Reactions of Aromatics and Heteroaromatics

Aryl-aryl coupling is an important synthetic reaction. Efficient aryl-aryl coupling is possible by Pd-catalyzed cross couplings of aryl halides with aryl metal (Mg, Zn, B, Sn, Si) compounds, and the methods have wide applications. On the other hand, a simple Pd-catalyzed arylation of arenes with aryl halides has been known. Although less attention has been paid, the importance of the reaction is increasing as more efficient methods of aryl-aryl bond formation become available. The arylation of arenes with aryl haUdes is treated in this section. 

In contrast to facile reactions of aryl halides with alkenes and alkynes, reactions of aromatic compounds with aryl halides have received less attention. Only intramolecular arylation of benzene derivatives, except phenols, is known [1]. On the other hand, electron-rich heterocycles such as ffirans, thiophenes, pyrroles, oxa-zoles, imidazoles, and thiazoles undergo facile inter- and intramolecular arylation with aryl halides. These are called heteroaryl Heck reactions [2]. 

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Reactions of aromatic and heteroaromatic rings are usually only found with highly reactive compounds containing strongly electron donating substituents or hetero atoms (e.g. phenols, anilines, pyrroles, indoles). Such molecules can be substituted by weak electrophiles, and the reagent of choice in nature as well as in the laboratory is usually a Mannich reagent or... 

In this section we discuss theoretical investigations that help us to understand the structures, electronic spectra, and reactions of aromatic and heteroaromatic diazonium ions. 

Another new use for chiral bis(oxazolines) is the Friedel-Crafts reaction of aromatic and heteroaromatic compounds. Jprgensen and co-workers found that the... 

Borodkin GI, Shubin VG (2006) Electrophilic reactions of aromatic and heteroaromatic compounds in ionic liquids. Russian J Org Chem 42 1745—1770... 

A number of reviews and texts whose topics include photochemical reactions of aromatic compounds have been published during the year and will be mentioned here. A new volume of the Organic Photochemistry series has appeared and contains a chapter detailing the photochemical reactions of aromatic and heteroaromatic cations (e.g. cyclopropenlum ions, tropylium ions, pyrilium ions and... 

The Knoevenagel reaction of aromatic and heteroaromatic aldehydes with cyanothioacetamides affords a-cyanothioacrylamides (126), which easily undergo thermal dimerization to 3,4-dihydro-2//-thio-pyrans (127). a-Keto-substituted acrylonitriles are synthesized by condensation of p-keto nitriles with aldehydes or ketones. - Benzoylacetonitrile self-condenses to afford (128), which can be transformed... 

Electrophilic reactions of aromatic and heteroaromatic compounds in ionic liquids 06ZOR1761. 

Reactions of Aromatics and Heteroaromatics 3.3.3 Intermolecular Polyarylation of Ketones... 

Thus, zeolites can be used to catalyze Frieael-Crafts alkylation and acylation reactions of aromatics and heteroaromatics. Here, there are a very great number of reactions from a wide range of industrial and university laboratories the most well known one is the Mobil-Badger process. The chosen examples come from the acylation, of heteroaromatics. 

Catalytic AFC reactions of indoles have attracted considerable attention, and there has been significant progress in this area since 2009. Catalytic AFC reactions of aromatic and heteroaromatic compounds with a-imino esters provide a direct approach to optically pure aryl and heteroaryl glycines. In 2009, You and co-workers realized the AFC reaction of indoles with ethyl glyoxylate imine with 10 mol% of chiral phosphoric acid (S)-13b, affording (3-indolyl)glycine derivatives 28 in excellent yields (85-93%) with up to 87% ee (Scheme 6.11). ... 

Vinylogous aldol-type reaction of aromatic and heteroaromatic aldehydes with silyl dienol ethers 21.115, derived from a,p-unsaturated esters, also proceeded smoothly, furnishing exclusively the y-addition products 21.116 (>99 1) with high enantioselectivity in the range of 82-98%... 

The transition-metal-catalyzed direct alkenylation reactions of aromatic and heteroaromatic substrates accompanied by C-H bond cleavage have been developed significantly in past few decades. These reactions provide powerful tools for preparing a wide range of -conjugated molecules from simple, readily available... 

Sosnovskikh VY, Kutsenko VA (1999) Reactions of aromatic and heteroaromatic p-amino-p-polyfluoroalkylvinyl ketones with ethylenediamine. A new synthesis of N,N -unsubstituted imidazohdines. Russ Chem Bull 48 540-551... 

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