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Pyrazolines, 3-amino

A mechanism has been proposed to rationalize the results shown in Figure 23. The relative proportion of the A -pyrazolines obtained by the reduction of pyrazolium salts depends on steric and electronic effects. When all the substituents are alkyl groups, the hydride ion attacks the less hindered carbon atom for example when = Bu only C-5 is attacked. The smaller deuterohydride ion is less sensitive to steric effects and consequently the reaction is less selective (73BSF288). Phenyl substituents, both on the nitrogen atom and on the carbon atoms, direct the hydride attack selectively to one carbon atom and the isolated A -pyrazoline has the C—C double bond conjugated with the phenyl (328 R or R = Ph). Open-chain compounds are always formed during the reduction of pyrazolium salts, becoming predominant in the reduction of amino substituted pyrazoliums. [Pg.243]

Tautomerism has been discussed in Section 4.04.1.5.2. It concerns prototropic tautomerism and the decreasing order of stability is (hydrazone) >A (azo)> A (enehydrazine). The isomerization A -> A occurs via a A -pyrazoline (65BSF769). Pyrazolidones and amino-A -pyrazolines exist as such. The only example of non-prototropic tautomerism deals with the isomerization (403) —> (404) (74CJC3474). This intramolecular process is another example (Section 4.04.1.5) of the thermodynamic analogy between prototropy and metallotropy. [Pg.254]

Pyrazolines substituted at position 4 or 5 with hydroxy or amino groups readily eliminate a molecule of water or amine yielding pyrazoles. The 4-substituted derivatives are relatively more stable than the 5-substituted ones, because for the last group the lone pair at N-1 assists the elimination (407) -> (408) -> (409). The sulfonyl group at position 1 is also easily eliminated and this property is taken advantage of in Dorn s elegant synthesis of 3-aminopyrazole (Section 4.04.3.3.1). [Pg.254]

Methyl-l-phenyl-3-pyrazolin-5-one gives a green-black dye (736) with 4-nitroso- or 4-amino-dimethylaniline and silver chlorides in the presence of light, a process of great importance in colour photography (B-76MI40403). [Pg.299]

Pyrazolin-5-one, 3-amino-1 -phenyl- C NMR, 5, 194 (70JCS(C)1842) 2-Pyrazolin-5-one, 4,4-diethyl-3-methoxy- C NMR, 5, 194 (80CB3910)... [Pg.48]

Pyrazblin-5-one, 3-alkyl-(l,2,4-thiadiazol-5-yl)-reactions, 6, 483 2-Pyrazolin-5-one, 3-amino-tautomerism, 5, 215 2-Pyrazolin-5-one, 4,4-diazido-rearrangement, 5, 720 2-Pyrazolin-5-one, 3-hydroxy-tautomerism, 5, 215 2-Pyrazolin-5-one, 3-methyl-1 -phenyl-reactions, 5, 252... [Pg.776]

Amino-2,3-dimethyl-l-phenyl-3-pyrazolin-5-one Potassium hexacyanoferrate(III) Ammonia solution (25%) Ethanol... [Pg.152]

Pyran, tetrahydro-, 3 chloro 2 methyl [2H Pyran, tetrahydro, 3 chloro-2-mcthyl ], cis, trans mixture, 55, 64 2-PYRAZOLIN-5-ONES, 3-alkyl-, 55, 73 2-Pyrazolin 5-one, 3-(l-propyl)-, 55, 73 Pyridine, 2-amino-, p-bromination of, 55, 23... [Pg.143]

Amino-2, 5-dichlorobenzophenone (ADB) 226,227 4-Amino-2,3-dimethyl-l-phenyl-3-pyrazolin-5-one 158 2-Aminodiphenyl reagent 157,158 Aminoglycoside antibiotics 107, 270, 284, 354, 380, 423, 434... [Pg.232]

Ketene dithioacetal 130 reacts with 3-amino-2-pyrazolin-5-one 129 to give the highly functionalized pyrazolopyridine 131, which is converted into the bispyrazolopyridine 132 by reaction with hydrazine hydrate (Scheme 9) <1997JCM256>. [Pg.728]

