577-56-0Relevant articles and documents
Ground and excited state hydrogen atom transfer reactions and cyclization of 2-acetylbenzoic acid
Santos,Vargas,Moreno,Manzano,Lluch,Douhal
, p. 9331 - 9341 (2004)
We present experimental and theoretical studies of the ring-chain tautomerism (H-atom transfer and cyclization) for 2-acetylbenzoic acid at both ground and electronically first excited states. 1H and 13C NMR studies in solution confirm the existence of equilibrium between the open and ring structures at the ground state, with the ring one being dominant (～90%). Temperature-dependent 1H NMR experiments allowed obtaining the thermodynamic and kinetic parameters at the coalescence temperature (380 K). Fluorescence measurements disclose the involvement of highly efficient nonradiative processes in agreement with the theoretical data. Electronic calculations for the ground state give additional information on the different conformers of the open tautomer. In agreement with the experiment the most stable structure is of the closed ring tautomer, and it is obtained after additional internal rotations of the -COOH and -CO(CH3) fragments. Intrinsic reaction coordinate calculations indicate that the ring formation/breaking and the H-atom transfer are taking place in a concerted but not synchronous manner. At S1 the most stable form is the open one, for which different conformers are also found. The influence of the solvent is also accounted for through a model that considers the solvent as a continuum at both the ground and excited electronic states. No major differences were observed when comparing both gas and condensed phase results, so calculations of the isolated molecule should give a picture of the reaction which is experimentally observed in solution.
Regio- and Stereoselective Synthesis of (Z)-3-Ylidenephthalides via H3PMo12O40-Catalyzed Cyclization of 2-Acylbenzoic Acids with Benzylic Alcohols
Yang, Guoping,Li, Ke,Lin, Xiaoling,Li, Yijin,Cui, Chengxing,Li, Shixiong,Cheng, Yuanyuan,Liu, Yufeng
supporting information, p. 3017 - 3022 (2021/09/13)
We report an exclusively tandem C—O and C—C bond forming beyond the esterification and cyclization reaction of 2-acylbenzoic acids with alcohols to regio- and stereoselective synthesis of the (Z)-3-ylidenephthalides. The reaction uses the nontoxic, inexpensive H3PMo12O40 as catalyst and produces water as the sole by-product, making the reaction environmentally benign and sustainable. Moreover, this reaction features an eco-friendly reaction condition, facile scalability, and easy derivatization of the products to drugs and bioactive compounds. The mechanism studies and density functional theory calculations reveal that the appropriate acid catalyst is the key to the selectivity of this transformation.
Synthesis of dibenzocycloketones by acyl radical cyclization from aromatic carboxylic acids using methylene blue as a photocatalyst
Jiang, Hongshuo,Mao, Guijie,Wu, Hongfeng,An, Qi,Zuo, Minghui,Guo, Weihao,Xu, Chunzhao,Sun, Zhizhong,Chu, Wenyi
supporting information, p. 5368 - 5373 (2019/10/11)
An efficient intramolecular radical cyclization reaction via photoredox catalysis was developed for the synthesis of dibenzocycloketone derivatives using methylene blue as a photosensitizer. This strategy could be widely used to synthesize large heterocycles due to the unique reactivity of phosphoranyl radicals formed by a polar/SET crossover between an aromatic carboxylic acid and a phosphine radical cation. Attractive features of this process include generation of an acyl radical by an inexpensive and metal-free photocatalyst, which effectively undergoes a cyclization process.
