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Aryl compounds intramolecular

Palladium chemistry involving heterocycles has its unique characteristics stemming from the heterocycles inherently different structural and electronic properties in comparison to the corresponding carbocyclic aryl compounds. One example illustrating the striking difference in reactivity between a heteroarene and a carbocyclic arene is the heteroaryl Heck reaction (vide infra, see Section 1.4). We define a heteroaryl Heck reaction as an intermolecular or an intramolecular Heck reaction occurring onto a heteroaryl recipient. Intermolecular Heck reactions of carbocyclic arenes as the recipients are rare [12a-d], whereas heterocycles including thiophenes, furans, thiazoles, oxazoles, imidazoles, pyrroles and indoles, etc. are excellent substrates. For instance, the heteroaryl Heck reaction of 2-chloro-3,6-diethylpyrazine (1) and benzoxazole occurred at the C(2) position of benzoxazole to elaborate pyrazinylbenzoxazole 2 [12e]. [Pg.1]

Note The pictorial term scrambling is used in mass spectrometry to describe rapid processes of (intramolecular) positional interchange of atoms. Scrambling may occur with hydrogens or may involve the complete carbon skeleton of an ion. Aryl radical ions and protonated aryl compounds are well known for their numerous scrambling processes. [54,55]... [Pg.252]

Benzyne also reacts with compounds containing nucleophilic carbon atoms such as enolates and aryl anions. Intramolecular nucleophilic addition to an aryne by the ortho ring carbon atom of another benzene ring substituted... [Pg.188]

In the Grignard reagent of a 2,6-substituted aryl compound, as shown in eq. (4.19), most of the THF is removed from the reaction solution by distilling, and n-hexane is added and cooled to yield the R2Mg type compound (the right-hand compound of the reaction as shown in eq. (4.19)) in the Schlenk equilibrium as crystals. The structure of R2Mg is found such that magnesium is intramolecularly... [Pg.57]

In the reaction of Q,/3-unsaturated ketones and esters, sometimes simple Michael-type addition (insertion and hydrogenolysis, or hydroarylation, and hydroalkenylation) of alkenes is observed[53,54]. For example, a simple addition product 56 to methyl vinyl ketone was obtained by the reaction of the heteroaromatic iodide 55[S5]. The corresponding bromide affords the usual insertion-elimination product. Saturated ketones are obtained cleanly by hydroarylation of o,/3l-unsaturated ketones with aryl halides in the presence of sodium formate, which hydrogenolyses the R—Pd—I intermediate to R— Pd—H[56]. Intramolecular hydroarylation is a useful reaction. The diiodide 57 reacts smoothly with sodium formate to give a model compound for the afla-toxin 58. (see Section 1.1.6)[57]. Use of triethylammonium formate and BU4NCI gives better results. [Pg.136]

Transannular Te N interactions have also been employed to stabilize compounds of the type 15.24 with terminal Te=E (E = S, Se) bonds.The Te=Se bond length in 15.24b is 2.44 A (cf. 2.54 A for a Te-S single bond) and d(Te N) = 2.62 A. Intramolecular coordination was also employed in the isolation of the first aryl-selenenium and -tellurenium cations 15.25a,b as [PEg] salts. [Pg.305]

A number of other examples of intramolecular arylations in heterocyclic compounds have been described and reviewed. ... [Pg.151]

An intramolecular palladium(o)-catalyzed cross-coupling of an aryl iodide with a trans vinylstannane is the penultimate maneuver in the Stille-Hegedus total synthesis of (S)-zearalenone (142) (see Scheme 38).59 In the event, exposure of compound 140 to Pd(PPh3)4 catalyst on a 20% cross-linked polystyrene support in refluxing toluene brings about the desired macrocyclization, affording the 14-membered macrolide 141 in 54% yield. Acid-induced hydrolysis of the two methoxyethoxymethyl (MEM) ethers completes the total synthesis of 142. [Pg.598]

The disadvantages of the Gomberg-Bachmann arylations are significantly reduced in their intramolecular analogues, particularly in Pschorr s synthesis of phenan-threne and related compounds. [Pg.261]

In certain cases, Michael reactions can take place under acidic conditions. Michael-type addition of radicals to conjugated carbonyl compounds is also known.Radical addition can be catalyzed by Yb(OTf)3, but radicals add under standard conditions as well, even intramolecularly. Electrochemical-initiated Michael additions are known, and aryl halides add in the presence of NiBr2. Michael reactions are sometimes applied to substrates of the type C=C—Z, where the co-products are conjugated systems of the type C=C—Indeed, because of the greater susceptibility of triple bonds to nucleophilic attack, it is even possible for nonactivated alkynes (e.g., acetylene), to be substrates in this... [Pg.1024]

Intramolecular arylations are possible and several studies have examined the synthesis of biologically active compounds such as oxindoles.181 For example, a synthesis of physovenine has been reported using this methodology. [Pg.730]


See other pages where Aryl compounds intramolecular is mentioned: [Pg.181]    [Pg.221]    [Pg.929]    [Pg.1107]    [Pg.280]    [Pg.266]    [Pg.266]    [Pg.23]    [Pg.140]    [Pg.251]    [Pg.340]    [Pg.224]    [Pg.282]    [Pg.24]    [Pg.137]    [Pg.876]    [Pg.72]    [Pg.1464]    [Pg.1671]    [Pg.143]    [Pg.242]    [Pg.306]    [Pg.69]    [Pg.137]    [Pg.876]    [Pg.73]    [Pg.185]    [Pg.20]   
See also in sourсe #XX -- [ Pg.3 , Pg.505 ]

See also in sourсe #XX -- [ Pg.3 , Pg.505 ]




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Aryl compounds intramolecular coupling reactions

Arylation compounds

Arylation intramolecular

Carbonyl compounds intramolecular arylation

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