Carbonates reaction with aromatic amines

The JV-chloroethylphosphazene CCl3CCl2N=PCl3 generally undergoes reactions with aromatic amines at both phosphorus and a-carbon atoms ... 

Nucleophilic displacement of chlorine, in a stepwise manner, from cyanuric chloride leads to triazines with heteroatom substituents (see Section 6.12.5.2.4) in symmetrical or unsymmetrical substitution patterns. New reactions for introduction of carbon nucleophiles are useful for the preparation of unsymmetrical 2,4,6-trisubstituted 1,3,5-triazines. The reaction of silyl enol ethers with cyanuric chloride replaces only one of the chlorine atoms and the remaining chlorines can be subjected to further nucleophilic substitution, but the ketone produced from the silyl enol ether reaction may need protection or transformation first. Palladium-catalyzed cross-coupling of 2-substituted 4,6-dichloro-l,3,5-triazine with phenylboronic acid gives 2,4-diaryl-6-substituted 1,3,5-triazines <93S33>. Cyanuric fluoride can be used in a similar manner to cyanuric chloride but has the added advantage of the reactions with aromatic amines, which react as carbon nucleophiles. New 2,4,6-trisubstituted 1,3,5-triazines are therefore available with aryl or heteroaryl and fluoro substituents (see Section 6.12.5.2.4). 

Cyanuric fluoride behaves much the same as cyanuric chloride but its higher reactivity leads to nucleophilic reactions with aromatic amines, which act as carbon nucleophiles. This is a useful advantage for cyanuric fluoride, as a synthetic reagent, for the synthesis of these triazine derivatives with carbon substituents. 

Aromatic amines are usually very reactive towards electrophilic reagents yielding derivatives substituted at carbon atoms. Reactions such as nitration and bromination can be applied to the amine as such, or to the amine previously protected at the nitrogen site. Although the derivatives from these reactions are useful for identification and possibly quantitative purposes, the site and stoichiometry of the substitution are specific for every system, and no generalisation can be made. Aryldiazonium salts undergo coupling reactions with aromatic amines to yield azo dyes, which can be used for detection and determination. In Table 12 some of the aryldiazonium salts used in analysis are listed. 

Sugars such as glucose and mannose have been analyzed by condensing the oxygen of the anomeric carbon atom with aromatic amines to form water. Koshland and Stein (1954) heated glucose with an excess of p-phenylene diamine for 15 minutes at 150°C., and Halpern and Leibowitz (1959) heated mannose with wi-phenylene diamine at 97°C. The water formed is distilled off and equilibrated with COj in the usual manner. Small corrections are required owing to the occurence of side reactions with other oxygen atoms. 

The reactivity of these group 4 metal complexes has been studied to some extent. Starting from complex [(6)MCl2], the reaction with nucleophiles such as alkylhthium led to the classical reactivity at M-Cl (Scheme 32) [89]. The reactions with strong electrophiles such as isocyanates, carbon dioxide, or carbodiimide did not show the expected insertion into the M=C bond, but rather a [2+2] cycloaddition. The basicity and nucleophilicity of the C center was proved by reactions with aromatic amines, phenols, aliphatic alcohols, or methyl iodide leading to the 1,2 addition product. 

A halogen atom directly attached to a benzene ring is usually unreactive, unless it is activated by the nature and position of certain other substituent groups. It has been show n by Ullmann, however, that halogen atoms normally of low reactivity will condense with aromatic amines in the presence of an alkali carbonate (to absorb the hydrogen halide formed) and a trace of copper powder or oxide to act as a catalyst. This reaction, known as the Ullmant Condensation, is frequently used to prepare substituted diphenylamines it is exemplified... 

As previously discussed, activation of the iridium-phosphoramidite catalyst before addition of the reagents allows less basic nitrogen nucleophiles to be used in iridium-catalyzed allylic substitution reactions [70, 88]. Arylamines, which do not react with allylic carbonates in the presence of the combination of LI and [Ir(COD)Cl]2 as catalyst, form allylic amination products in excellent yields and selectivities when catalyzed by complex la generated in sim (Scheme 15). The scope of the reactions of aromatic amines is broad. Electron-rich and electron-neutral aromatic amines react with allylic carbonates to form allylic amines in high yields and excellent regio- and enantioselectivities as do hindered orlAo-substituted aromatic amines. Electron-poor aromatic amines require higher catalyst loadings, and the products from reactions of these substrates are formed with lower yields and selectivities. 

Catalytic amounts of tin(II) chloride have been found to give good yields (72-86%) of the trans-amino alcohols when oxiranes have been treated with aromatic amines in acetonitrile at room temperature.27 Only the reaction with styrene oxide was regiospe-ciflc with the amine adding to the benzylic carbon of the epoxide ring. 

Several catalysts have been found for the ring opening of epoxides. For instance, cyclohexene oxide gave an excellent yield of the trans-fi-amino alcohol when treated with either aromatic or aliphatic amines in the presence of a scandium triflate catalyst.21 Aromatic epoxides react in a regiospeciflc reaction at the benzylic carbon when treated with aromatic amines and scandium triflate but at the least substituted carbon of the epoxide ring when aliphatic amines react. Electronic effects are more important in the reactions of the aromatic epoxides whereas steric factors control the reaction with aliphatic epoxides. 

We have used organo-phosphorus acids [25] as promoters of the reaction of aromatic amines with dimethylcarbonate (DMC) or diphenylcarbonate (DPC) in the presence of carbon dioxide to generate N-alkyl- or aryl-carbamates. We have applied this methodology to the carbamation of aniline, naphtylamine, toluen-diamine, 4,4 -diaminophenyl-methane, among others. 