B. 3-Amino-3-pyrazoline sulfate. In a 2-1. four-necked flask equipped with a reflux condenser, a dropping funnel, a thermometer, and a mechanical stirrer with four blades (Note 1) is placed 308 g. (169 ml., 3.0 moles) of 95% sulfuric acid (sp. gr. 1.834). Absolute ethanol (450 ml.) is added dropwise over 20-30 minutes. The internal temperature is maintained at 35° by cooling. A solution of 85.1 g. (1.00 mole) of j3-cyanoethylhydra-... [Pg.5]

Arenes, polyalkyl, oxidation with per-oxytrifluoroacetic acid and boron trifluoride, 48, 89, 90 Arenesulfonyl chlorides, reaction with 3-amino-3-pyrazoline, 48, 11 Aromatic aldehydes. Mesitalde-HYDE, 47, 1... [Pg.69]

Imidazole, purification of, 48, 45 reaction with phosgene, 48, 44 Imldazole, 1,1 -carbonyldi-, 48, 44 Imidazolium chloride, 48, 46 3-Imino-l-( -tolylsulfonyl)pyrazolidine, from 3-amino-3-pyrazoline sulfate and / -toluenesulfonyl chloride, 48, 9... [Pg.76]

Elimination, of arenesulfinate ion from 1 -alkyl-2-arylsulfonyl-5-amino-4-pyrazoline salts, 48,12 of carbon dioxide and iodobenzene from diphenyliodonium-2-car-boxylate to generate benzyne, 46,107... [Pg.71]

The spiropyrazohnes obtained from 51 were converted into enantiopure A -pyrazoline-3-carboxylates and 1 -(hydroxyethyl)cyclopropane-1 -carboxylates (128). Those obtained from 54 and 55 were transformed into optically active a-spirocyclopropyllactones and 3-amino-3-(hydroxyethyl)pyrrolidin-2-ones (130). The spiropyrazoline obtained from a chiral propylidene-diketopiperazine and diazomethane was converted into (+)-(lR,25)-l-amino-2-ethyl)cyclopropane-l-carboxylic acid (allocoronamic acid) (135). [Pg.554]

Cyclocondensation of 3-amino-2-pyrazolin-5-ones (22) with )S-diketones affords either pyrazolo[3,4-d]pyridines 23 or pyrazolo[l,5-a]pyrimidines 24. In acid 24 is produced, whereas under alkaline conditions 23 is the major product (60CB1106 62LA104). [Pg.323]

The reaction of 3-amino-2-pyrazolin-5-one with diketene afforded 2-hy-droxy-7-methyl-1,2-dihydropyrazolo[ 1,5-a]pyrimidine-5-one (49US2481466) (Scheme 1). [Pg.333]


See other pages where Pyrazolines, 3-amino is mentioned: [Pg.775]    [Pg.775]    [Pg.775]    [Pg.775]    [Pg.297]    [Pg.775]    [Pg.775]    [Pg.775]    [Pg.775]    [Pg.215]    [Pg.281]    [Pg.775]    [Pg.17]    [Pg.86]    [Pg.17]    [Pg.17]    [Pg.100]    [Pg.727]    [Pg.167]    [Pg.81]    [Pg.82]    [Pg.631]    [Pg.631]    [Pg.24]    [Pg.553]    [Pg.162]    [Pg.233]    [Pg.338]    [Pg.741]   
See also in sourсe #XX -- [ Pg.20 , Pg.247 ]




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2-pyrazoline

3- Amino-2-pyrazolin-5-ones, 136,

3- Amino-3-pyrazoline, reaction with

4- Amino-2-pyrazolin-5-ones synthesis

4-Amino-3-pyrazolin-5-ones acylation

4-Amino-3-pyrazolin-5-ones alkylation

4-Amino-3-pyrazolin-5-ones reaction with aldehydes

Arenesulfonyl chlorides, reaction with 3-amino-3-pyrazoline

Pyrazolinate

Pyrazolines

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