A biocatalytic method for the chemoselective aerobic oxidation of aldehydes to carboxylic acids
Knaus, Tanja,Tseliou, Vasilis,Humphreys, Luke D.,Scrutton, Nigel S.,Mutti, Francesco G.
supporting information, p. 3931 - 3943 (2018/09/11)
Herein, we present a study on the oxidation of aldehydes to carboxylic acids using three recombinant aldehyde dehydrogenases (ALDHs). The ALDHs were used in purified form with a nicotinamide oxidase (NOx), which recycles the catalytic NAD+ at the expense of dioxygen (air at atmospheric pressure). The reaction was studied also with lyophilised whole cell as well as resting cell biocatalysts for more convenient practical application. The optimised biocatalytic oxidation runs in phosphate buffer at pH 8.5 and at 40 °C. From a set of sixty-one aliphatic, aryl-Aliphatic, benzylic, hetero-Aromatic and bicyclic aldehydes, fifty were converted with elevated yield (up to >99%). The exceptions were a few ortho-substituted benzaldehydes, bicyclic heteroaromatic aldehydes and 2-phenylpropanal. In all cases, the expected carboxylic acid was shown to be the only product (>99% chemoselectivity). Other oxidisable functionalities within the same molecule (e.g. hydroxyl, alkene, and heteroaromatic nitrogen or sulphur atoms) remained untouched. The reaction was scaled for the oxidation of 5-(hydroxymethyl)furfural (2 g), a bio-based starting material, to afford 5-(hydroxymethyl)furoic acid in 61% isolated yield. The new biocatalytic method avoids the use of toxic or unsafe oxidants, strong acids or bases, or undesired solvents. It shows applicability across a wide range of substrates, and retains perfect chemoselectivity. Alternative oxidisable groups were not converted, and other classical side-reactions (e.g. halogenation of unsaturated functionalities, Dakin-Type oxidation) did not occur. In comparison to other established enzymatic methods such as the use of oxidases (where the concomitant oxidation of alcohols and aldehydes is common), ALDHs offer greatly improved selectivity.
Aerobic Photooxidative Synthesis of β-Alkoxy Monohydroperoxides Using an Organo Photoredox Catalyst Controlled by a Base
Asano, Yuya,Nagasawa, Yoshitomo,Yamaguchi, Eiji,Itoh, Akichika
supporting information, p. 409 - 412 (2018/02/21)
Transition-metal-free synthesis of β-alkoxy monohydroperoxides via aerobic photooxidation using an acridinium photocatalyst was developed. This method enables the synthesis of some novel hydroperoxides. The peroxide source is molecular oxygen, which is cost-effective and atomically efficient. Magnesium oxide plays an important role as a base in the catalytic system.
Room Temperature Carbonylation of (Hetero) Aryl Pentafluorobenzenesulfonates and Triflates using Palladium-Cobalt Bimetallic Catalyst: Dual Role of Cobalt Carbonyl
Joseph, Jayan T.,Sajith, Ayyiliath M.,Ningegowda, Revanna C.,Shashikanth, Sheena
, p. 419 - 425 (2017/02/10)
An efficient method for the carbonylation of (hetero) aryl pentafluorobenzenesulfonates and triflates under exceptionally mild conditions using palladium/dicobalt octacarbonyl [Pd/Co2(CO)8] has been developed. Besides acting as carbon monoxide (CO) source, Co2(CO)8enhances the reaction rate by accelerating the CO insertion through an in situ generated bimetallic palladium cobalt tetracarbonyl [Pd-Co(CO)4] complex. Under the optimized reaction condition, carbonylation of a wide range of activated and deactivated, as well as sterically hindered and heteroaromatic, substrates proceeded efficiently at room temperature. The high chemoselectivity and improved synthesis of biologically relevant Isoguvacine and Lazabemide intermediates highlights its scope as a valuable synthetic method. The generality of this protocol was further extended to other electrophiles (bromides, chlorides and tosylates). (Figure presented.).
Method for preparing isobenzofuran-1(3H)-one compounds
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Paragraph 0067; 0068; 0069; 0070; 0071; 0072; 0073, (2016/10/10)
The invention provides a method for preparing isobenzofuran-1(3H)-one compounds. R1, R2 and p are defined in the specification.
