Aldehydes, reaction with aromatic amines

An acidic solution of 2,4-dinitrophenylhydrazine reacts with N-p-chlorophenyl-sulfonyl-3-ethoxy-l,2-thiazetidine 1-oxide to give (80%) the bis-2,4-dinitrophenyl-hydrazone of glyoxal. The adduct of A-sulfinyl-p-chlorophenylsulfonamide with dihydropyran is inert to catalytic hydrogenation and bromination. Treatment of two l,2-thiazetidine-3-one 1-oxides (e.g., 421) with hydriodic acid results in ring-cleavage and loss of sulfur. They are not oxidized to 1,1-dioxides by peracetic acid, ° but m-chloroperbenzoic acid accomplishes this oxidation. The unstable adducts with ketene decompose to amides with loss of hydrogen sulfide and sulfur dioxide or may be trapped by reaction with aromatic amines as shown for thiazetidine 1-oxide 422.An aldol-type condensation has been reported for A -cyclohexyl-1,2 thiazetidine-3-one 1-oxide and p-(A(A"-dimethylamino)benz-aldehyde. " Sulfur monoxide is lost in the flash-vacuum thermolysis of 422a. ... 

An alternative approach to site-specific introduction of photonic probes relies on the selective oxidation of iV-terminal serine or threonine to an aldehyde followed by specific reaction with aromatic amines or hydrazine derivatives (hydrazides, thiosemicarbazide). Ketone moieties can also be generated by metal-catalyzed transamination reaction. ... 

SchifT s bases A -Arylimides, Ar-N = CR2, prepared by reaction of aromatic amines with aliphatic or aromatic aldehydes and ketones. They are crystalline, weakly basic compounds which give hydrochlorides in non-aqueous solvents. With dilute aqueous acids the parent amine and carbonyl compounds are regenerated. Reduction with sodium and alcohol gives... 

Condensation. Depending on the reaction conditions, a variety of condensation products are obtained from the reaction of aromatic amines with aldehydes, ketones, acetals, and orthoformates. 

Tu found that when aniline was used instead of the secondary amine under otherwise identical conditions 2,4-diphenyl-substituted quinoline was formed in 56% yield. Phenylacetylene and aniline were initially used as model substrates for exploring the aldehyde scope. With aromatic aldehydes the reactions proceeded smoothly to give the corresponding quinolines in moderate to good yields. A heteroaromatic aldehyde is also compatible with this transformation and the expected product was afforded in 83% yield. However, when ahphatic aldehydes were subjected to the reaction, the desired product was obtained in low yield (Scheme 19) [34]. 

Electrophilic substitution of the ring hydrogen atom in 1,3,4-oxadiazoles is uncommon. In contrast, several reactions of electrophiles with C-linked substituents of 1,3,4-oxadiazole have been reported. 2,5-Diaryl-l,3,4-oxadiazoles are bromi-nated and nitrated on aryl substituents. Oxidation of 2,5-ditolyl-l,3,4-oxadiazole afforded the corresponding dialdehydes or dicarboxylic acids. 2-Methyl-5-phenyl-l,3,4-oxadiazole treated with butyllithium and then with isoamyl nitrite yielded the oxime of 5-phenyl-l,3,4-oxadiazol-2-carbaldehyde. 2-Chloromethyl-5-phenyl-l,3,4-oxadiazole under the action of sulfur and methyl iodide followed by amines affords the respective thioamides. 2-Chloromethyl-5-methyl-l,3,4-oxadia-zole and triethyl phosphite gave a product, which underwent a Wittig reation with aromatic aldehydes to form alkenes. Alkyl l,3,4-oxadiazole-2-carboxylates undergo typical reactions with ammonia, amines, and hydrazines to afford amides or hydrazides. It has been shown that 5-amino-l,3,4-oxadiazole-2-carboxylic acids and their esters decarboxylate. 

