Regioselective Arylation Research Articles

ChemInform Abstract: Practical Total Synthesis of a Naturally Occurring Thielocin via the Regioselective Arylation of a Cyclic Boronate

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Aryllead-mediated synthesis of linear 3-arylpyranocoumarins: synthesis of robustin and robustic acid

The two naturally occurring linear 3-arylpyranocoumarins, robustin 1 and robustic acid 2, have been synthesised in nine steps from methyl 2,4,6-trihydroxyphenyl ketone, in 19% overall yield for robustin and 18% for robustic acid. Their syntheses involved, as a key step, the regioselective arylation of a functionalised 4-hydroxybenzo[l,2-b : 5,4-b′]dipyran-2-one with the appropriate aryllead triacetate.

ChemInform Abstract: Regioselective Aryl Radical Cyclization. Part 1. Stereocontrolled Synthesis of Linearly Condensed Hydroaromatic Carbocyclic Systems Through 6‐endo‐Ring Closures.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Practical total synthesis of a naturally occurring thielocin via the regioselective arylation of a cyclic boronate

Practical total synthesis of a naturally occurring thielocin via the regioselective arylation of a cyclic boronate

Practical total synthesis of a naturally occurring thielocin via the regioselective arylation of a cyclic boronate

The first total synthesis of thielocin B (2) has been achieved. Lewis acid-catalyzed arylation of the readily available cyclic boronate 8 provided the central portion of the molecule in a regiocontrolled manner. The desired natural compound 2 was then obtained in 7 steps and 31% yield from the intermediate 5.

ChemInform Abstract: Indoline Formation by Regioselective Aryl Radical Cyclization to Azomethine Bond.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Regioselective Aryl Radical Cyclization. 1. Stereocontrolled Synthesis of Linearly Condensed Hydroaromatic Carbocyclic Systems through 6-endo-Ring Closures

The stereocontrolled synthesis of trans-octahydroanthracenes (3), (11a- c), and (14a-c) and trans-octahydro-5aH-cyclohepta[b] naphthalene (27) through implementation of an efficient and highly regioselective 6-endo -trig-aryl radical cyclization of the respective 2-(o-bromoaryl)-1-me- thylenecyclohexanes (2), (10a-c), and (13a-c) and 2-(o-bromobenzyl)-1- methylenecycloheptane (41) with tri-n-butyltin hydride is described. The radical cyclization of 2-(o-bromobenzyl)-1-methylenecyclopentane (43), in contrast, produced a mixture of the cis- and trans-hexahydro- 1H-benz[f]indenes (38) and (37)

Indoline Formation by Regioselective Aryl Radical Cyclization to Azomethine Bond

Aryl radical-initiated cyclization of the ketimines derived from acetophenone and benzophenone occurred exclusively at the nitrogen end of the azomethine bond in an exo-5 mode to yield the corresponding indoline derivatives

Aryl- and alkynyltri-isopropoxytitanium reagents in regioselective carbon-carbon bond formation in azines

Regioselective arylation in the 4-position in pyridines results from 1:1-adduct formation between an aryltriisopropoxytitanium reagent and N-isobutyloxycarbonyl- or an N-silyloxymethyl-3-cyanopyridinium salt after successive DDQ dehydrogenation and cleavage of the 1-substituent. Complete regioselectivity for new CC bond formation in the 4-position results in the adduct formation between aryl- and phenylethynyltri-isopropoxytitanium reagents and pyrimidin-2(1 H)-ones; with ethynyltriisopropoxytitanium the new CC bond formation occurs at the 6-position.

Reactivity of 3,6-dimethoxy-3,6-dimethylcyclohexa-1,4-diene (part 2). Regioselective arylation of electron-rich aromatic compounds

The reaction of 3,6-dimethoxy-3,6-dimethylcyclohexa-1,4-diene (1) with electron-rich heterocycles (furan, thiophene, pyrrole, 2-methyl-furan indole) and 1,3,5-trimethoxybenzene in the presence of catalytic amounts of zinc dichloride or concentrated sulftiric acid leads to the corresponding 2-aryl substituted p-xylenes 4 in good yields and in a regioselective manner.

Regioselective arylation of unsaturated silanes under phase transfer catalysis conditions

The regioselective arylation of unsaturated compounds was carried out under metal complex and phase transfer conditions by the action of aryl iodides.

Regioselective arylation of ribose in adenosine and guanosine with the antitumor drug N2-methyl-9-hydroxyellipticinium acetate.

The transformation of the antitumor drug N2-methyl-9-hydroxy-ellipticinium by a peroxidase-hydrogen peroxide system, which has been shown to occur in vivo, leads to an electrophilic quinone-imine derivative. This unstable molecule arylates in vitro purine nucleosides and nucleotides, leading to regioselective adducts substituted only at the 2'-O position of the ribose, as shown by mass spectrometry and NMR. It is likely that an important preliminary step in this reaction is a stacking process between the ellipticinium ion and the purine rings, which might explain this regioselectivity.

Regioselective arylation of 3‐bromopyridine

AbstractThe addition of aryl Grignard reagents to the 1‐phenoxycarbonyl salt of 3‐bromopyridine affords 2‐aryl‐5‐bromo‐1‐phenoxycarbonyl‐1,2‐dihydropyridines and 4‐aryl‐3‐bromo‐1‐phenoxycarbonyl‐1,4‐dihydropyridines. The crude dihydropyridines were aromatized with o‐chloranil in refluxing toluene to give 4‐ and 6‐aryl‐3‐bromopyridines. The regioselectivity of this two‐step process, 6‐ vs. 4‐substitution, was examined and found to be dependent upon the structure of the Grignard reagent. Unhindered aryl Grignard reagents, e.g., phenyl and 2‐naphthyl, gave mainly 6‐aryl‐3‐bromopyridines (49‐52%) along with 9% of the 4‐substituted isomer and less than 4% of the 2‐aryl‐3‐bromopyridine. Hindered aryl Grignard reagents, e.g., o‐tolyl and 1‐naphthyl, are less regioselective. When a catalytic amount of cuprous iodide is present during the Grignard reaction, nearly exclusive 1,4‐addition results. The crude 4‐aryl‐3‐bromo‐1,4‐dihydropyridines were aromatized with p‐chloranil to provide 4‐aryl‐3‐bromopyridines in good yield and high isomeric purity. The sequential use of the cuprous iodide‐catalyzed Grignard reaction and the “normal” Grignard reaction provided a regiospeci‐fic synthesis of 3‐bromo‐6‐(p‐methoxyphenyl)‐4‐phenylpyridine from 3‐bromopyridine.

Regioselective arylation of silyl enol ethers of methyl ketones with aryl bromides

Regioselective arylation of silyl enol ethers of methyl ketones with aryl bromides

Tetraphenylbismuth monotrifluoroacetate: a new reagent for regioselective aryl ether formation

Tetraphenylbismuth trifluoroacetate is a useful new reagent for selective formation of the aryl–oxygen bond, and in its reactivity complements the behaviour of other Biv arylating agents.