Synthesis of (R)-3-methylphthalide by reductive cyclization of a 2-acylarylcarboxylate using the chiral boronic ester TarB-H and sodium borohydride
De Souza, Aline Aparecida Nunes,Taylor, Jason Guy
, p. 657 - 660 (2017/01/16)
Background: Phthalides are pervasive benzolactone structural frameworks in nature and have a broad profile of biological activities. Catalytic asymmetric reduction with the in situ lactonization of 2-acylarylcarboxylate compounds is an efficient strategy for chiral phthalide synthesis. The tartaric acid-derived reagent TarB-X is capable of mediating the asymmetric reduction of aromatic ketones using either LiBH4 or NaBH4 as the reductant. Up until now, the asymmetric reduction by Tarb- H/NaBH4 had not been applied to the synthesis of chiral phthalides. Methods: The requsite substrate, methyl 2-acetylbenzoate was obtained by a two step reaction starting from phthalic anhydride and maloninc acid. Tarb-H was obtained by treatment of L-(+)-tartaric acid with phenylboronic acid. The catalyst and NaBH4 were reacted with methyl 2-acetylbenzoate at room temperature for 1 h. The structure of (R)-3-Methylphthalide was established by NMR and mass spectrometry and its enantiomeric excess was determined by HPLC. The relative configuration was deduced by comparison of the optical rotation with data given in the literature. Results: (R)-3-Methylphthalide was obtained in moderte yield and high enantiomeric excess. Conclusion: (R)-3-methylphthalide was prepared in high enantiomeric excesses using an inexpensive and easily synthesized tartaric acid derived boronic ester (TarB-H) with sodium borohydride. The chiral phthalide was obtained in an open flask by reductive cyclization of a 2-acylarylcarboxylate.
MIL-101 as reusable solid catalyst for autoxidation of benzylic hydrocarbons in the absence of additional oxidizing reagents
Santiago-Portillo, Andrea,Navalón, Sergio,Cirujano, Francisco G.,Xamena, Francesc X. Llabrés I,Alvaro, Mercedes,Garcia, Hermenegildo
, p. 3216 - 3224 (2015/06/16)
Materiaux de l'Institute Lavosier-101 (MIL-101) promotes benzylic oxidation of hydrocarbons exclusively by molecular oxygen in the absence of any other oxidizing reagent or initiator. Using indane as model compound, the selectivity toward the wanted ol/one mixture is higher for MIL-101(Cr) (87% selectivity at 30% conversion) than for MIL-101(Fe) (71% selectivity at 30% conversion), a fact that was associated with the preferential adsorption of indane within the pore system. Product distribution and quenching experiments with 2,2,6,6-tetramethyl-1-piperidinyloxy, benzoic acid, and dimethylformamide show that the reaction mechanism is a radical chain autoxidation of the benzylic positions by molecular oxygen, and the differences in selectivity have been attributed to the occurrence of the autoxidation process inside or outside the metal organic framework pores. MIL-101 is reusable, does not leach metals to the solution, and maintains the crystal structure during the reaction. The scope of the benzylic oxidation was expanded to other benzylic compounds including ethylbenzene, n-butylbenzene, iso-butylbenzene, 1-bromo-4-butylbenzene, sec-butylbenzene, and cumene.
Electrophilicity and nucleophilicity of commonly used aldehydes
Pratihar, Sanjay
, p. 5781 - 5788 (2014/07/22)
The present approach for determining the electrophilicity (E) and nucleophilicity (N) of aldehydes includes a kinetic study of KMNO4 oxidation and NaBH4 reduction of aldehydes. A transition state analysis of the KMNO4 promoted aldehyde oxidation reaction has been performed, which shows a very good correlation with experimental results. The validity of the experimental method has been tested using the experimental activation parameters of the two reactions. The utility of the present approach is further demonstrated by the theoretical versus experimental relationship, which provides easy access to E and N values for various aldehydes and offers an at-a-glance assessment of the chemical reactivity of aldehydes in various reactions. the Partner Organisations 2014.
