From Hydroxamic Acids

Hydroxylamine, O-acetyl-A -benzoyl-.V-phenyl-hydroxamic acids from, 2, 506... 

Synthesis and characterization of fatty hydroxamic acids from triacylglycerides, Journal of Oleo Science 59,15-19. 

Hulcher FH (1982) Isolation and Characterization of a New Hydroxamic Acid from Pseudomonas mildenbergii. Biochemistry 21 4491... 

B. Synthesis of Hydroxamic Acids from Carboxylic Acids. 188... 

Very recently, Mordini and coworkers" have overcome the problems associated with the long reaction times that are normally required for the synthesis of hydroxamic acids from esters by performing these transformations under MW irradiation. The protective groups are also well tolerated under these reaction conditions, though a partial deprotection of the feri-butoxycarbonyl (Boc) group was observed in the reaction with Boc-proline ester. Amidic bonds and ketals also survive without any detectable decomposition. All the reactions go to completion in about six minutes, except in the case of the conversion of Boc-protected phenylalanine methyl ester, which required longer reaction times (12 min). 

Although several routes have been published for the preparation of hydroxamic acids on solid phase, these generally involve the preparation of a special linker to which hydrox-ylamine is attached. Dankwardt s approach obviates the need for special linkers or protecting groups, by displacing the desired hydroxamic acid from the resin directly using hydroxylamine, as illustrated in Scheme 86. CarboxyUc-acid-ester-linked, polymer-supported, Cbz-protected amino acids 195 (formed from 194) were displaced from the resin with aqueous hydroxylamine to provide the corresponding hydroxamic acids 196. 

Hydroxylamine, O-acetyl-N-benzoyl-N-phenyl-hydroxamic acids from, 506 Hydroxylamine ligands, 101 Hydrozirconation, 342 Hypoxanthines metal complexes, 93... 

The combinatorial approach is attractive for the synthesis of libraries of hydroxamic acids for screening as metalloenzyme inhibitors. A variety of hydroxylamine-linked resins (shown in Schemes 9-12) have been developed that allow peptide condensation reactions followed by cleavage of the hydroxamic acid from the resin. 

Tays, K. and Atkinson, J. 1998. An improved synthesis of cyclic hydroxamic acids from Gramineae. Synth. Commun. 28, 903-912... 

Perez, F. J. 1990. Allelopathic effect of hydroxamic acids from cereals on Avena sativa and A. fatua. Phytochemistry 29, 773-776... 

Petho, M. 1992. Occurrence and physiological role of benzoxazinones and their derivatives. IV. Isolation of hydroxamic acids from wheat and rye root ssecretions. Plant Physiol. Agrochem. 41, 167-175... 

N-oxidation can occur in a number of ways to give either hydroxylamines from primary and secondary amines [Eqs. (11) and (12)], hydroxamic acids from amides, or N-oxides from tertiary amines [Eq. (13)]. The enzyme systems involved are either cytochrome P450 or a flavoprotein oxygenase. Hydroxylamines may be further oxidized to a nitro compound via a nitroso intermediate [Eq. (11)]. Oximes can be formed by rearrangement of the nitroso intermediate or N-hydroxylation of an imine, that could in turn be derived by dehydration of a hydroxylamine [Eq. (11)]. N-Oxides may be formed from both tertiary arylamines and alkylamines and from nitrogen in heterocyclic aromatic systems, such as a pyridine ring. 

Crystallise the hydroxamic acid from acetic acid. [Beilstein 10 H 98.]... 

Synthesis of hydroxamic acids from aldehydes and N-sulfonylhydroxylamine also used as a color test for aldehydes (see 1st edition). 

Hydroxamic acids from carboxylic acid COCI —y CONHOH... 

A soln. of N-acetoxy-N-[l-[4-(phenylmethoxy)phenyl]ethyl]acetamide in isopropanol treated with aq. LiOH, and stirred for 30 min - N-hydroxy-N-[l-[4-(phenylmethoxy)-phenyl]ethyl]acetamide. Y 80%. This is part of a 2-step method for preparing hydroxamic acids from hydroxylamines. F.e.s. J.B. Summers et al., J. Med. Chem. 31, 1960 (1988). 

Cyclic hydroxamic acids from nitrocarboxylic acid esters O... 

RgureS. Generation of a peptidyl hydroxamic acid from a succinimide ester. 

Carboxylic acid hydrazides from carboxylic acids—Hydroxamic acids from 1-acylimidazoles—Carboxylic acid amides s. 18, 441... 

Cyclic hydroxamic acids from oxi-minocarboxylic acids. 3,5-Seco-4-norcholestan-5-on-3-oic acid 5-oxime... 

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