Hydroxamic acid benzyl esters

Imidazoles from purines o-Aminocarboxylic acid amides from pyrimidine ring Carboxylic acid amides from hydroxamic acid benzyl esters... 

Aldehyde 54 and the hydroxamic acids 55 were generated together in an acid-catalysed elimination reaction (Scheme 7 pathway (ii)). A crossover experiment indicated that esters are formed in a concerted rearrangement concomitant with the likely formation of the hydroxynitrene 57 (Scheme 7 pathway (iii)) while there is no evidence to date for the formation of hydroxynitrene, joint solvolysis of equimolar quantities of /V-acetoxy-/V-butoxy-/>-chlorobenzamide 26e and N- acetoxy-/V-benzyloxybenzamide 27a afforded significant quantities of butyl p-chlorobenzo-ate (36%) and benzyl benzoate (54%) as the only esters. This is an example of a HERON reaction, which has been identified in these laboratories as a characteristic rearrangement of bisheteroatom-substituted amides.32,33,42 43 155 158 Since ester formation was shown to prevail in neutral or low acid concentrations, it could involve the conjugate anion of the hydroxamic acid (vide infra).158... 

S Additional information <9, 15, 17, 18, 21, 24, 30, 33, 35> (<18> activity is regulated by light [28] <30> D-aspartate, L-glutamate and -alanine are inactive as substitutes for L-aspartate in the forward reaction, in the reverse reaction ADP cannot be replaced by AMP, UDP, GDP or IDP [1] <17> aspartokinase III, o-isomers of the derivatives of aspartic acid, including D-aspartate cr-benzyl ester and o-aspartate /)-hydroxamate are not substrates regardless of whether the a- or the -carboxyl group is derivatized, L-cysteine sulfinate and 2-methyl-DL-aspartate are no substrates... 

Recently Benkovic and Schrayl28b and Clark and Kirby,26c have investigated the hydrolysis of dibenzylphosphoenolpyruvic acid and mono-benzylphospho-enolpyruvic acid which proceed via stepwise loss of benzyl alcohol (90%) and the concomitant formation of minor amounts (10%) of dibenzylphosphate and monobenzylphosphate, respectively. The pH-rate profiles for release of benzyl alcohol reveal that the hydrolytically reactive species must involve a protonated carboxyl group or its kinetic equivalent. In the presence of hydroxylamine the course of the reaction for the dibenzyl ester is diverted to the formation of dibenzyl phosphate (98%) and pyruvic acid oxime hydroxamate but remains unchanged for the monobenzyl ester except for production of pyruvic acid oxime hydroxamate. The latter presumably arises from phosphoenolpyruvate hydroxamate. These facts were rationalized according to scheme (44) for the dibenzyl ester, viz. 

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