Amino groups relative reactivity

The 0X0 group facilitates reaction relative to H, CH3, or NH2 substituents on pyrimidines in the displacement of mercapto, arylthio, or amino groups by amines. The 2-thioxo group is reactive toward... 

In contrast to the lability of certain dN adducts formed by the BHT metabolite above, amino acid and protein adducts formed by this metabolite were relatively stable.28,29 The thiol of cysteine reacted most rapidly in accord with its nucleophilic strength and was followed in reactivity by the a-amine common to all amino acids. This type of amine even reacted preferentially over the e-amine of lysine.28 In proteins, however, the e-amine of lysine and thiol of cysteine dominate reaction since the vast majority of a-amino groups are involved in peptide bonds. Other nucleophilic side chains such as the carboxylate of aspartate and glutamate and the imidazole of histidine may react as well, but their adducts are likely to be too labile to detect as suggested by the relative stability of QMs and the leaving group ability of the carboxylate and imidazole groups (see Section 9.2.3). 

By varying all the parameters of the process the authors prepared a set of copolyesters containing units and blocks with a tertiary amino group, which, in turn, could be transformed into a hydrophilic hydrochloride salt thus imparting water-compatibility to the initially organosoluble macromolecules. The principle involved was the formation of a block-type structure of chains in order to facilitate their further protein-like folding in an aqueous medium. It was shown that the main factors responsible for the blockiness were the relative reactivities of the (B) and (C) components (NMDEA and bisphenol) and the order of their addition to the reaction. 

Serine esters can be O-alkylated without concomitant A -alkylation, when the amino group is protected as its trityl derivative. The reaction is generally high yielding under relatively mild conditions [33], particularly with the more reactive allyl and benzyl halides. 

Friedman, M., Cavins, I.F., and Wall, l.S. Relative nucleophilic reactivities of amino groups and mercaptide ions in addition reactions with a.p-unsaturated compounds, J. Am. Chem. Soc., 87(16) 3672-3682,1965. 

The V-hydroxysuccinimide that is liberated is easily removed because of its solubility in dilute base. The relative stability of the anion of V-hydroxysuccinimide is also responsible for the acyl derivative being reactive toward nucleophilic attack by an amino group. 

Acy 1-4-amino-1,5-dihydro-2-pyrrolones (6) (type Z in Scheme 1) possess the features of cyclic enaminediones. The push-pull-7r system decreases the nucleophilicity of the amino group. Therefore N-acylation with carboxylic acid chlorides requires relatively drastic conditions (dioxane, 100°C, K2C03). In particular, the reaction of the highly reactive DMF-acetal 8 to formamidine 9 succeeds only while refluxing in benzene (87TH1). (See Fig. 3.)... 

Using the data of Wilson and Cannan (18), Cleaves (81) was able to show that the rate of formation of pyrrolidone carboxylic acid from glutamic acid in aqueous solution depends directly on the concentration of the ionic species of glutamic acid in solution. Thus, the reactive species are (I), (II), and (IV), while (III) is relatively unreactive. Protonation of the amino group and dissociation of the y-carboxyl group thus makes these groups less reactive carboxylate ion resonance apparently hinders nucleophilic attack by the amino nitrogen. 

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