Carbonyl diimidazole activation

In most cases, the proteia is immobilized onto y-aminopropyl sUica and covalently attached usiag a cross-linking reagent such as -carbonyl diimidazole. The tertiary stmcture or three dimensional organization of proteias are thought to be important for their activity and chiral recognition. Therefore, mobile phase conditions that cause proteia "deaaturatioa" or loss of tertiary stmcture must be avoided. 

A one-pot synthesis of 2,5-disubstituted 1,3,4-oxadiazoles from acids and acyl hydrazides has recently been reported. The method involves an activation of an acid with carbonyl diimidazole followed by the addition of benzoyl hydrazide and then the addition of CBr4 and Ph3P. Under the conditions, the dehydration proceeds smoothly to provide the desired oxadiazoles in high yields <2006TL4827>. 

Reaction of the imidazole (7-4) with the benzofuran derivative (6-7) leads to the displacement of the benzylic halogen and the formation of the alkylation product (8-1). Treatment of that intermediate with trifluoroacetic acid breaks open the urethane to afford the corresponding free amine. This is allowed to react with ttiflic anhydride to afford the trifluoromethyl sulfonamide (8-2). The ester group on the imdidazole is then saponified, and the newly formed acid is reacted with carbonyl diimidazole. Reaction with ammonia converts the activated carboxyl group to the amide. There is thus obtained the angiotensin antagonist saprisartan (8-3) [6]. 

Matsuda, Akutsu, et al. [141] carried out chemical fixation of GRGDSP onto a poly(vinyl alcohol) film which had been activated by carbonyl diimidazol in dimethylformamide. For comparison, fibronectin was also immobilized on a poly(vinyl alcohol) film by the same technique. Matsuda et al. found that bovine endothelial cells (ECs) adhered well to the peptide- and fibronectin-immobilized film furthermore, after a three-day incubation, aggregated ECs floated on nontreated PVA film, while the peptide-immobilized surface greatly enhanced cell spreading and growth, which surpassed that on fibronectin-bound PVA. 

Immunoaffinity chromatography cleanup has also been applied as an ideal and reliable strategy for residue analysis. Immunoaffinity columns prepared by coupling the antibodies to a cyanogen bromide-activated support were used to analyze avermectin BI residues in cattle tissues (359) and ivermectin in sheep serum (376). An immunoaffinity column prepared by an alternative activation/ coupling procedure with carbonyl diimidazole was also employed to analyze ivermectin residues in swine liver (361) since the earlier-reported methods did not work well in the analysis of this matrix. This recent work demonstrated the high specificity of tire antibody-mediated cleanup, but also showed that the immunoaffinity procedures could not always or completely eliminate matrix interference of samples. Therefore, application of additional cleanup steps before or after these procedures is often inevitable. 

Carbon monoxide oxidase 893 Carbonic acid, pkCa value of 99 Carbonic anhydrase 443,676 - 678,710 active site structure 679 mechanism 678 turnover number of 458,678 Carbonium ion. See Carbocation 1,1 -Carbonyl-diimidazole 105s Carbonyl group... 

Amines can be linked to polymeric alcohols as carbamates. Carbamate attachment of amines can be achieved by reaction of isocyanates with alcohol linkers, or by treatment of alcohol linkers with phosgene [339,427,428] or a synthetic equivalent thereof, followed by exposure to the amine (Figure 3.26). The reagents most commonly used for the activation of alcohol linkers are 4-nitrophenyl chloroformate [69,429-436] and carbonyl diimidazole [427,437-440], The preparation of support-bound carbamates is discussed in Section 14.6. 

As alternatives to 4-nitrophenyl chloroformate, carbonyl diimidazole [100-102] or di-A-succinimidyl carbonate [103,104] can be used to convert polymeric alcohols into alkoxycarbonylating reagents suitable for the preparation of support-bound carbamates. Polystyrene-bound alkoxycarbonyl imidazole is less reactive than the corresponding 4-nitrophenyl carbonate, and sometimes requires heating to undergo reaction with amines. Additional activation of these imidazolides can be achieved by N-methylation (Entry 9, Table 14.7). 

MfV -carbonyl diimidazole (CDI). We wanted to use the same solvent for the activation as for the reduction as this would allow simple processing and efficient solvent recovery. Eventually we selected CDI on the basis that the very high chemical yield using that reagent, 96% yield over three chemical reactions, outweighed the small additional reagent cost. CDI costs around 8/mol. The amine 6 and the imidazolide are both highly soluble in ethyl acetate as is the main by-product imidazole. In contrast, the desired amide 10 had very low solubility. This led to a very simple process where the streams are mixed, reacted, and the product collected by filtration. There are no aqueous workups involved. Subsequently, a name has been coined for this type of efficient process—direct-drop or direct-isolation process. The preparation of compound 9 is another example of a direct-drop process. 

Ozonolysis of the alkene of C frees the carboxylic acid of D which reacts with carbonyl diimidazole E (CDl) in a nucleophilic substitution at the carbonyl group, with the relatively stable imidazole anion as the leaving group. The product is an activated ester , like an anhydride, from which the anion of nitromethane displaces the second molecule of imidazole to give the product F. 

McConway MG, Chapman RS. Application of solid-phase antibodies to radioimmunoassay evaluation of two polymeric microparticles, dynospheres and nylon, activated by carbonyl-diimidazole or tresyl chloride. J. Immunol. Methods 1986 95 259-266. 

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