A-hydroxy succinimide

Further versatihty was added to the range of substituents available for introduction into the 6a-position by use of the 6a(succinimido-oxy) derivative (18) prepared by treatment of the 6a-(methylthio) derivative (17) with A/-hydroxy-succinimide and silver(I) acetate in dimethylformamide in virtually quantitative yield. In this way the 6a-cyanopeniciILin (19, X = CN), 6a-viny1penici11in (19, X = CH=CH2) and 6a-pheny1penici11in (19, X = C H ) could be prepared in high yield (43). 

The Bsmoc derivative is formed from the chloroformate or the A -hydroxy-succinimide ester. It is cleaved rapidly by a Michael addition with tris(2-aminoethyl)amine at a rate that leaves Fmoc derivatives intact. More hindered bases, such as A -methylcyclohexylamine or diisopropylamine, do not react with the Bsmoc group, but do cleave the Fmoc group, illustrating the importance of steric effects in additions to Michael acceptors. 

The most widely applied principle is haptenylation of amino groups via A-hydroxy succinimide esters (NHS-ES). For convenient protein-labeling procedures,... 

The Step 2 product (0.2 mmol) was dissolved in 10 ml of CH2CI2 and treated with A-hydroxy-succinimide (0.41 mmol) and dicyclohexylcarbodiimide (0.42 mmol). The mixture was stirred overnight at ambient temperature and then filtered and concentrated. The residue was precipitated in 2-propanol/diethyl ether, 1 1, and filtered to yield 1.6 g of isolated product. 

Although of more academic than commercial importance, aspartase can also be chemically activated by acetylation using acetic anhydride or A-hydroxy-succinimide [42], Acetylated enzyme exhibits a twofold activation at pH 7.0, but at pH... 

Antibody-masking enzyme tag immunoassay Adenosine 5 -monophosphate S-Acetylmercaptosuccinic anhydride Alkaline phosphatase anti-alkaline phosphatase (enzyme-antibody) complex Alkaline phosphatase 5-Aminosalicylic acid Adenosine 5 -triphosphate Aa-Benzoyl-L-arginine ethyl ester (-f-)-Biotin bromoacetyl hydrazide (-b)-Biotin Y-aminocaproic acid A-hydroxy-succinimide ester Bis-diazotized benzidine -Galactosidase (-I- )-Biotin hydrazide (-I- )-Biotin-A-hydroxysuccinimide ester (-I-)-Biotin p-nitrophenyl ester Bridged avidin-biotin (method)... 

SPDP 3-(2-Pyridyldithio)propionic acid A-hydroxy-succinimide ester... 

Reaction with a complex A-hydroxy-succinimide ester derivative of glass 3.4.23.1 Carbodi-imide-assisted reaction with... 

A great deal of work has been done on the in situ activation of carboxylic acids toward nucleophilic substitution by amines. This type of reaction forms the backbone of the methods for synthesis of peptides and proteins. Among the methods for carboxylate activation which have achieved importance in peptide synthesis that were mentioned in Section 3.4.1 are the carbodiimide and isoxazolium methods. Since amines are better nucleophiles than alcohols, the leaving group in a potential acylation reagent need not be as reactive as is necessary for alcohols. The p-nitrophenyl and 2,4,5-trichlorophenyl esters of amino acids are sufficiently reactive toward amines to be useful in peptide synthesis. Acyl derivatives of hydroxysuccinimide are also useful for synthesis of peptides and other types of amides.Like the p-nitrophenyl esters, the acylated A-hydroxysuccinimides can be isolated and purified, but rapidly react with free amino groups. The A-hydroxy-succinimide that is liberated is easily removed because of its solubility in dilute... 

It should be noted that fluorescent chitosan can be prepared inrather simple ways. A typical synthesis of fluorescent chitosan is the following chitosan (0.20 g) was dissolved in a mixture of 15 mL of DMF and 20 mL of 1.4% acetic acid aqueous solution. Then A-hydroxy succinimide ester (37.10 mg) dissolved in 5 mL of dimethylformamide was dropwise added into said solution and the reaction was carried out at 50 °C for 24 h under nitrogen with stirring, then 3 M NaOH was added the precipitate was filtered, redissolved in 1.4% acetic acid, and reprecipitated. The resultant light yellow fluorescent chitosan, washed with tetrahydrofuran until no unreacted ester was detected by UV in the filtrate, was dried under vacuum the yield was 95% (Yang et al., 2008). 

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