A -substituted anilines

The Gassman indole synthesis involves an one-pot process in which hypohalite, a P-carbonyl sulfide derivative 2, and a base are added sequentially to an aniline or a substituted aniline 1 to provide 3-thioalkoxyindoles 3. Raney nickel-mediated desulfurization of 3 then produces the parent indole... 

Substituted thioindigoid dyes are usually obtained via the appropriate benzenethiol in a Heumann-type synthesis. The final cyclisation of the phenylthioglycolic acid derivative can often be achieved in concentrated sulphuric acid or by using chlorosulphonic acid. Several routes make use of the Herz reaction (Scheme 6.22), in which a substituted aniline is converted into the corresponding o-aminothiophenol by reaction with sulphur monochloride followed by hydrolysis of the intermediate dithiazolium salt [47]. After reaction between the thiol and chloroacetic acid, the amino group is converted into a nitrile group by a Sandmeyer reaction. Hydrolysis of the nitrile leads to the formation of the required thioindoxyl derivative. 

Quinolines (2-substituted) Quinolines (8-substituted) a-Naphthylamines /TNaphthylamines Benzylamines (ring substituted) A-Substituted anilines 1 -Aminoanthracene ... 

The most general method for synthesizing quinolines employs aniline or a substituted aniline, glycerol, sulfuric acid, and an oxidizing agent such as a ferric... 

Two additional examples of amine nomenclature are shown in Figure 13-6. Note that in the p-aminobenzoic acid the oxygen-containing group takes precedence in the naming, so that the compound is then named as a substituted benzoic acid and not a substituted aniline, as is done in the N,N-dimethylaniline beside it. 

Since many W-nitrosoaniline derivatives are liquids, suitable modifications have to be made for the isolation of the product. In many cases the nitrosation is carried out with a dispersion of A-substituted anilines in hydrochloric acid and crushed ice to maintain the low temperatures of the reaction. Concentrated hydrochloric acid and sodium nitrite solutions are then added in turn while maintaining temperatures between 0° and 10°C. The product may be isolated by extraction with suitable solvents, such as benzene [26] or ether [27, 28], followed by evaporation of the solvent and distillation of the product under reduced pressure. 

The stereochemistry of the cobalt(II) chloride-catalysed opening of cinnamoyl epoxides with A-substituted anilines is controlled by the para substituent of the aromatic ring.36 Thus / -OMe promotes cleavage giving the anti ammo alcohol as the... 

For the preparation of biphenyl compounds with substituents in only one ring, it is usually advisable to employ a substituted aniline and couple with benzene rather than to use aniline and couple with a benzene derivative, since with benzene only a single biaryl compound is produced. Thus, 4-methylbiphenyl can be isolated readily in pure form from the reaction between diazotized p-toluidine and benzene, but not from the mixture of 2- and 4-methylbiphenyl formed from diazotized aniline and toluene. 

A route to a Fischer s base (21) useful in some cases involves the oxidation with mercuric acetate of its reduced form, a 1,2,3,3-tetra-substituted indohne (20). Since the indoline is merely a substitute aniline it may be more efficient to prepare this intermediate. A number of examples are presented in Scheme 13. 

The reaetion of amines with 2,4-dinitrophenyl sulfate can result in the formation of phenol and sulfate ion (by S—O bond fission), or alternatively in the production of A-substituted anilines and hydrogen sulfate ions (by C—O bond fission). Under non-micellar conditions, C—O bond cleavage is the dominating reaetion, while eationie micelles are able to induce complete suppression of aniline formation. This dramatie effect has been explained in terms of a change in the miero-environment of both the reactants and activated complexes through contributions from hydrophobic and electrostatic interactions [407]. 

EPR was stabilized by azomethine dyes [168] by rolling them at 160 °C for 5 h under pressure. Smith et al. [169] have found that these dyes function as quenchers of O2. The azomethine derivatives may be considered as a-substituted anilines... 

