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N- a-amino

Carbohydrate-derived titanium cnolates also provide yvn-x-amino-/l-hydroxy esters of high diastcrcomeric and enantiomeric purity. For this purpose, the lithium enolate derived from ethyl (2,2,5,5-tetramcthyl-2,5-disilapyrrolidin-l-yl)acetate is first transmctalated with chloro(cy-clopentadienyl)bis(1,2 5,6-di-0-isopropylidene-a-D-glucofuranos-3-0-yl)titanium and subsequently reacted with aldehydes.. vj-n-a-Amino-/ -hydroxy esters are almost exclusively obtained via a predominant /te-side attack (synjanti 92 8 to 96 4 87-98% ee for the xvn-adducts)623-b. [Pg.476]

Thioessigsaure wirkt auf Benzoesaure-amid-hydroximid uur acylierend unter Bildung von 0-Acetvl-N-(a-amino-benzyliden)-hydroxylaminno. Aus 4-(Amino-hydroximino-methyl)-5-oxo-2,2,3-trimethyl-2,5-dihydro-furan entsteht in siedender Essigsaure das N-Acetyl-Derivat I82, das unter diesen Bedingungen nicht zum 1,2,4-Oxadiazol cyclisiert. [Pg.420]

Die Umsetzung von Benzoesaure-amid-hydroximid mit Keten in benzolischer Losung bei 0° licfert nur das primare Additionsprodukt 0-Acety]-N-(a-amino-benzyliden)-hydroxylamin in 82% Ausbeute116. [Pg.426]

D-Glucose h-lysine. HCl (millimoles) pH Total N a-Amino Na Color... [Pg.84]

N-a-Amino acids (10 mg) were typically dissolved in 200 mM, pH 10 sodium metaborate buffer (1 ml), and methylated directly by the addition of a 1 1 v/v solution (20 gl) of [ C]iodomethane in acetonitrile, with rapid mixing of the sealed biphasic mixture at 37°C for 24 h. Cystine dimethyl ester, in particular, was first converted to the diamide at pH 9.5 using ammonia. Histidine amide was first acetylated prior to reaction with iodomethane. [Pg.220]

Since the process represented by reactions (4a) and (4b) is a simple addition polymerization it leads to a distribution of molecular weights of the Poisson type [2]. At any st e of the reaction the concentration of polymer molecules containing n a-amino acid units [P ] is given by... [Pg.587]

If N a-amino acids are converted into the corresponding peptides, at least 3N -1 steps of preparative procedures must occur in order to protect, connect and deprotect the functional groups of the a-amino acids. [Pg.141]

The influence of a large number of oc-amino acids on the values of and k at have been determined. These a-amino acids included glycine, L-valine, L-leucine, L-phenylalanine, L-tyrosine, L-tryptophan, NOrmethyl-L-tryptophan (L-abrine), N-methyl-L-tyrosine, N,N-dimethyl-L-tyrosine and p -me thoxy-N-me thyl -L -phenyl al anine. [Pg.175]

The most suitable synthetic method for these products is the heterocyc-lization reaction of N-thioacyl derivatives of amino acids (202) with phosphorus tribromide (378, 442-450, 559, 560) or anhydrous trifluoroacetic acid (448, 449, 451, 452) (Scheme 103). Treatment of N-thioacyl amino acids with acetic anhydride leads directly to the thiazolylacetate without isolation of an intermediate thiazolinone (365. 452). 2-Alkoxy-derivatives of A-2-thiazoline-5-one, however, can be obtained without acetylation by this method (453, 454). [Pg.426]

TABLE n-36. 2,5-DIAMINOTHIAZOLE DERfVATIVES FROM a-AMINO-NITRILES AND ISOTHIOCYANaTES. [Pg.290]

Edman degradation (Section 27 13) Method for determining the N terminal amino acid of a peptide or protein It in volves treating the material with phenyl isothiocyanate (CgH5N=C=S) cleaving with acid and then identifying the phenylthiohydantoin (PTH derivative) produced Elastomer (Section 10 11) A synthetic polymer that possesses elasticity... [Pg.1282]

P-Endorphin. A peptide corresponding to the 31 C-terminal amino acids of P-LPH was first discovered in camel pituitary tissue (10). This substance is P-endorphin, which exerts a potent analgesic effect by binding to cell surface receptors in the central nervous system. The sequence of P-endorphin is well conserved across species for the first 25 N-terminal amino acids. Opiates derived from plant sources, eg, heroin, morphine, opium, etc, exert their actions by interacting with the P-endorphin receptor. On a molar basis, this peptide has approximately five times the potency of morphine. Both P-endorphin and ACTH ate cosecreted from the pituitary gland. Whereas the physiologic importance of P-endorphin release into the systemic circulation is not certain, this molecule clearly has been shown to be an important neurotransmitter within the central nervous system. Endorphin has been invaluable as a research tool, but has not been clinically useful due to the avadabihty of plant-derived opiates. [Pg.175]

Rearrangement of N.N-dimethyttiydrazone or tosylate derivatives of oxime to azirines and from there to a-amino ketones. [Pg.271]

The Tcrom ester is prepared from the cesium salt of an N-protected amino acid by reaction with 2-(trifluoromethyl)-6-chromylmethyl bromide (DMF, 25°, 4 h, 53-89% yield). Cleavage of the Tcrom group is effected by brief treatment with n-propylamine (2 min, 25°, 96% yield). It is stable to HCl/dioxane, used to cleave a BOC group. ... [Pg.257]

The bulky triphenylmethyl group has been used to protect a variety of amines such as amino acids, penicillins, and cephalosporins. Esters of N-trityl a-amino acids are shielded from hydrolysis and require forcing conditions for cleavage. The a-proton s also shielded from deprotonation, which means that esters elsewhere in the molecule can be selectively deprotonated. [Pg.366]

Acetyl-a-amino-n-butyric acid [34271-24-4] M 145.2, pK 3.72. Crystd twice from water (charcoal) and air dried [King and King J Am Chem Soc 78 1089 7956]. [Pg.88]

One of the historically most significant examples of aromatie nueleophilie substitution is the reaetion of amines with 2,4-dinitrofluorobenzene. This reaetion was used by Sanger to develop a method for identifieation of the N-terminal amino acid in proteins and the proeess opened the way for struetural eharacterization of proteins and other biopolymers. [Pg.592]


See other pages where N- a-amino is mentioned: [Pg.476]    [Pg.198]    [Pg.25]    [Pg.285]    [Pg.921]    [Pg.245]    [Pg.476]    [Pg.198]    [Pg.25]    [Pg.285]    [Pg.921]    [Pg.245]    [Pg.57]    [Pg.193]    [Pg.432]    [Pg.435]    [Pg.440]    [Pg.235]    [Pg.331]    [Pg.167]    [Pg.197]    [Pg.662]    [Pg.175]    [Pg.448]    [Pg.451]    [Pg.119]    [Pg.329]    [Pg.316]    [Pg.315]    [Pg.316]    [Pg.511]   
See also in sourсe #XX -- [ Pg.676 ]




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A-Amino acid N-carboxyanhydrides

A-Amino-n caproic acid

A-Amino-n-butyric acid

A-amino-n-butanoic acid

N a-amino acids

N- amino

N-Acetyl a-amino acids

N-Carboxy a-amino acid anhydrides NCAs)

N-carboxy-a-amino acid anhydride

Optically active N-protected a-amino

Optically active N-protected a-amino aldehydes

Polymerization of N-carboxy-a-amino acid anhydrides

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