A-Alkylanilines

The mechanism of oxidation (16 —> 17) is not well understood. Both tetrahydroquinoline (19) and A-alkylaniline (20) have been isolated from reaction... 

Therefore in this section we will focus first on the reactions of arenediazonium ions with secondary amines such as A-alkylanilines and dialkylamines. Reactions with primary amines will be discussed later in this section. Most diarylamines do not undergo Af-azo coupling to a significant extent, as they are weaker nucleophiles. 

Difficult N-acylations, such as those of A-alkylanilines or a-alkylamino acid derivatives, are most conveniently performed with acyl halides in non-nucleophilic solvents (e.g. DCM, DCP) in the presence of pyridine or DIPEA [13]. Acyl halides can be prepared on insoluble supports under conditions similar to those used in solution. Typical reagents for the preparation of acyl chlorides include oxalyl chloride [19-21], thionyl chloride [22,23], and triphosgene [13]. Anhydrous solvents must be used for all wash-... 

Of interest is the application of the conjugated dehydrogenation technique to transformations of more complex objects, for example, A-alkylanilines, for /V-cthylaniline dehydrogenation, in particular. Besides illustrating new possibilities of the technique mentioned, all the above would help to solve several theoretical questions associated with A-alkylaniline behavior under reaction conditions. 

The reaction of A-alkylaniline derivatives with aryllead triacetates led to the trisubstituted WalksT/V./V-diaryla-mine in modest yields. For example, arylation of 5-aminoindane (73, R = H) with />-tolyllead triacetate 58 gave the... 

Table 1. Influence of electrolysis conditions on product distribution in the anodic oxidation of aniline and A -alkylanilines. ...

These amidometallocenes do not significantly recognize halides, however, the redox potential shifts being very small [372]. Chloride and bromide were specifically recognized by 24-cationic dendrimers bearing iron sandwich units at the termini of the branches [376, 377]. The sandwich units was [FeCp ( / -A-alkylaniline)]+. 

Aryl-3-chloro-l,2-dithiolium ions react with various secondary amines (morpholine, A-alkylanilines, diarylamines) to give 3-amino-5-aryl-l,2-dithiolium ions (41) which may also be considered as iminium derivatives (42). ... 

Aniline and its derivatives may form three types of products (Scheme 3) If no para-substituent is present, tail-to-tail coupling results in the formation of benzidine derivatives (XIX) anilines and A-alkylanilines also can undergo head-to-tail coupling to give 4-ami-nodiphenylamines (XX) even in the presence of certain / flra-substituents, one of which is eliminated head-to-head coupling forming azo compounds (XXI) is possible with N-unsubstituted anilines. 

A generalized reaction scheme for anilines and A-alkylanilines based on results by Nelson [37] is shown in Scheme 4. 

Table 1 Influence of Electrolysis Conditions on Product Distribution for Anodic Oxidation of Aniline and A-Alkylanilines...

Orthoformates have been reacted with secondary aliphatic aminesj- A -alkylanilines, 1,3.5-triaminocyclohexanes and cyclic triamines to afford trisaminomethane derivatives, e.g. (535) and (536) (Scheme 97), usually in unsatisfactory yields. Better results have been reported when ortho-formates were replaced by amide acetals. - ... 

Preparation of A -alkylanilines from aliphatic Grignard reagents and aryl azides was discussed previously (Eq. 29). The net insertion of a methylene group between the alkyl or aryl group of an organolithium reagent and the nitrogen as part of an animation was also mentioned earlier (Eq. 6). 

The keto tautomer has been isolated in crystalline form for a number of D-fruc-tose-A -alkylanilines and the structure was unequivocally confirmed by IR and solid-state NMR spectroscopic data, " as well as by X-ray diffraction studies. " The ability of D-fructose-A -alkylanilines to crystallize spontaneously in the acyclic keto form is unprecedented among six-carbon reducing carbohydrates, and is matehed only by ribulos- and xylulos-amines, " which themselves are the Amadori rearrangement products. This phenomenon may be explained on the basis of an interplay of the hydrophobic effect and crystal-packing forces, given that many D-fruetose-A -alkylanilines still crystallize in the p-pyranose form, and for the majority of those which crystalhze in the keto form, the acyclic tautomer constitotes a minor eonstituent in equilibrated solutions. 

This reaction was initially reported by Doebner and von Miller in 1881 as a modification of the original Skraup Reaction, and it was subsequently modified by Beyer in 1886 It is an acidic condensation between primary aromatic amines (e.g., anilines) and Q ,j8-unsaturated carbonyl compounds (mostly o ,y3-unsaturated aldehydes) to give 2,3-disubstituted quinolines. Therefore, this reaction is generally known as the Doebner-Miller reaction, or Doebner-Miller synthesis." In addition, this reaction is also referred to as the Doebner-von Miller quinoline synthesis, Skraup-Doebner-von Miller reaction, Skraup-Doebner-von Miller quinoline synthesis, Doebner-Miller condensation, and Doebner-Miller Quinaldine Synthesis. For comparison, the modification from Beyer, known as the Beyer method for quinoline, is an acidic condensation between anilines and Q ,j8-unsaturated carbonyl compounds generated in situ from aldehyde or aldehyde and methyl ketone to afford 2,4-disubstituted quinolines." The optimal condition of this reaction is to heat the mixture of aniline/aldehyde (1 2) at 100°C for 6 h with hydrochloric acid and zinc chloride in addition, an oxidizing reagent is also needed in this reaction, such as nitrobenzene. However, it has been reported that A -alkylanilines are also formed in this reaction. The nature and... 

A range of secondary A-alkylanilines undergo oxidative olefination with 2-alkyl-quinoline, 4-methylquinoline, 1-methylisoquinoline, 2-methylquinoxaline, 2-methyl-quinazoline, 2-methylbenzo[fiG-thiazole, acetophenone, and malononitrile in DMF to form structurally diverse polysubstituted alkenes in moderate to excellent yields with excellent E Z >99 1 selectivity with the use of 2,3-dichloro-5,6-dicyano-l,4-benzoquinone as the oxidant. Mechanistically, the oxidative olefination reaction proceeds through amine oxidation followed by imine olefination." ii... 

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