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Hetero arenes

Thiazoles are important heterocycles and continue to be interesting synthetic targets because several classes of annulated thiazoles and thiazolyl (hetero)arenes display a diverse array of biological activities. [Pg.65]

M= (transition) metal ar= (hetero) arene bridging unit L - ar= complexii ligand - (hetero) arene Fig. 2 Schematic drawings of metal-containing PAE structures (see text)... [Pg.58]

The DBU/bis(trimethylsilyl)acetamide (BTMSA) double condensation of nitro(hetero)arenes with cinnamyl-based sulfones yields 2-aryl-4-arylsulfonyl heterocycles in good to excellent yields (DBU= l,8-diazabicyclo[5.4.0]-undec-7-ene Scheme 33) <1997TL4913, 1998T2607>. [Pg.729]

Scheme 6.15 Reaction of styrene and 4-chlorostyrene with various (hetero)arenes GC conversion of styrene/GC product yield (regioselectivity). Reaction conditions 0.5 mmol styrene/ 4-chlorostyrene, 10mol% FeCl3, 5mLarene, 80°C, 4h (a)... Scheme 6.15 Reaction of styrene and 4-chlorostyrene with various (hetero)arenes GC conversion of styrene/GC product yield (regioselectivity). Reaction conditions 0.5 mmol styrene/ 4-chlorostyrene, 10mol% FeCl3, 5mLarene, 80°C, 4h (a)...
The R- radicals can also undergo cross coupling with alkenes and with hetero-arenes.2... [Pg.5]

Scheme 4 A coupling-aminovinylation sequence to P-amino vinyl hetero arenes 6... Scheme 4 A coupling-aminovinylation sequence to P-amino vinyl hetero arenes 6...
Pyrimidines by a Two-Step Sequence of Consecutive SCR of (Hetero)Arenes, Oxalyl Chloride, Alkynes, and Cyclocondensation with Guanidinium Salts... [Pg.48]

An interesting difference between the homoaryl and heteroaryl compounds is found in the reaction of 2-(tributylstannyl)-furan and -thiophene towards benzyhydryl cations.115 Whereas homoarylstannanes appear always to undergo ipso attack by electrophiles, the relative reactivities at the 2 (ipso) and 5 position in these two hetero-arenes are shown in Scheme 7-2 at both positions the reactivity is increased, but the effect is much larger at the 5-position. If C-Sn hyperconjugation is important in stabilising the Wheland intermediate, this unusual regioselectivity might be taken to imply that here there is an early transition state in which such an effect would be less important. [Pg.109]

Whether the reaction is inter- or intramolecular, the Heck reaction generates vinyl(hetero)arenes or dienes from an alkene and a (hetero)aryl or alkenyl halide [130]. This reaction has great versatility and is applicable to a wide range of aryl and alkene species. Mechanistically, the Heck reaction varies from that depicted in Fig. 4.3. While the oxidative addition of the halogen species occurs, the transmetalation step is replaced by the coordination of the alkene. This is followed by a migratory insertion which essentially substitutes for the cross-coupling step. The product is released not by a reductive elimination, but by a 3-hydride elimination sequence (Fig. 4.5). [Pg.231]

Shi described a palladium(II) catalyzed cross-coupling of electron rich (hetero) arenes with aryl boronic acids (Scheme 22) [45]. A major strategic challenge was avoiding homo-coupling of the aryl boronic acids in the presence of palladium(II). [Pg.100]

Indoles and pyrroles have also been shown to undergo C-H alkenylation reactions. In these cases the process involves the coupling of the unfunctionalized (hetero) arene with an olefin (Scheme 36). [Pg.106]

The scope of this reaction is limited to electron-rich arenes and heteroarenes such as thiophenes, pyrroles, furans, indoles, and alkoxybenzenes as nucleophilic partners, corresponding to a Mayr ir-nucleophilicily parameter N>-1 [75-78], Electron-neutral to electron-deficient iodo(hetero)arenes are suitable electrophilic partners. Aryl halides or pseudohalides that are less reactive towards oxidative addition (Br, Cl, OTf) are not sufficiently reactive partners in this reaction. The reactivity of sterically hindered and/or ortho substituted iodoarenes has not been demonstrated. However biaryls bearing one ortho substituent of relatively small steric demand (e.g., from methoxybenzene or /V-mcthylindole) have been prepared. [Pg.240]

Yanagisawa S, Sudo T, Noyori R, Itami K (2006) Direct C-H arylation of (Hetero)arenes with aryl iodides via rhodium catalysis. J Am Chem Soc 128 11748-11749... [Pg.275]

