- Synthesis of Ketones by C?H Functionalization of Aldehydes with Boronic Acids under Transition-Metal-Free Conditions
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A method for the synthesis of ketones from aldehydes and boronic acids via a transition-metal-free C?H functionalization reaction is reported. The method employs nitrosobenzene as a reagent to drive the simultaneous activation of the boronic acid as a boronate and the activation of the C?H bond of the aldehyde as an iminium species that triggers the key C?C bond-forming step via an intramolecular migration from boron to carbon. These findings constitute a practical, scalable, and operationally straightforward method for the synthesis of ketones.
- Roscales, Silvia,Csáky, Aurelio G.
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- Green Protocol for the O-H Insertion of α-Diazoketones with Alcohols and Water Using Ionic Liquid [Bmim]BF4
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α-Diazoketones undergo readily O-H insertion reactions with alcohols and water in hydrophilic [bmim]BF4 ionic liquid in the absence of any acid catalyst to furnish α-alkoxy and α-hydroxy ketones in excellent yields under neutral conditions. The recovered ionic liquid can be easily reused in four to five cycles with consistent in activity. The use of ionic liquid helps to avoid the use of acid catalysts as well as environmentally unfavorable volatile organic solvents.
- Yadav,Reddy,Srinivas
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- Rhodium-Catalyzed Geminal Oxyfluorination and Oxytrifluoro-Methylation of Diazocarbonyl Compounds
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A new reaction for the rhodium-catalyzed geminal-difunctionalization-based fluorination is presented. The substrates are aromatic and aliphatic diazocarbonyl compounds. As the fluorine source a stable and easily accessible benziodoxole reagent was used. A variety of alcohol, phenol, and carboxylic acid reagents were employed to introduce the second functionality. The reaction was extended to trifluoromethylation using a benziodoxolon reagent. The fluorination and trifluoromethylation reactions probably proceed by a rhodium-containing onium ylide type intermediate, which is trapped by either the F or CF3electrophiles.
- Yuan, Weiming,Eriksson, Lars,Szabó, Kálmán J.
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- Arylation of Aldehydes to Directly Form Ketones via Tandem Nickel Catalysis
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A nickel-catalyzed arylation of both aliphatic and aromatic aldehydes proceeds with air-stable (hetero)arylboronic acids, with an exceptionally wide substrate scope. The neutral condition tolerates acidic hydrogen and sensitive polar groups and also preserves α-stereocenters of some chiral aldehydes. Interestingly, this nickel(0) catalysis does not follow common 1,2-insertion of arylmetal species to aldehydes and β-hydrogen elimination.
- Lei, Chuanhu,Zhu, Daoyong,Tangcueco, Vicente Iii Tiu,Zhou, Jianrong Steve
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supporting information
p. 5817 - 5822
(2019/08/26)
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- Silica-supported HClO4 promotes catalytic solvent- and metal-free O-H insertion reactions with diazo compounds
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Solvent-free O-H insertion reactions in the presence of diazo carbonyl compounds were carried-out in very mild conditions. Unlike the traditional metal-catalysed version, employing rhodium acetate dimer, this method uses eco-friendly silica-supported HClO4 as the catalyst. Only 0.3 mol% of this Br?nsted acid catalyst, that can also be recycled several times, is necessary to guarantee very good yields (up to 97%) in the O-H insertion reactions. Reaction set-up is simple and permitted the preparation of forty-three α-hydroxy and α-alkoxy esters/ketones in just 1 h and at room temperature.
- Gallo, Rafael Douglas C.,Burtoloso, Antonio C. B.
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p. 4547 - 4556
(2018/10/17)
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- A NK - 1 receptor antagonists of the preparation method and its intermediate
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The invention relates to a preparation method of an NK-1 receptor antagonist and an intermediate thereof. The invention provides a preparation method of (5S, 8s)-8-{[1-(3, 5-bis-(trifluoromethyl)phenyl)-ethoxy]methyl}-8-phenyl-1, 7-diaza-spiro[4, 5]dec-2-one (formula I compound), which is prepared from a formula II compound, and also provides the formula II compound and a preparation method thereof. The method provided by the invention has the advantages of simple operation, mild reaction condition, high safety factor, little side reaction, high yield and high purity, lowers the production cost and operation risk, and is very suitable for large-scale industrial production. (formula II as shown in the specification).
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Paragraph 0108; 0110
(2018/07/30)
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- Visible Light Photoredox Cross-Coupling of Acyl Chlorides with Potassium Alkoxymethyltrifluoroborates: Synthesis of α-Alkoxyketones
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A visible-light, single-electron-transfer (SET), photoredox cross-coupling for the synthesis of α-alkoxyketones has been developed. In this method, various aliphatic and aromatic acyl chlorides were successfully coupled with structurally diverse potassium
- Amani, Javad,Sodagar, Esmat,Molander, Gary A.
