A 1,5-Bifunctional Organomagnesium Reagent for the Synthesis of Disubstituted Anthracenes and Anthrones

The preparation of a 1,5-bifunctional organomagnesium alkoxide reagent by a deprotonation–magnesiation sequence is described. This reagent reacts with carboxylic acid esters to incorporate the carboxyl carbon atom of the ester into the newly formed ring. The magnesium bisalkoxide resulting from this double nucleophilic attack is subsequently transformed in situ into halogenated disubstituted anthracenes, monosubstituted anthracenes, anthrones, or 9-substituted dihydroanthracene-cis-diols by variation of the acidic workup procedures.

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Purification of a GlutathioneS-Transferase and a Glutathione Conjugate-Specific Dehydrogenase Involved in Isoprene Metabolism in Rhodococcussp. Strain AD45

Journal of Bacteriology ◽

10.1128/jb.181.7.2094-2101.1999 ◽

1999 ◽

Vol 181 (7) ◽

pp. 2094-2101 ◽

Cited By ~ 55

Author(s):

Johan E. T. van Hylckama Vlieg ◽

Jaap Kingma ◽

Wim Kruizinga ◽

Dick B. Janssen

Keyword(s):

Nuclear Magnetic Resonance ◽

Carboxylic Acid ◽

Magnetic Resonance ◽

Carbon Atom ◽

Ring Opening ◽

Nucleophilic Attack ◽

Epoxide Ring ◽

Resonance Spectroscopy ◽

Secondary Alcohols ◽

Tertiary Carbon

ABSTRACT A glutathione S-transferase (GST) with activity toward 1,2-epoxy-2-methyl-3-butene (isoprene monoxide) andcis-1,2-dichloroepoxyethane was purified from the isoprene-utilizing bacterium Rhodococcus sp. strain AD45. The homodimeric enzyme (two subunits of 27 kDa each) catalyzed the glutathione (GSH)-dependent ring opening of various epoxides. At 5 mM GSH, the enzyme followed Michaelis-Menten kinetics for isoprene monoxide and cis-1,2-dichloroepoxyethane, withV max values of 66 and 2.4 μmol min−1 mg of protein−1 andKm values of 0.3 and 0.1 mM for isoprene monoxide and cis-1,2-dichloroepoxyethane, respectively. Activities increased linearly with the GSH concentration up to 25 mM.1H nuclear magnetic resonance spectroscopy showed that the product of GSH conjugation to isoprene monoxide was 1-hydroxy-2-glutathionyl-2-methyl-3-butene (HGMB). Thus, nucleophilic attack of GSH occurred on the tertiary carbon atom of the epoxide ring. HGMB was further converted by an NAD+-dependent dehydrogenase, and this enzyme was also purified from isoprene-grown cells. The homodimeric enzyme (two subunits of 25 kDa each) showed a high activity for HGMB, whereas simple primary and secondary alcohols were not oxidized. The enzyme catalyzed the sequential oxidation of the alcohol function to the corresponding aldehyde and carboxylic acid and followed Michaelis-Menten kinetics with respect to NAD+ and HGMB. The results suggest that the initial steps in isoprene metabolism are a monooxygenase-catalyzed conversion to isoprene monoxide, a GST-catalyzed conjugation to HGMB, and a dehydrogenase-catalyzed two-step oxidation to 2-glutathionyl-2-methyl-3-butenoic acid.

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Gold-catalyzed alkylation of silyl enol ethers with ortho-alkynylbenzoic acid esters

Beilstein Journal of Organic Chemistry ◽

10.3762/bjoc.7.76 ◽

2011 ◽

Vol 7 ◽

pp. 648-652 ◽

Cited By ~ 5

Author(s):

Haruo Aikawa ◽

Tetsuro Kaneko ◽

Naoki Asao ◽

Yoshinori Yamamoto

Keyword(s):

Alkylating Agents ◽

Gold Catalyst ◽

Nucleophilic Attack ◽

Enol Ether ◽

Enol Ethers ◽

Silyl Enol Ethers ◽

Silyl Enol Ether ◽

Leaving Groups ◽

Acid Esters

Unprecedented alkylation of silyl enol ethers has been developed by the use of ortho-alkynylbenzoic acid alkyl esters as alkylating agents in the presence of a gold catalyst. The reaction probably proceeds through the gold-induced in situ construction of leaving groups and subsequent nucleophilic attack on the silyl enol ethers. The generated leaving compound abstracts a proton to regenerate the silyl enol ether structure.

