Substitution disubstituted anilines

Two examples of such applications are outlined in Scheme 3. In the first one imidazolidinone la 10 mol% catalyzed the conjugated addition of a plethora of variously substituted N,N-disubstituted anilines to ,/fun saturated aldehydes to afford highly enantiomerically enriched /3-aryl aldehydes 5 (ee 89-97 %) in good yields (>73 %) [3]. On the other hand, the use of cationic BINAP-Cu complexes 6 (1-5 mol%) was found to be effective in the stereocontrolled 1,2-addition of indoles to the N-tosyl-a-imino ester 7 in TFIF at -78 °C [4]. 

Proton magnetic resonance, infrared spectroscopy and dielectric relaxation measurements, on ortho- and meta-disubstituted anilines, indicate that (despite what is expected on the basis of the usual steric hindrance arguments) a meta-substituted compound such as 32 results in more hindered rotation of the NH2 group than for orf/zo-substituted compounds such as 33. Solute/solvent and solute/solute intermolecular hydrogen bonding interactions are responsible for this hindered rotation73. 

The foregoing discussion has focused upon condensations of non-enolizable aldehydes and ketones to afford green processes and products. That approach was extended to include a one step multicomponent preparation of N-mono-substituted or N,N-disubstituted aniline derivatives (Scheme 6.2). The... 

Quinacridones substituted in the peripheral rings are synthesized by the methods described earlier by including appropriately substituted aniUnes. Anilines that are p- and o-substituted afford 2,9- and 4,11-disubstituted quinacridones, respectively. By contrast, the inclusion of m-substituted aniUnes afford intermediate terephtha-lic acids that possess two distinct sites that compete for cyclization, subsequently resulting in the formation of the three possible isomers 3,10-, 1,8- and 1,10-disub-stituted quinacridones. The 3,10-isomer predominates in the mixture because it is formed by cyclization at the least stericaUy hindered sites of the intermediate product. In some instances, the three isomers can be separated. The individual compounds also can be distinguished by inspection of the NMR spectra of the mixtures [36]. Like the parent compound, many of the substituted derivatives, including 6,13-dihydroquinacridone [37], exhibit polymorphism For example,... 

Alen et al. (2008) reported a reaction of 3,5-dichloropyrazinones with 2-bro-mo-4,6-disubstituted aniline to give 3-anilino-pyrazinones. A microwave-assisted Buchwald-Hartwig type cyclization converted various 3-anilino-pyrazinones easily to the substituted pyrazino[l,2-a]benzimidazol-l(2/0ones (tricyclic stmctures) using palladium as catalyst with moderate to good yield (27-78%). 

FrielA,nderSynthesis. The methods cited thus far all suffer from the mixtures which usually result with meta-substituted anilines. The use of an ortho-disubstituted benzene for the subsequent constmction of the quinoline avoids the problem. In the FrieWider synthesis (52) a starting material like 2-aminoben2aldehyde reacts with an CX-methyleneketone ia the presence of base. The difficulty of preparing the required anilines is a limitation ia this approach, but 2-nitrocarbonyl compounds and the subsequent reduction of the nitro group present a usehil modification (53). 

Because of the structural requirements of the bielectrophile, fully aromatized heterocycles are usually not readily available by this procedure. The dithiocarbamate (159) reacted with oxalyl chloride to give the substituted thiazolidine-4,5-dione (160) (see Chapter 4.19), and the same reagent reacted with iV-alkylbenzamidine (161) at 100-140 °C to give the 1 -alkyl-2-phenylimidazole-4,5-dione (162) (see Chapter 4.08). Iminochlorides of oxalic acid also react with iV,iV-disubstituted thioureas in this case the 2-dialkylaminothiazolidine-2,4-dione bis-imides are obtained. Thiobenzamide generally forms linear adducts, but 2-thiazolines will form under suitable conditions (70TL3781). Phenyliminooxalic acid dichloride, prepared from oxalic acid, phosphorus pentachloride and aniline in benzene, likewise yielded thiazolidine derivatives on reaction with thioureas (71KGS471). 

Reaction of 2,4-dichloro-l,5-naphthyridine with ammonia (170°, 20 hr), hydrazine (100°, 16 hr), or aqueous hydrochloric acid (100°, 3 hr) was shown to yield the 2-amino- (47% yield) and 2-hydroxy-4-chloro derivatives (66% yield), but 2-hydrazino substitution (68% yield) was assumed. Disubstitution with ammonia (190°, 4 hr), hydrazine (100°, 48 hr), and ammonia-phenol (180°, 6 hr) occurred in high yield. Displacement of the 4-oxo group in 2,4-dioxo-l,5-naphthyridine occurs with aniline plus its hydrochloride (180°, 12 hr, 88% yield) to yield 429. Oxo groups in the 2- or 4-positions were... 

Complexity in the manganese and rhenium pentarbonyl halides substitution arises from the fact that these decompose in inert solvents to form the halogen-bridged dimers [M(CO)4X]2. Both monomers and dimers react with phosphines, arsines, pyridine, aniline etc. to give the disubstituted compounds M(CO)3XL2. Thus three final products or any mixture of them may be obtained, depending upon the precise reaction conditions... 

Reaction of 165 with neutral nucleophiles such as aniline leads to disubstitution of the PC12 group but with no further substitution. Sterically undemanding charged nucleophiles replace all the three chlorines (Scheme 20) <2004CEJ4915>. 

A striking feature of disperse dye development in recent decades has been the steady growth in bathochromic azo blue dyes to replace the tinctorially weaker and more costly anthraquinone blues. One approach is represented by heavily nuclei-substituted derivatives of N,N-disubstituted 4-aminoazobenzenes, in which electron donor groups (e.g. 2-acylamino-5-alkoxy) are introduced into the aniline coupler residue and acceptor groups (acetyl, cyano or nitro) into the 2,4,6-positions of the diazo component. A PPP-MO study of the mobility of substituent configurations in such systems demonstrated that coplanarity of the two aryl rings could only be maintained if at least one of the 2,6-substituents was cyano. Thus much commercial research effort was directed towards these more bathochromic o-cyano-substituted dyes. 

The ability to adopt an extended configuration has been recognised for many years to be a desirable feature of substantive dyes. It helps to explain why J acid is such a popular choice as a central component in unsymmetrical disazo dyes. For example, it is much easier for aniline—>] acid—>H acid (3.61) with the 2,6-naphthylene substitution pattern to adopt a linear conformation than for the similar disazo dyes aniline—acid— H acid (3.62) and aniline—>H acid—>J acid (3.63) with 2,7- and 2,8-disubstitution respectively. 

Succinylosuccinic diester is cyclized according to the common route by using chlorinated or methylated aniline. Starting from anilines which are substituted in 2- or 4-position, the reaction affords the symmetrical 4,11- or 2,9-disubstitution products. Reaction with 3-substituted anilines, on the other hand, produces a mixture of both of the symmetrical 1,8- and 3,10-disubstitution products, as well as un-symmetrical 1,10-disubstituted compound. The following chart illustrates this point. 

The most frequent application of Larock s method is undoubtedly the conversion of o-haloanilines to indoles. The scope of this transformation covers a wide range of disubstituted acetylenes and anilines including both TV-substituted and unsubstituted derivatives. A schematic representation of... 

The presence of a fluorine or a chlorine atom on the aromatic ring clearly leads to two different behaviors, giving two different products—aniline-1- or anilinium ion with formation of HX or X. Apparently, two different reaction coordinates are involved. In disubstituted aromatic compounds, depending on the nature of the substitutents, these two processes are competitive. 

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