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supporting information
p. 732 - 735
(2016/03/01)
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- A photochemical strategy for lignin degradation at room temperature
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The development of a room-temperature lignin degradation strategy consisting of a chemoselective benzylic oxidation with a recyclable oxidant ([4-AcNH-TEMPO]BF4) and a catalytic reductive C-O bond cleavage utilizing the photocatalyst [Ir(ppy)2(dtbbpy)]PF6 is described. This system was tested on relevant lignin model substrates containing β-O-4 linkages to generate fragmentation products in good to excellent yields.
- Nguyen, John D.,Matsuura, Bryan S.,Stephenson, Corey R. J.
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supporting information
p. 1218 - 1221
(2014/02/14)
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- Organocatalytic C-H bond arylation of aldehydes to bis-heteroaryl ketones
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An organocatalytic aldehyde C-H bond arylation process for the synthesis of complex heteroaryl ketones has been developed. By exploiting the inherent electrophilicity of diaryliodonium salts, we have found that a commercial N-heterocyclic carbene catalyst promotes the union of heteroaryl aldehydes and these heteroaromatic electrophile equivalents in good yields. This straightforward catalytic protocol offers access to ketones bearing a diverse array of arene and heteroarene substituents that can subsequently be converted into molecules displaying structural motifs commonly found in medicinal agents.
- Toh, Qiao Yan,McNally, Andrew,Vera, Silvia,Erdmann, Nico,Gaunt, Matthew J.
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supporting information
p. 3772 - 3775
(2013/04/24)
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- Copper(I)-catalyzed asymmetric desymmetrization: Synthesis of five-membered-ring compounds containing all-carbon quaternary stereocenters
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A highly stereoselective catalytic alkylation sequence for the synthesis of highly functionalized and versatile five-membered-ring compounds bearing all-carbon quaternary stereocenters was developed. Enantioselective desymmetrization of achiral cyclopentene-1,3-diones was thus executed by chiral Cu-phosphoramidite catalysts. A variety of complicated cyclopentane derivatives can be synthesized with excellent stereoselectivities using a low catalyst loading in a one-pot operation.
- Aikawa, Kohsuke,Okamoto, Tatsuya,Mikami, Koichi
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p. 10329 - 10332
(2012/07/30)
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- [3,3]-sigmatropic rearrangement/5-exo-dig cyclization reactions of benzyl alkynyl ethers: Synthesis of substituted 2-indanones and indenes
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Substituted benzyl alkynyl ethers, prepared from the corresponding α-alkoxy ketones in a two-step sequence involving enol triflate formation and KOtBu-induced E2 elimination, undergo [3,3]-sigmatropic rearrangement/ intramolecular 5-exo-dig cyclization at 60 °C to form substituted 2-indanones in good overall yields. 1,3-cis-Disubstituted-2-indanones are formed preferentially when the benzylic substituent R1 is bulky. Substituted indenes may be prepared from 2-indanones in high yields by Horner-Wadsworth-Emmons reaction.
- Tudjarian, Armen A.,Minehan, Thomas G.
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supporting information; experimental part
p. 3576 - 3581
(2011/06/25)
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- Synthesis of alkynyl ethers and low-temperature sigmatropic rearrangement of allyl and benzyl alkynyl ethers
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(Chemical Equation Presented) α-Alkoxy ketones 3 can be transformed into 1-alkynyl ethers 5 by a two-step procedure involving formation of the enol triflate or phosphate and base-induced elimination. Performing the same reaction sequence with allylic alcohols (R2OH, R2 = allyl) furnishes instead γ,δ-unsaturated carboxylic acid derivatives 6, derived from [3,3]-sigmatropic rearrangement of the intermediate allyl alkynyl ethers at -78 °C and trapping of the subsequently formed ketene with nucleophiles (Nu-H). Benzyl alkynyl ether 5 (R2 = benzyl) rearranges to indanone 7 upon heating to 60 °C.
- Sosa, Juan R.,Tudjarian, Armen A.,Minehan, Thomas G.