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Ketones from Nickel-Catalyzed Decarboxylative, Non-Symmetric Cross-Electrophile Coupling of Carboxylic Acid Esters

10.26434/chemrxiv.8019419.v1 ◽

2019 ◽

Author(s):

Jiang Wang ◽

Brian P. Cary ◽

Peyton Beyer ◽

Samuel H. Gellman ◽

Daniel Weix

Keyword(s):

Carboxylic Acid ◽

Solid Support ◽

Reaction Conditions ◽

Decarboxylative Coupling ◽

New Strategy ◽

The Cross ◽

Acyl Donors ◽

Acid Esters

A new strategy for the synthesis of ketones is presented based upon the decarboxylative coupling of N-hydroxyphthalimide (NHP) esters with S-2-pyridyl thioesters. The reactions are selective for the cross-coupled product because NHP esters act as radical donors and the thioesters act as acyl donors. The reaction conditions are general and mild, with over 40 examples presented, including larger fragments and the 20-mer peptide Exendin(9-39) on solid support.

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The mechanism of alkylation of benzene with carboxylic acid esters induced by titanium tetrachloride

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc19762878 ◽

1976 ◽

Vol 41 (10) ◽

pp. 2878-2884 ◽

Cited By ~ 1

Author(s):

K. Mach ◽

E. Drahorádová

Keyword(s):

Carboxylic Acid ◽

Titanium Tetrachloride ◽

Alkylation Of Benzene ◽

Acid Esters

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Understanding the reaction mechanism of the regioselective piperidinolysis of aryl 1-(2,4-dinitronaphthyl) ethers in DMSO: Kinetic and DFT studies

Progress in Reaction Kinetics and Mechanism ◽

10.1177/14686783211027446 ◽

2021 ◽

Vol 46 ◽

pp. 146867832110274

Author(s):

Yasmen M Moghazy ◽

Nagwa MM Hamada ◽

Magda F Fathalla ◽

Yasser R Elmarassi ◽

Ezzat A Hamed ◽

...

Keyword(s):

Carbon Atom ◽

Density Functional ◽

Function Analysis ◽

Density Functional Theory Method ◽

Activation Parameters ◽

Kinetic Studies ◽

Nucleophilic Attack ◽

Common Mechanism ◽

Slow Step ◽

Rate Determining Step

Reactions of aryl 1-(2,4-dinitronaphthyl) ethers with piperidine in dimethyl sulfoxide at 25oC resulted in substitution of the aryloxy group at the ipso carbon atom. The reaction was measured spectrophotochemically and the kinetic studies suggested that the titled reaction is accurately third order. The mechanism is began by fast nucleophilic attack of piperidine on C1 to form zwitterion intermediate (I) followed by deprotonation of zwitterion intermediate (I) to the Meisenheimer ion (II) in a slow step, that is, SB catalysis. The regular variation of activation parameters suggested that the reaction proceeded through a common mechanism. The Hammett equation using reaction constant σo values and Brønsted coefficient value showed that the reaction is poorly dependent on aryloxy substituent and the reaction was significantly associative and Meisenheimer intermediate-like. The mechanism of piperidinolysis has been theoretically investigated using density functional theory method using B3LYP/6-311G(d,p) computational level. The combination between experimental and computational studies predicts what mechanism is followed either through uncatalyzed or catalyzed reaction pathways, that is, SB and SB-GA. The global parameters of the reactants, the proposed activated complexes, and the local Fukui function analysis explained that C1 carbon atom is the most electrophilic center of ether. Also, kinetics and theoretical calculation of activation energies indicated that the mechanism of the piperidinolysis passed through a two-step mechanism and the proton transfer process was the rate determining step.

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Computational and experimental investigations of one-step conversion of poly(carbonate)s into value-added poly(aryl ether sulfone)s

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1600924113 ◽

2016 ◽

Vol 113 (28) ◽

pp. 7722-7726 ◽

Cited By ~ 29

Author(s):

Gavin O. Jones ◽

Alexander Yuen ◽

Rudy J. Wojtecki ◽

James L. Hedrick ◽

Jeannette M. García

Keyword(s):

High Performance ◽

Density Functional ◽

Value Added ◽

Single Step ◽

Nucleophilic Attack ◽

Experimental Investigations ◽

Aryl Ether ◽

One Step ◽

Poly Carbonate

It is estimated that ∼2.7 million tons poly(carbonate)s (PCs) are produced annually worldwide. In 2008, retailers pulled products from store shelves after reports of bisphenol A (BPA) leaching from baby bottles, reusable drink bottles, and other retail products. Since PCs are not typically recycled, a need for the repurposing of the PC waste has arisen. We report the one-step synthesis of poly(aryl ether sulfone)s (PSUs) from the depolymerization of PCs and in situ polycondensation with bis(aryl fluorides) in the presence of carbonate salts. PSUs are high-performance engineering thermoplastics that are commonly used for reverse osmosis and water purification membranes, medical equipment, as well as high temperature applications. PSUs generated through this cascade approach were isolated in high purity and yield with the expected thermal properties and represent a procedure for direct conversion of one class of polymer to another in a single step. Computational investigations performed with density functional theory predict that the carbonate salt plays two important catalytic roles in this reaction: it decomposes the PCs by nucleophilic attack, and in the subsequent polyether formation process, it promotes the reaction of phenolate dimers formed in situ with the aryl fluorides present. We envision repurposing poly(BPA carbonate) for the production of value-added polymers.

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