P-Aminocrotonic acid

Condensation of the TV-substituted p-aminocrotonic acid ester 15 with p-benzoquinone (4) has been successfully carried out to furnish the 5-hydroxyindole 29 when the substituent R on the nitrogen of the aminocrotonic acid ester was methyl, ethyl, -propyl, isopropyl, or -butyl, -hexyl, p-cyanoethyl, p-hydroxyethyl, carbethoxymethyl, benzyl, phenyl, o-tolyl, dimethylaminopropyl, y-hydroxypropyl etc ... 

In 5 ml of isopropyl alcohol were dissolved 1.5 g (0.01 mole) of 3-nitrobenzaldehyde, 2.6 g (0.01 mole) of l-benzyl-3-acetoacetyloxypyrrolidine, and 1.3 g (0.01 mole) of p-aminocrotonic acid methyl ester and then the solution was refluxed for 8 hours. The solvent was distilled off under reduced pressure, the residue obtained was dissolved in a small amount of chloroform, and the solution was applied to silica gel column chromatography (column diameter 1.5 cm, height 20 cm, and about 200 ml of chloroform was used as the eluent). The eluates were collected and concentrated to give 3.4 g of oily... 

Acetoacetic acid N-benzyl-N-methylaminoethyl ester p-Aminocrotonic acid methyl ester m-Nitrobenzaldehyde... 

A mixture of 4.98 g of acetoacetic acid N-benzyl-N-methylaminoethyl ester, 2.3 g of p-aminocrotonic acid methyl ester, and 3 g of m-nitrobenzaldehyde was stirred for 6 hours at 100°C in an oil bath. The reaction mixture was subjected to a silica gel column chromatography (diameter 4 cm and height 25 cm) and then eluted with a 20 1 mixture of chloroform and acetone. The effluent containing the subject product was concentrated and checked by thin layer chromatography. The powdery product thus obtained was dissolved in acetone and after adjusting the solution with an ethanol solution saturated with hydrogen chloride to pH 1-2, the solution was concentrated to provide 2 g of 2,6-dimethyl-4-(3 -nitrophenyl)l,4-dihydropyridine-3,5-dicarboxylic acid 3-methylester-5-p-(N-benzyl-N-methylamino)ethyl ester hydrochloride. The product thus obtained was then crystallized from an acetone mixture, melting point 136°C to 140°C (decomposed). 

Nitrobenzylideneacetoacetic acid methyl ester p-Aminocrotonic acid isopropyl ester... 

The efficiency of p-aminocrotonic acid esters as stabilizers is increased by the addition of lubricants such as soya oil (2 or 3 parts by weight). 

Displacement of activated chlorine atoms also proceeds with certain types of organic compounds, but only in the presence of Lewis acid catalysts. Particular examples include epoxides, polyhydric alcohols, trialkylphosphites (12), and P-aminocrotonates (13). These additives are commonly used in conjunction with metallic stabilizers to provide complete, high performance, commercial stabilizer packages. 

With the exception of diaryl ketones, all aldehydes and ketones undergo the 4CC as the carbonyl component (4). Note that the derivatives of the a-oxocarboxylic acids react very well as the carbonyl components (4),2944 whereas the derivatives of the P-oxocarboxylic acids may form the resonance-stabilized derivatives of P-aminoacrylic acid, such as ethyl P-aminocrotonate (45), which can even be used as the amine component (43) of the Ugi reaction.45... 

Gdrlitzer and Vogt employed the Hantzsch 1,4-dihydropyridine synthesis in their preparation of novel thiopyrone derivatives for use as potential leukotriene antagonists for the treatment of asthma.Reaction of aldehydes 224 and 226 with P-aminocrotonate 214 in glacial acetic acid at 50-60 °C for a period of 24 h gave the corresponding dihydropyridine derivatives 225 and 227 in 83 and 86% yield, respectively. 