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supporting information; experimental part
p. 5091 - 5094
(2009/05/31)
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- Asymmetric phase-transfer catalyzed glycolate alkylation, investigation of the scope, and application to the synthesis of (-)-ragaglitazar
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Asymmetric glycolate alkylation using a protected acetophenone surrogate under solid-liquid phase-transfer conditions is a new approach to the synthesis of 2-hydroxy esters and acids. Diphenylmethyloxy-2,5-dimethoxyacetophenone 1 with a trifluorobenzyl ci
- Andrus, Merritt B.,Hicken, Erik J.,Stephens, Jeffrey C.,Karl Bedke
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p. 9470 - 9479
(2007/10/03)
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- 4-6-Diphenyl pyridine derivatives as antiinflammatory agents
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4-aryl pyrimidine compounds of general formula and salts thereof: wherein X is CH or N; R1 is hydrogen, halogen, C1-6 alkyl, C1-6 alkoxy, etc.; R2 is hydrogen or hydroxy; R3 is hydrogen, C1-6 alkyl, etc.; R4 is hydrogen, hydroxy, halogen, amino, etc.; R5
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- Catalytic, asymmetric Mannich-type reactions of N-acylimino esters: Reactivity, diastereo- and enantioselectivity, and application to synthesis of N-acylated amino acid derivatives
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In the presence of a catalytic amount of Cu(OTf)2-chiral diamine 3e complex, N-acylimino esters reacted with silyl enol ethers to afford the corresponding Mannich-type adducts in high yields with high enantioselectivities. A wide variety of silyl enol ethers derived from ketones, as well as esters and thioesters, reacted smoothly. In the reactions of α-substituted silyl enol ethers (α-methyl or benzyloxy), the desired syn-adducts were obtained in high yields with high diastereo- and enantioselectivities. Several intermediates for the synthesis of biologically important compounds were prepared using this novel catalytic asymmetric Mannich-type reaction, and at the same time, absolute and relative stereochemical assignments were made. In addition, it has been revealed that alkyl vinyl ethers reacted with N-acylimino esters in the presence of a catalytic amount of the Cu(II) catalyst to give the corresponding Mannich-type adducts in high yields with high enantioselectivities. This is the first example of catalytic asymmetric Mannich-type reactions with alkyl vinyl ethers. The reaction mechanism, structure of chiral catalyst-electrophile complexes, and transition states of these catalytic asymmetric reactions were assumed based on X-ray crystallographic analysis of the Cu(II)-chiral amine complex, PM3 calculations, and FT-IR analyses, etc. Finally, (1R,3R)-N-(3-hydroxy- 1-hydroxymethyl-3-phenylpropyl)dodecanamide (HPA-12, 1), a new inhibitor of ceramide trafficking from endoplasmic reticulum to the site of sphingomyerin (SM) synthesis, has been synthesized efficiently using the present Mannich-type reaction as a key step. The synthesis involved three steps (two-pot), and total yield was 82.9%.
- Kobayashi, Shu,Matsubara, Ryosuke,Nakamura, Yoshitaka,Kitagawa, Hidetoshi,Sugiura, Masaharu
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p. 2507 - 2515
(2007/10/03)
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- Non-carbonyl-stabilized metallocarbenoids in synthesis: The development of a tandem rhodium-catalyzed bamford-stevens/thermal aliphatic claisen rearrangement sequence
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A tandem rhodium-catalyzed Bamford-Stevens/Claisen rearrangement is presented. The tandem reaction uses Eschenmoser hydrazones for the in situ generation of non-carbonyl-stabilized diazo alkanes, which are presumably intercepted by Rh(II) catalysts to induce a 1,2-hydride migration. This sequence provides high levels of stereocontrol for the generation of simple acyclic (Z)-enol ethers. These enol ethers undergo either thermal or Lewis acid accelerated Claisen rearrangements to provide products of high diastereopurity. Also presented are cascade reactions, wherein a third chemical step occurs after the initial tandem sequence (i.e., Bamford-Stevens/Claisen/ene and Bamford-Stevens/Claisen/Cope). Copyright
- May, Jeremy A.,Stoltz, Brian M.
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p. 12426 - 12427
(2007/10/03)
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- Diphenyl-substituted heterocycles, processes for preparing them and their use as pharmaceutical compositions
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The invention relates to new diphenyl-substituted 5-ring heterocycles of general formula (I) wherein A, X and the groups R1, R2, R3, R4and R5are defined as in the claims, processes for preparing them
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- ORTHO SUBSTITUTED AROMATIC COMPOUNDS USEFUL AS ANTAGONISTS OF THE PAIN ENHANCING EFFECTS OF E-TYPE PROSTAGLANDINS
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The invention relates to compounds of the formula (I): STR1 wherein A, B and D are various ring systems such as phenyl, R. sup.1 includes carboxy, R 3 is hydrogen or C 1-4 alkyl and Z is a linking group such as--(CH(R 5)) m--wherein m is 2, 3 or 4, and R 5 includes hydrogen and methyl; and pharmaceutically acceptable salts and in vivo hydrolysable esters or amides thereof, processes for preparing these compounds, pharmaceutical compositions comprising them, and their use in the treatment of pain.
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- Behaviour of dioxolanones as chiral acyl anion equivalents
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The 1,3-dioxolan-4-ones readily derived from α-hydroxy acids act as convenient acyl anion equivalents by deprotonation - alkylation followed by flash vacuum pyrolysis. Conjugate addition of their anions to ethyl crotonate similarly gives β-methyl-γ-oxo esters and by using chiral dioxolanones these can be obtained in up to 86% e.e.
- Aitken, R. Alan,Thomas, Andrew W.
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p. 102 - 104
(2007/10/03)
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- Optically active hydroxybenzylamine
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The optically active benzylamine derivatives of the present invention are very useful for use as the asymmetric ligand of an asymmetric reducing agent. By using the optically active amine-boron complex prepared from the compound of the present invention, optically active products can be obtained in a specifically high optical yield. Moreover, the separation and recovery of the reaction products and asymmetric ligand can be easily achieved.
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