 the solvent-initiated splitting of the binuclear complexes [Fe(O∩O)2(RO)]2. Rate constant k2 is assigned to the solvolytic dissociation of the intermediate complex Fe(O∩O)2(O∩N). Depending on the nature of the coordinated β-diketone and solvent ROH, k1 ranges from 0.04 to 2 s-1, k2 from 0.007 to 0.2 s-1, and k3 from 0.002 to 0.01 s-1 at 298 K. The mechanism of the ligand substitution processes is discussed.
- Gumbel, Gerhard,Elias, Horst
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- The Crystallographic Characterization of an Unusual Chemical Reversal of Photoisomerization
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Imines formed from pinacolone and primary amines could be acylated by acid chlorides or anhydrides to products hydrolysable to 1,3-diones.Benzoyl chloride with pinacolone benzylimine gave 3-(N-benzoyl-N-benzylamino)-4,4-dimethyl-1-phenylpent-2-en-1-one, both geometrical isomers of which were prepared.The yellow Z isomer was converted into the colourless E isomer on exposure to daylight and this change was reversed by brief treatment of the E isomer with aqueous ethanolic alkali.The Z and E isomers have been characterized crystallographically.The E isomer is monoclinic, C2/c, a 10.241(4), b 17.199(6), c 25.495(9) Angstroem, β 100.45(3) deg, Z = 8; R was 0.052 for 1947 'observed reflections.The Z-isomer is orthorhombic, P212121, a 18.24(1), b 15.60(1), c 7.871(4) Angstroem, Z = 4; R was 0.61 for 902 'observed' reflections.
- Cornforth, John,Patrick, Vincent A.,White, Allan H.
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p. 1453 - 1460
(2007/10/02)
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