The chemistry of amines is dominated by the lone-pair electrons on nitrogen, which makes amines both basic and nucleophilic. The base strength of arylamines is generally lower than that of aliphatic amines because the nitrogen lone-pair electrons are delocalized by interaction with the aromatic tt system. Electron-withdrawing substituents on the aromatic ring further weaken the basicity of a substituted aniline, while electron-donating substituents increase basicity. 

The short and convenient synthesis of novel naphthopyranoquinolines from naphthopyran chloroaldehydes via the Doebner-Miller synthesis was developed in the laboratory of J.K. Ray. The chloroaldehydes were treated with 2.5 equivalents of a substituted aniline in ethanol in the presence of 2N HCI to afford enaminoimine hydrochlorides in good yield. These hydrochloride salts were exposed to heat at a temperature slightly above their melting point, resulting in ring-closure and elimination of one equivalent of arylamine hydrochloride. 

FIGURE 27. A histogram of number of occurrences (N) for angle (A9) value in A-substituted anilines. The number of observations, minimum, maximum, mean and median angles, skewness, mean SE and sample SD are given in the following order 1135, 89.713, 139.437, 116.915, 116.860, -0.220, 0.128, 4.324... 

A more detailed analysis has been performed for ring-2,6-disubstituted A-substituted anilines. In these molecules there are possibilities for interactions between a proton on the amino group and a substituent in the ortho-position. A total of 106 crystal structures have been retrieved from the CSD. Frequency histograms of bond and angle values are shown in Figure 29. 

Figure 2. The gel (%) and polymerization (O) times of unsaturated polyester containing a fixed initial concentration (in mol/L) of benzoyl peroxide and aryl-substituted N,N-bis(3-allyloxy-2-hydroxy-propyl)aniline versus the (t+ value of the aryl substituent of the amine. The symbols (A, A) indicate the corresponding time values for the analogous N-substituted 2-naphthylamine which in the usual sense is not a substituted aniline. (Time values from Refs. 24 and 25 (t+ from Ref. 23, except for (t+ value for 2-naphthyl (—0.61), recalculated from Bier (64).)...

An interesting example of a formal [4 + 2]-cycloaddition has been found to occur on condensing A-substituted anilines with co-unsaturated aldehydes in the presence of Lewis Acids. In this study, A-phenylamines 162 underwent condensation with 163 to provide acridine products 165 in ca. 60-75% yields (Scheme 29) (96CC1213). The intermediate iminium ions 164 that are first formed either participate in a concerted [4 + 2]-cycloaddition (followed by proton transfer) or else undergo polar addition to the pendant alkene by addition of the resultant benzylic carbocation onto the aniline ring. 

When l-dicyanomethylene-3-indanone was treated with trimethyl ortho formate and a substituted aniline in the presence of AcOH it gave anilinomethylene-indanone 99 followed by ring closure and Dimroth rearrangement to indanopyridine 100 (89M781) (Scheme 31). 

A diastereoselective synthesis of azetidines 16 (12 examples with yields in the range (62-82%) by decomposition of azazirconacyclopentanes 15 with iodine is reported <97JOC5953>. The intermediate 15 can be obtained in a zirconium-mediated reaction of A-substituted anilines 14 with an olefin. 

Another recent example (Ford and Conner, 1994) is the alkylation of aniline or a substituted aniline with /j-isopropenylaniline (28) to give bisaniline A (29) with potential applications in polyamides, polyimides, and as a component in epoxy systems. 

The great majority of quinolines and isoquinolines have been prepared by ring construction, instead of transformation of preexisting derivatives. They are obtained by variants of two main routes. The first route involves the cyclization of mono-substituted benzene rings, usually A-substituted anilines (Skraup, Doebner-von Miller, Knorr, Conrad-Limpach), and the second route involves the intramolecular condensation of o-disubstituted benzenes for the formation of the requisite pyridine ring (Friedlander, Pfitzinger reaction, etc.). 

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