Sano et al. have reported the synthesis of the 2-benzazepines 266. The steps involved reaction of the aromatic aldehydes 260 with the amine 261 to give the imines 262, followed by reduction to the amines 263, N-formylation to 264, and oxidation to the corresponding sulfoxides 265 (Scheme 34). The seven-membered ring was then formed by a modified Pummerer reaction on 265, which was then used to complete the seven-membered ring in yields ranging from 45% to 78% (e.g., 266 R1 = R2 = H, R3 = OMe, R4 = H 78%) <2001H(54)967>. 

Oximes and Hydrazones.—The characteristic aldehyde and ketone reactions with hydroxyl amine and phenyl hydrazine, depending upon the carbonyl group, = C = O, take place with the aromatic aldehydes and ketones just as they do with the aliphatic and yield oximes and hydrazoneSy the former being of especial importance. 

The synthetic utility of benzotriazole derivatives as >N—C< >N=C< synthons has been explored by Katritzky and his coworkers. The Mannich reaction of benzotriazole with primary aliphatic amines RNH2 and formaldehyde in an aqueous medium results in the formation of one or more of three types of product BtCH2NHR, (BtCH2)2NR and (BtCH2NR)2CH2 [Bt = benzotriazol-l-yl (93)]. Benzotriazole and aliphatic or aromatic aldehydes yield compounds 94. The parent compound 1-hydroxymethylbenzotriazole reacts with aromatic amines to give secondary amines 95, primary aliphatic amines give the tetiary amines 96 and aqueous ammonium acetate at room temperature yields 97. The 1-benzotriazoles 98 are obtained from benzotriazole, aldehydes and aromatic amines ... 

Their reaction setup requires the conversion of aldehyde 122 and aromatic amine 123 into the imine prior to treatment with catalyst 99c (a phosphoric acid) and enecarbamate (and a final reduction of the hemiaminal intermediate 125). This three-component reaction can thus be classified as a sequential reaction. Notably, the authors also used aliphatic aldehydes successfully. Using substituted enecarbamates gave 1,2-disubstituted 1,3-diamines 126 with excellent anti-selectivity. They proposed a transition state in which the chiral phosphoric acid activates not only the imine as a Bronsted acid, but also the (i )-enecarbamate as Bronsted base, resulting in a pseudo-intramolecular Si-face attack to the imine [69]. 

Doebner-von Miller reaction Condensation of an aromatic amine with an aldehyde or ketone in the presence of hydrochloric acid to form a quinoline derivative. A general method, thus aniline and ethanal give 2-methyl-quinoline (quinaldine) and p-phenetidine. 

Leuckart reaction The conversion of ketones and aromatic aldehyde,s to primary amines by reaction with ammonium methanoale at a high temperature. 

Quinoline derivatives may be synthesised by heating aii aromatic amine with an aldehyde or a mixture of aldehydes in the presence of concentrated hydrochloric or sulphuric acid this synthesis is known as the Doebner - Miller reaction. Thus aniline and paraldehyde afford 2-methylquinohne or quinaldine. 

This is an example of the Doebner synthesis of quinoline-4-carboxylic acids (cinchoninic acids) the reaction consists in the condensation of an aromatic amine with pyruvic acid and an aldehj de. The mechanism is probably similar to that given for the Doebner-Miller sj nthesis of quinaldiiie (Section V,2), involving the intermediate formation of a dihydroquinoline derivative, which is subsequently dehydrogenated by the Schiff s base derived from the aromatic amine and aldehyde. 

Primary aromatic amines react with aldehydes to form Schiff bases. Schiff bases formed from the reaction of lower aUphatic aldehydes, such as formaldehyde and acetaldehyde, with primary aromatic amines are often unstable and polymerize readily. Aniline reacts with formaldehyde in aqueous acid solutions to yield mixtures of a crystalline trimer of the Schiff base, methylenedianilines, and polymers. Reaction of aniline hydrochloride and formaldehyde also yields polymeric products and under certain conditions, the predominant product is 4,4 -methylenedianiline [101 -77-9] (26), an important intermediate for 4,4 -methylenebis(phenyhsocyanate) [101-68-8], or MDI (see Amines, aromatic amines, l thylenedianiline). 

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