Sagitullina and co-workers synthesized a number of nitropyridines and their quaternary salts using a two-component Hantzsch 1,4-dihydropyridine synthesis. Treatment of 2-nitro-l,3-diphenylpropenone 258 with p-aminocrotonate derivatives 259, 210, 217 and 263 in acetic acid at room temperature gave the corresponding 1,4-dihydropyridine derivatives in modest yields. The corresponding salts (not shown) were produced using dimethylsulfate and methyl fluorosulfonate. 

Vigante and co-workers used the Hantzsch synthesis to prepare a series of novel symmetrical and unsymmetrical 1,4-dihydropyridine analogs to evaluate their antioxidant ability and therapeutic potential for the treatment of cancer. Reaction of P-unsaturated ketone 278 with p-aminocrotonate derivatives 214 and 210 in refluxing acetic acid gave the corresponding 1,4-dihydropyridine derivatives 279 and 280 in 70% and 65% yield, respectively. This method proved more effective than traditional Hantzsch syntheses involving phenothiazine and either 2 equiv methyl acetoacetate (37%) or P-... 

Of the amines, esters of /3-aminocrotonic and p-aminobenzoic acids, p-aminobenzenesulfamide [63, 266], hexamethylenetetramine [267], and certain others have been used for the stabilization of polyvinyl chloride. Phenyl-/ -naphthylamine, ethylphenylethanolamine [269], dicyanallqtl-amines [270], caprolactam [271], and N-(p-aminophenyl)hexamethylene-imine [268] have been recommended in the patent literature for the stabilization of polyvinyl chloride and vinyl chloride copolymers,... 

Carter, H. E., P. Handler, and D. B. Melville Azlactones I. Preparation of Benzoyl-a-aminocrotonic Acid Azlactone and the Conversion of Allo-Threonine to Threonine. J. Biol. Chem. 129, 359 (1939). 

The variety of substances used as additives in polymers is considerable. For example, the fillers may include china clay, various forms of calcium carbonate, talc, silicas (diatomaceous silica), silicates, carbon black, etc. The impact modifiers typically include other polymers. Plasticizers include certain polymers with low (oligomers), dialkyl phthalates, dialkyl sebacates, chlorinated paraffin waxes, liquid paraffinic fractions, oil extracts, etc. Heat stabilizers include heavy metals salts such as basic lead carbonate, basic lead sulfate, dibasic lead phosphite (also acting as a light stabilizer), dibasic lead phthalate, stearates, ricinoleates, palmitates and octanoates of cadmium and barium, epoxide resins and oils, amines, diphenylurea, 2-phenylindole, aminocrotonates. The antioxidants include tris-nonyl phenyl phosphite, 2,6-di-ferf-butyl-p-cresol (BHT), octadecyl-3,5-di-terf-butyl-4-hydroxyhydrocinnamate, etc. The UV stabilizers include modified benzophenones and benzotriazoles. Processing lubricants include calcium stearate, stearic acid, lead stearate, various wax derivatives, glyceryl esters and long-chain acids. Fire retardants include antimony oxide, some pyrophosphates, etc. 

To a hot solution of 3.12 g 5-chloro-2-methyl-l,4-p-benzoquinone (19.9 mmol) in 15 mL acetic acid, was added 3.14 g r-butyl-3-aminocrotonate (20 mmol). After 30 min without the application of heat, the solution was cooled, and the resulting pink precipitate was filtered and washed with chilled acetic acid to give 2.99 g r-butyl 4-chloro-5-hydroxy-2,7-dimethylindole-3-carboxylate, in a yield of 51%, m.p. 178-180°C (dec.)... 

The synthesis of the thiazole nucleus from aminothiocyanogen and ketones (these Reports, Vol. 2, p. 589) is also applicable to enamines derived from jS-dicarbonyl compounds. Thus, 3 aminocrotonic ester (10) or 2-aminopent-2-en-4-one (11) yield the intermediate enamines (12), which are cyclized to 2-aminothiazoles (13) under the influence of alkalis, and to A -thiazol-2-ones (14) by acids. ... 

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