From a theoretical point of view this is an extremely interesting reaction. The displacement of a hydroxyl group from a saturated carbon atom appears to be unknown in basic solution. The fact that amino-methane sulfonic acid can be isolated from the bisulfite addition product of formaldehyde on treatment with ammonia does not prove, of course, that a direct displacement, such as is indicated in XVI to XVII, actually occurred. Furthermore, it is quite clear that preliminary formation of an imine (XVIII) is not necessary for the reaction of aromatic amines with sodium bisulfite (steps XIX to XVIII to XVII, etc.). 1-Dimethyl-aminonaphthalene-4-sulfonic acid (XX) and l-aminonaphthalene-4-sulfonic acid (XIX) show similar reaction kinetics 16a when treated with sodium bisulfite, yet with the tertiary amine (XX) it is not possible to write an imino structure corresponding to XVIII. 

Reaction with phosphorus oxychloride 806 Carbon disulfide (18 ml, 0.3 mole) is dropped into a stirred solution of an amine (0.3 mole) and anhydrous triethylamine (126 ml, 0.9 mole) in anhydrous ether (150 ml) at —5° with aromatic amines the mixture is set aside overnight. Then a solution of phosphorus oxychloride (28 ml, 0.3 mole) in anhydrous ether (30 ml) is dropped in, with stirring, at —10° to —5°. Next day the precipitated triethylammonium chloride is filtered off and stirred thoroughly with two portions of ether. The ethereal solutions are extracted with sodium hydrogen carbonate solution and with water, dried over sodium sulfate, concentrated, and fractionated. Yields are about 60%. 

A great deal of carbanirms, generated from C-H-active compounds, the Grignard reagents, the cyanide ion, all kinds of organometallic carbon-lithium derivatives, aromatic amines, phenols, pyrroles, indoles, thiophenes, furans, and other organic compounds with electron-rich carbon atoms have been involved in the Sn reactions as C-nucleoplules [1, 2, 10, 11, 114—117]. 

Addition of an ammonia source to pyrylium salts readily affords pyridine derivatives and provides a good method for the preparation of the pyridine moiety if the corresponding pyrylium salt is accessible. The carbon oxygen double bond present in the pyrylium salt is an oxonium ion however, owing to aromatic stabilization they are easily formed by a variety of methods. The reactivity of pyrylium salts toward nucleophiles makes them useful reagents for the preparation of structurally diverse heterocyclic compounds. Thus pyrylium salts afford pyridines by reaction with ammonia, pyridine-A -oxides by reaction with hydroxylamine and pyridinium salts by reaction with primary amines. 

In 1993, Corriu et al. studied the synthesis of nitrogen-containing heterocycles from (Z)-3-(tribulylstannyl)allylamine, which was prepared by the reaction of Af-(trimethylsilyl)allylamine with 2 mol of ra-butyllithium followed by treatment with chlorotributyltin and subsequent hydrolysis. The unprotected (Z)-3-(tributylstannyl)allylamine underwent a palladium-catalyzed cross-coupling reaction with aromatic bromides affording a stereospecific preparation of substituted allylic amines with Z configuration of the carbon-carbon double bond. The reactions of o/t/zo-functionalized aryl bromides offer a one-step preparation of 7-membered nitrogen heterocycles in high yields (Scheme 4.18). 

There has been a review commentary of substitutions in non-polar media addressing the question, are weak interactions responsible for kinetic catalytic behaviour in 5 NAr reactions A kinetic study of the reactions of picryl fluoride with alcohols in carbon tetrachloride shows that the order in alcohol is greater than unity. This is interpreted as evidence for specific interaction between the substrate and alcohol prior to rate-limiting reaction with a further alcohol molecule. Self-association of amine molecules to form dimers which act as the effective nucleophile is an alternative explanation for the high kinetic orders observed in non-polar solvents. Results for the reaction of l-chloro-2,4-dinitrobenzene with aromatic amines in toluene - " and in benzene-hexane mixtures have been interpreted on this basis. Rate constants have been measured for reactions of l-halo-2,4-dinitrobenzenes with primary and secondary amines in a variety of aprotic binary solvent systems and correlations have been attempted with solvatochromic data, including t(30) values. ... 

Carboxyhc acids react with aryl isocyanates, at elevated temperatures to yield anhydrides. The anhydrides subsequently evolve carbon dioxide to yield amines at elevated temperatures (70—72). The aromatic amines are further converted into amides by reaction with excess anhydride. Ortho diacids, such as phthahc acid [88-99-3J, react with aryl isocyanates to yield the corresponding A/-aryl phthalimides (73). Reactions with carboxyhc acids are irreversible and commercially used to prepare polyamides and polyimides, two classes of high performance polymers for high temperature appHcations where chemical resistance is important. Base catalysis is recommended to reduce the formation of substituted urea by-products (74). 

Environmental Impact of Ambient Ozone. Ozone can be toxic to plants, animals, and fish. The lethal dose, LD q, for albino mice is 3.8 ppmv for a 4-h exposure (156) the 96-h LC q for striped bass, channel catfish, and rainbow trout is 80, 30, and 9.3 ppb, respectively. Small, natural, and anthropogenic atmospheric ozone concentrations can increase the weathering and aging of materials such as plastics, paint, textiles, and mbber. For example, mbber is degraded by reaction of ozone with carbon—carbon double bonds of the mbber polymer, requiring the addition of aromatic amines as ozone scavengers (see Antioxidants Antiozonants). An ozone decomposing polymer (noXon) has been developed that destroys ozone in air or water (157). 

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