Amination arenes

The photolysis of donor-acceptor systems shows a reaction pattern of unique synthetic value. Direct irradiation of the donor-acceptor pairs, such as arene-amine, leads by intramolecular electron transfer, to amine radical cations and arene radical anions. The generated radical cation and radical anion intermediates undergo cyclization reactions providing efficient synthetic routes to N-heterocycles with a variety of ring sizes. 

Further investigations on the acceptor-donor system arene-amine have been made by Sugimoto et al. They have reported that direct irradiation of 9-(cu-anilinoalkyl)phenanthrenes give spirocyclic pyrroline derivatives, invoked by... 

In addition, aryl chlorides, bromides, and iodides can be converted to arene-amines ArNH2 by the conjugate bases of amines. In fact, the reaction of potassium amide with bromobenzene is extremely rapid, even at temperatures as low as —33°, with liquid ammonia as solvent ... 

As with arene-amine radical ion pairs, the ion pairs formed between ketones and amines can also suffer a-deprotona-tion. When triplet benzophenone is intercepted by amino acids, the aminium cation radical can be detected at acidic pH, but only the radical formed by aminium deprotonation is detectable in base (178). In the interaction of thioxanthone with trialky lamines, the triplet quenching rate constant correlates with amine oxidation potential, implicating rate determining radical ion pair formation which can also be observed spectroscopically. That the efficiency of electron exchange controls the overall reaction efficiency is consistent with the absence of an appreciable isotope effect when t-butylamine is used as an electron donor (179). 

Ozonium Ion (H03+). Ozone is a resonance hybrid of canonical structures 50a-50d.135 Ozone does in fact act as a 1,3-dipole—that is, either as an electrophile or a nucleophile. The electrophilic nature of ozone has been recognized for a long time in its reactions with alkenes, alkynes, arenes, amines, phosphines,... 

H-Azepin 5-Brom-2-diethylamino-E16c, 199 (Nitro-aren/Amin) Malonsaure... 

H-Azepin 3-Cyclopropyl-2-diethyl-amino- E16c, 198 (Nitro-aren/ Amin)... 

After reading this section, you too will know how to recognize and describe alkanes, ethers, carboxylic acids, aldehydes, esters, arenes, amines, and other types of organic compounds. 

Further investigations on the acceptor-donor arene-amine system have been made. Direct irradiation of 9-(co-anilinoalkyl)phenanthrenes give spirocyclic pyrrolidine derivatives by NH addition to the phenanthrene C(9)-C(10) bond [19]. 

The 1980s witnessed a revival of interest in synthetic photochemistry, largely based on the successful application of intramolecular arene-olefin and enone-olefin photochemical cycloaddition reactions to the synthesis of polycyclic natural and unnatural products. The potential application of intramolecular arene-amine addition to the synthesis of alkaloids was suggested in 1973 by Btyce-Smith et al.," based on their observation of intramolecular photochemical 1,4-addition reaction of the (N,A/-dimethylaminoalkyl)benzenes I and 2 to yield 3 and 4, respectively. Intramolecular addition reactions have subsequently been observed for a large number of (aminoal-... 

Our investigation of the mechanism of intramolecular adduct formation employed the technique of arene-amine exciplex quenching by primary amines, which had been developed in earlier investigations of exciplex quenching. These experiments provided evidence for the occurrence of adduct formation via proton transfer in the fluorescent exciplex. In the case of 39, activation parameters for exciplex formation and proton... 

An alternate approach to ET-sensitized intramolecular arene-amine addition is being explored by Jung and Mariano. Di-cyanoanthracene (DCA)-sensitized irradiation of the... 

Alkyne replacements have also been reported. In 2008, Sakai et al. described the use of alkynylsilanes instead of terminal alkynes in the Cu-catalyzed synthesis of propargyl-amines, which was applicable to both secondary and primary aliphatic amines, although the latter afforded the corresponding products in low yield [145]. Very recently. Van der Eycken et al. applied the A -coupling to the C—H alkylation of azoles through a copper-catalyzed hetero-arene-amine-aldehyde/ketone coupling [146]. This reaction is proposed to proceed through the initial condensation of... 

It should be added that (2-ethinyl)chlorobenzenes 93 can be converted directly and efficiently to 1,2-disubstituted indoles 95 by reaction with primary amines in a sequential Pd-catalyzed arene amination/cyclization protocol [178]. The intermediately formed (2-ethinyl)anilines 94 need not be isolated. 

Arene Amination. Alternative methods for the A-arylation of N-H-containing heterocycles that proceed directly with arenes (i.e., where aryl halides are not required) have emerged in the literature. In a recently reported procedure, a succinimide derivative was iV-arylated using palladium acetate as the catalyst, tri-ferf-butylphosphine as the ligand, and (diacetoxyiodo)benzene as a stoichiometric oxidant. This reaction allows the formation of ster-ically controlled products with monosubstituted arenes, yielding mainly meta- and / ara-arylated products and di- and trisubsti-tuted arenes, mostly providing the products of arylation at the meta-position (eq 15). ... 

Key words p-lert-Butylcalix[n]arenes, amines, thermodynamics, electrochemistry. 

Although we have now completed a thermodynamic study on amine-p-tert-butylcalix[n]arene (n = 6, 8) in nitrobenzene, in the remaining part of this paper we address new issues related to p-te/t-butylcalix[4]arene-amine interactions in benzonitrile and in nitrobenzene. 

Like amines, dienes quench many arene singlet and triplet states, a process attributed to the formation of diene/arene exciplexes these have a much smaller degree of electron transfer than the corresponding arene-amine exdplexes. Ambiguity arises because dienes are commonly used as triplet quenchers and because simple arenes such as benzenes, naphthalenes, and biphenyls absorb at the same wavelengths as dienes. ... 

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