N-hydroxysuccinimide/

With the dicyclohexylcarbodiimide (DCQ reagent racemization is more pronounced in polar solvents such as DMF than in CHjCl2, for example. An efficient method for reduction of racemization in coupling with DCC is to use additives such as N-hydroxysuccinimide or l-hydroxybenzotriazole. A possible explanation for this effect of nucleophilic additives is that they compete with the amino component for the acyl group to form active esters, which in turn reaa without racemization. There are some other condensation agents (e.g. 2-ethyl-7-hydroxybenz[d]isoxazolium and l-ethoxycarbonyl-2-ethoxy-l,2-dihydroquinoline) that have been found not to lead to significant racemization. They have, however, not been widely tested in peptide synthesis. 

Pha.rma.ceutica.ls. Neopentanoic acid derivatives are widely used in the preparation of pharmaceuticals, eg, as a means of introducing the tert-huty group into a molecule. More frequendy, however, derivatives have been prepared that exploit the enhanced hydrolytic stabiUty of the neopentanoate group. Eor example, when salmon calcitonin is treated with N-hydroxysuccinimide pivalate [42014-50-6], the resulting derivative retains the biological activity of the precursor, but gives an extended duration of activity (51). 

Treatment of N hydroxysuccinimide with trifluoroacetic anhydnde gives N trifluoroacetoxysuccinimide quantitatively [27] Some otherwise hardly accessible trifluoroacetylated tertiary alcohols are readily prepared, though in poor yields, by reacting the appropriate anhydride with an excess of an organometallic reagent [22] (equation 11)... 

Cefpiramide (64) is a third generation cephalosporin with a l-methyl-[lH)-tetra2ol-5-ylthio-methyl moiety at C-3 and an acylated -hydroxyphenylglycine moiety at C-7. It includes in its activity spectrum reasonable potency in vitro against many strains of Pseudomonas. It can be synthesized in a variety of ways including condensation of cephalosporin antibiotic 63 with 6-methyl-4-(l-H)-pyridone-3-carboxylic acid in the form of its active N-hydroxysuccinimide ester (62) to produce cefpiramide (64) [20,21],... 

Preparation of N-Hydroxysuccinimide Ester of L-(-) y-Benzyloxycarbonylamino-a-Hydroxy-butyric Acid A solution of 10.6 grams (0,042 mol) of L-(-)-7-benzyloxycarbonylamino-o-hydroxybutyric acid and 4.8 grams (0.042 mol) of N-hydroxysuccinimide in 200 ml of... 

Activated esters for use in peptide-coupling reactions were produced by photolysis of optically active chromium aminocarbenes with alcohols which are good leaving groups, such as phenol, pentafluorophenol, 2,4,5-trichlorophenol, and N-hydroxysuccinimide (Table 17) [ 109]. Since arylcarbenes bearing the op-... 

Galactosylated chitosan prepared from lactobionic acid and chitosan with l-ethyl-3-(3-dimethylaminopropyl)-carbodiimideand N-hydroxysuccinimide was a good extracellular matrix for hepatocyte attachment [155] (Fig. 4). Furthermore, graft copolymers of galactosylated chitosan with poly(ethylene glycol) or poly(vinyl pyrrolidone) were useful for hepatocyte-targeting DNA carrier [156,157]. 

Maximum residue limit Mass spectrometry Tandem mass spectrometry Material safety data sheet North American Free Trade Act N-Hydroxysuccinimide Nitrogen-phosphorus detection Neomycin phosphotransferase II Optical density Office of Plant Protection and Quarantine... 

Currently, a common form of activated mPEG used for preparation of therapeutic enzymes is mPEG-succinate-N-hydroxysuccinimide ester (SS-PEG) (11). It reacts with proteins in short periods of time under mild conditions, producing extensively modified conjugates with well preserved biological activity. However, the ester linkage between the polymer and the succinic acid residue has limited stability in aqueous media (5,12). 

Methoxypolyethylene glycol of molecular weight 5000 (Union Carbide, 60 g, 12 mmol), dried by azeotropic removal of toluene, was dissolved in toluene/dichloromethane (3 1, 200 mL) and treated with a toluene solution of phosgene (30 mL, 57 mmol) overnight. The solution was evaporated to dryness and the remainder of phosgene was removed under vacuum. The residue was redissolved in toluene/dichloromethane (2 1, 150 mL) and treated with solid N-hydroxysuccinimide (2.1 g, 18 mmol) followed by triethylamine (1.7 mL, 12 mmol). After 3 h the solution was filtered and evaporated to dryness. The residue was dissolved in warm (50 °C) ethyl acetate (600 mL), filtered from a trace of insolubles and cooled to facilitate precipitation of the polymer. The product was collected by... 

Certain esters have often been employed in attempts to confer organ selectivity to molecules possessing carboxyl functions. Thus, for example, treatment of piperidinecarboxylic acid 76 with N-hydroxysuccinimide and DCC affords the ester 77. In a convergent synthesis, the anion from diphenylacetonitrile (78) is alkylated with dibromoethane to afford the bromide 79. Alkylation of the piperidine derivative 77 with that halide 79 gives the anti-diarrheal agent difenoximide (80). The same sequence starting with the phenoxyethyl ester 81 gives fetoxylate (82). 

BMPA is N-(3-maleimidopropionic acid (or 3-maleimidopropionic acid), which contains a thiol-reactive maleimide group at one end and a carboxylate group on the other end (Rich et al., 1975 Moroder, 1983, 1987). The compound is the acid precursor to the short, heterobifunctional crosslinker 3-maleimidopropionic acid N-hydroxysuccinimide ester (BMPS). 

Amine-reactive biotinylation reagents contain reactive groups off biotin s valeric acid side chain that are able to form covalent bonds with primary amines in proteins and other molecules. Two basic types are commonly available N-hydroxysuccinimide (NHS) esters and carboxylates. NHS esters spontaneously react with amines to form amide linkages (Chapter 2, Section 1.4),... 

Dissolve 3.45mg of N-hydroxysuccinimide (NHS) in 30ml dry ethyl acetate. 

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