However, given that transition metal catalysis had arguably the strongest impact through the development of efficient methods for bi(hetero)aryl formations, we focus here largely on C—H bond functionalizations for catalytic direct arylations of (hetero) arenes [24]. [Pg.261]

Catalytic direct arylations can be accomplished in an oxidative fashion, provided that stoichiometric oxidants are present. These transformations can be achieved either with stoichiometric amounts of organometallic reagents as arylating reagents (Scheme 9.6a) or directly with (hetero)arenes (Scheme9.6b). Unfortunately, oxidative... [Pg.262]

Table 9.1 Selected arylation reactions of (hetero)arenes with halogenated electron-deficient heteroarenes (where necessary arrows indicate the position of C—H bond functionalization). Table 9.1 Selected arylation reactions of (hetero)arenes with halogenated electron-deficient heteroarenes (where necessary arrows indicate the position of C—H bond functionalization).
Intermolecular dehydrogenative oxidative homocouplings of (hetero)arenes turned out to be among the most important methods for the synthesis of symmetrically substituted biaryls [122]. A recent illustrative example is oxidative coupling reactions of 2-naphthols, which were accomplished in an asymmetric fashion employing an inexpensive iron catalyst (Scheme 9.47) [123]. [Pg.295]

While intramolecular oxidative arylations and also intermolecular homocouplings can be performed in a highly selective fashion, a significant challenge is to achieve chemoselectivities in intermolecular oxidative arylations between two different (hetero)arenes. [Pg.296]

Shi and co-workers have developed various types of C—H bond functionalization and C—C bond formation. Recently, they reported a novel transformation to realize ortho-arylation of acetanilides with trialkoxyarylsilanes through direct C—H functionalization (Equation 11.34) [72]. Furthermore, they also demonstrated a novel method for the direct construction of biaryl C—C bonds via Pd(II)-catalyzed cross-coupling of (hetero)arenes and various arylboronic acids [73]. Various aromatic rings show good selectivity, even without directing groups, under mild conditions. [Pg.351]

Modified conditions have been developed for the preparation of cyanoheteroarenes from hetero-arene Woxides by the Reissert-Henze reaction, using TMSCN and DBU (Equation (9)). DBU as base is much more productive than triethylamine, which gave only 37% yield in 180 minutes compared to 76% in 40 minutes for the example shown <92H(33)2l l >. The use of tri- -butyltin cyanide with benzoyl chloride for the preparation of Reissert compounds when applied to phthalazine gave... [Pg.23]

The unique bonding characteristics of aromatics, the stability of the benzene ring system, and the varied and often complex chemistry of arenes and hetero-arenes have fascinated chemists for close to two centuries. Benzene rings are omnipresent in organic chemistry and they find important applications in the pharma, agrochemical, and polymer fields. New applications of aromatics include sectors such as functional materials and molecular machines. [Pg.1]

High-potential quinones, such as DDQ and chloranil, are important stoichiometric reagents in organic synthesis with notable applications in the oxidative functionalization of activated C-H bonds and dehydrogenation to form (hetero)arenes [1]. These reactions can be rendered catalytic in quinone by using certain transition metal salts, anodic oxidation, or molecular oxygen to regenerate the quinone in situ. [Pg.229]

Although palladium-catalyzed cross-coupling reactions provide an efficient entry to C-arylated indoles, these reactions require the preparation of functionalized hetero-arenes such as boronates and halides. Therefore, C-arylation reactions of azole and related heteroarenes via direct C-H bond functionalization of the parent heteroar-enes would be much more favorable. In 2004, Sames reported a selective palladium-catalyzed C2-arylation of W-substituted indoles via direct C—H bond arylation [199]. Use CsOAc as the base and low concentration of the substrates proved to be critical for the success of this methodology. [Pg.224]

Direct C—H arylation of (hetero)arenes under microwave irradiation 13CEJ1158. [Pg.212]

Direct metal-catalyzed trifluoromethylation of (hetero)arenes 13ASC617. [Pg.220]


See other pages where Hetero arenes is mentioned: [Pg.151]    [Pg.749]    [Pg.528]    [Pg.136]    [Pg.181]    [Pg.209]    [Pg.22]    [Pg.107]    [Pg.212]    [Pg.263]    [Pg.264]    [Pg.265]    [Pg.281]    [Pg.293]    [Pg.293]    [Pg.295]    [Pg.297]    [Pg.298]    [Pg.325]    [Pg.229]   


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Hetero arenes alkylation

Hetero arenes reduction

Hetero-Substituted Arenes

Oxidative Arylations of (Hetero)arenes

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