Hydroxamate functional groups

The acylation rate (ka) did not differ mudi between die terpolymer (PHA-MIm-AAm) and a copolymer which contains only die hydroxamate functional group (PHA-AAm, 7). In contrast, die hydrolysis of the acelyl hydroxamate intermediate was greatly accelerated by the assistance of the intrapolymeric imidazole group (60—80 fold increase in kj). 

Fig. 2. Functional groups on modified polyacrylamides (a) formed by reaction with dimethylamine and formaldehyde (Mannich reaction) (b), quatemized Mannich amine (c), carboxylate formed by acid or base-cataly2ed hydrolysis or copolymerization with sodium acrylate and (d), hydroxamate formed by...

In an attempt to prepare a catalytically active cycloamylose derivative which would retain the binding properties of an unmodified cycloamylose,7 Gruhn and Bender (1971) attached a relatively small hydroxamate function to a secondary hydroxyl group of cyclohexaamylose. The initial and most important step in the synthetic sequence is the reaction of ionized cyclo-... 

Prepare a 1M solution of hydroxylamine in coupling buffer sufficient to again treat the slide. The pH of the coupling buffer should be adjusted to pH 10 after dissolving the hydroxylamine into it. Expose the slide to the hydroxylamine solution in the same manner as the crosslinker treatment. The hydroxylamine will react with the methyl ester groups on the salicylic acids and form hydroxamate functionalities suitable for conjugation with the P(D)BA-modified protein from above. 

Enzymatic transformations of alkaloids by peroxidases most probably occur by single-step oxidations catalyzed by the HRP-I and HRP-II forms of the enzyme. The catalysis of one-electron oxidations of compounds containing aromatic hydrocarbon, hydrazine, phenol, hydroxamic acid, and amine functional groups has been recently reviewed (45, 58, 82). A brief summary of those HRP reactions that involve functional groups most commonly occurring in alkaloids is presented below. 

The ability of hydroxamic acids to act as bidentate ligands has made this functional group a key component in the design of most matrix metalloproteinase inhibitors. Due to its labile and diprotic nature, the hydroxamate is typically installed in its protected form at the end of the synthetic sequence. ... 

Thouin and Lubell have overcome some of these issues by exposing oxime resin-bound(acyl)amino acids 197-200 to a solution of anhydrous hydroxylamine in 1 6 MeOH CHCI3 (Scheme 87). Enantiopure hydroxamates, possessing a variety of functional groups, are isolated by simple evaporation of volatile solvents. 

Oximes and hydroxamic acids, together with hydroxylamines, can be generally considered as a class of compounds having a common functional group —NOH—. Additional functional features distinguish these three parent classes of compounds. Some confusion often occurs over a reagent generally called oxine . This is not an oxime (and certainly not a hydroxamic acid) but rather is S-hydroxyquinoline. ... 

The chemistry of hydroxylamines, oximes and hydroxamic acids / edited by Zvi Rappoport and Joel Liebman. p. cm.—(The Chemistry of Functional Groups)... 

The present book, The Chemistry of Hydroxylamines, Oximes and Hydroxamic Acids, deals with the chemistry of three related functional groups that were not hitherto treated in The Chemistry of Functional Groups series. Professor Artem Melman, then at the Hebrew University, who felt that such a book would be valuable, suggested the title and we followed his advice he also contributed a chapter. We will be grateful to other readers who suggest other topics which, in their opinion, deserve to be included in new volumes in the series. 

Mercaptoacyl pharmacophore library. Zinc metalloproteases are inhibited by small molecules that contain mercaptans (thiols -CH2SH), carboxylic acids (-CO2H), and hydroxamic acids (-CONHOH). These functional groups chelate the active-site metal disrupting normal enzyme function. The angiotensinconverting enzyme (ACE) inhibitor Captopril is an example of a thiol-based metalloprotease inhibitor. Thiols, carboxylic acids, and hydroxamic acids are consequently affirmed pharmacophores for this protease family. A historical example of a pharmacophore-... 

The preference of hydroxamic acids to form metal complexes through the hydroxamide functional group (1) and not through the hydroxyoxime structure (2) is confirmed by IR,27,28 UV,29 ESR30 and NMR28 spectral studies. Hydroxamic adds bind metal ions to form complexes with structure (3) rather than structure (4), for which evidence has been claimed31 in one case only. 

Cleavage of one specific functional group, such as a carboxylic ester, hydroxamate or amide. This strategy is especially useful to produce focused or targeted libraries. 

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