The Synthesis of Some Amines and Amino Acids Containing the Pyrazole Nucleus

Jones, Reuben G.

doi:10.1021/ja01180a035

Cited by 83 publications

(31 citation statements)

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“…Also in this case it was shown, in contradiction to the literature (6), that no excess of acetamidomalonate was necessary. After hydrolysis, the pure product I1 was easily isolated as crystalline monohydrochloride.…”

Section: Introductioncontrasting

confidence: 93%

“…The reaction mixture &as then stirred for 30 min at Oo C and then allowed to stand for 24 hours ait ordinary temperature; during this time the alkaline reaction disappeared. Ethanol was evaporated in vacuo, the remainder dissolved in glacial acetic acid (4 ml), concentrated hydrochloric acid added (6 ml) and the whole was gently refluxed for 6 hours. The solution was again evaporated to dryness in vacuo and the evaporation repeated twice more after dissolving in a small volume of water.…”

Section: Dl-3-(1'-pyra~olyl)-alanine-2-~~c ( I )mentioning

confidence: 99%

See 1 more Smart Citation

Synthesis of 14C‐labelled heterocyclic analogues of phenylalanine with pyrazole and furan rings

Tolman¹,

Hanuš²,

Vereš³

1968

J. Labelled Cpd. Radiopharm.

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Diethyl acetamidomalonate‐2‐14C was alkylated by l‐chloromethylpyrazole and the reaction intermediate hydrolyzed to give DL‐3‐(1′‐pyrazolyl)‐alanine‐2‐14C. By the same method, but using 3‐chloromethylpyrazole instead of the 1‐isomer, DL‐3‐(3′‐pyrazolyl)‐alanine‐2‐14C was prepared. Condensation of furfural with hydantoin‐5‐14C gave 5‐(2′‐furylidene)‐hydantoin‐5‐14C, which was subsequently reduced to 5‐(2′‐furyl)‐hydantoin‐5‐14C and this compound was hydrolyzed to DL‐3‐(2′‐furyl)‐alanine‐2‐14C. Methods for isolation and purification of the final products on microscale are described.

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Section: Introductioncontrasting

confidence: 93%

Section: Dl-3-(1'-pyra~olyl)-alanine-2-~~c ( I )mentioning

confidence: 99%

Synthesis of 14C‐labelled heterocyclic analogues of phenylalanine with pyrazole and furan rings

Tolman¹,

Hanuš²,

Vereš³

1968

J. Labelled Cpd. Radiopharm.

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“…[36,37] Our synthetic route starts from the 3-(chloromethyl)pyrazole hydrochlorides 6 a and b (obtained in two steps from the corresponding esters [38] ). For the selective attachment of the polydentate amine side arm by nucleophilic substitution, a NH protecting group had to be introduced at the pyrazole nucleus first.…”

Section: Resultsmentioning

confidence: 99%

Cooperative Transformations of Small Molecules at a Dinuclear Nickel(II) Site

et al. 1999

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Using the possibility of tuning the metal ± metal distance in pyrazolatebased bimetallic complexes by the length of the chelating side arms attached to the heterocycle, we have synthesized related dinickel(ii) complexes in which either a hydroxide (1) or a H 3 O 2 unit (2) spans the two metal centers within the bimetallic pocket. Complex 1 exhibits strong antiferromagnetic coupling mediated by the bridging hydroxide unit (J À 56.9 cm À1 ), while 2 shows Curie ± Weiss behavior over a wide temperature range. The H 3 O 2 unit in 2 acts like the resting form of an active metalbound hydroxide and allows the study of cooperative transformations of small molecules at a dinickel(ii) site relevant to the active site of the metalloenzyme urease. Firstly, it mediates the hydration of various nitriles to give the respective m-amidato-N,O-bridged complexes 3 a ± c. Reaction of 2 with urea affords complex 5 with an N,O-bridging deprotonated urea, which when heated releases ammonia to yield the cyanato-bridged dinickel(ii) compound 4. This product is also obtained when 2 is treated with dimethylcyanamide. Unactivated amides dimethylformamide (DMF) and dimethylamide (DMA) are hydrolyzed by 2 only sluggishly, while the stoichiometric hydrolysis of esters such as ethyl acetate and ethyl propionate runs more cleanly to afford the carboxylato-bridged bimetallic complexes 10 b and c. Likewise, hydrolytic cleavage occurs with g-butyrolactone to give complex 10 d. We propose that these reactions proceed by cooperative action of the two metal ions within the bimetallic pocket of the dinickel(ii) core. Possible alternatives are addressed by investigation of analogous mononuclear nickel(ii) complexes 8 a and b in conjunction with a corresponding dimeric compound 9 and by the reaction of 2 with an excess of acetate to yield the dinickel(ii) complex 11, in which a formerly chelating side arm has been driven out of the coordination sphere. Complexes 1´(BPh 4 ) 2 , 2( BPh 4 ) 2 , 3c´(ClO 4 ) 2 , 4´(BPh 4 ) 2 , 8 b( ClO 4 ) 2 , 9´(ClO 4 ) 2 , 10 d´(ClO 4 ) 2 , and 11´(ClO 4 ) have been characterized structurally by X-ray crystallography.

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“…2-Chloromethylimidazole (VII) was synthesized by reducing the corresponding aldehyde to the alcohol followed by treatment with SOCI> Ethyl-4-pyrazolecarboxylate was synthesized by refluxing 4-pyrazolecarboxylic acid in a solution of ethanol and dry HC1 (reaction 1), followed by crystallization of the product after removal of the solvent. The resulting ester was converted to 4-hydroxymethylpyrazole by refluxing with LialH4 in dry Et20 (reaction 2) followed by soxlet extraction (Jones, 1949). This product was then converted to 4-chloromethylpyrazole (I) as described above (reaction 3).…”

Section: Methodsmentioning

confidence: 99%

Conversion of cysteinyl residues to unnatural amino acid analogs. Examination in a model system

Schindler¹,

Viola²

1996

J Protein Chem

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Improved and efficient techniques have led to an explosive growth in the application of site-directed mutagenesis to the study of enzymes. However, the limited availability of only those 20 amino acids that are translated by the genetic code has prevented the systematic variation of an amino acid's properties in order to define more precisely its role in the catalytic mechanism of an enzyme. An approach is being examined that combines the high specificity of site-directed mutagenesis with the flexibility of chemical modification to overcome these limitations. A set of reagents has been synthesized and reacted with a cysteine model to produce a series of amino acid structural analogs at appreciable rates and in good overall yields. The selective incorporation of these analogs in place of important functional amino acids in a protein will allow a more detailed examination of the role of that amino acid.

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The Synthesis of Some Amines and Amino Acids Containing the Pyrazole Nucleus

Cited by 83 publications

References 0 publications

Synthesis of 14C‐labelled heterocyclic analogues of phenylalanine with pyrazole and furan rings

Synthesis of 14C‐labelled heterocyclic analogues of phenylalanine with pyrazole and furan rings

Cooperative Transformations of Small Molecules at a Dinuclear Nickel(II) Site

Conversion of cysteinyl residues to unnatural amino acid analogs. Examination in a model system

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