Esters aryl, aminolysis

Noting the fairly pronounced reactivity of phenyl esters in aminolysis Bodanszky concluded [21] that the enhanced aminolysis rates observed with thiophenyl esters [4] are due only in part to their thiol ester character and perhaps to a major extent to the fact that they are aryl esters. This conclusion was based on the fundamental studies of Gordon, Miller and Day [22] who found extremely high rates in the ammonolysis of phenyl and vinyl esters. To further increase the electronic effect operative in phenyl esters, their nitro-derivatives were prepared and examined. For practical application p-nitrophenyl esters were... 

Detailed mechanistic studies have been carried out on aminolysis of substituted aryl acetates and aryl carbonates. Aryl esters are considerably more reactive than alkyl esters because the phenoxide ions are better leaving groups than alkoxide ions. The tetrahedral intermediate formed in aminolysis can exist in several forms which differ in extent and site of protonation ... 

Alkanesulfonyl halides are not the only alkanesulfonyl derivatives that can undergo substitution by an elimination-addition mechanism. A number of aryl esters of phenylmethanesulfonic acid, PhCH2SOzOAr, undergo alkaline hydrolysis and aminolysis by such a pathway, and study of these reactions has been particularly valuable in providing insight into the detailed mechanism for sulfene formation (Williams et al., 1974 King and Beatson, 1975 Davy et al., 1977). 

M. I. Page, D. Render, G. Bemath, Stereochemical Studies. Part 112. Geometrical Dependence of Intramolecular Catalysis in the Hydrolysis and Aminolysis of Aryl Esters , J. Chem. Soc., Perkin Trans. 2 1986, 867-871. 

Aminolysis of phenyl dithioacetates,8 pyridinolysis of O-ethyl dithiocarbonates,9 reaction of pyrrolidine with O-ethyl 5-aryl dithiocarbonates,10 aminolysis of chlorothionformates,11 pyridinolysis of alkyl aryl thioncarbonates,12 reaction of anionic nucleophiles with nitrophenyl benzoate and its sulfur analogues,36 hydrolysis of methyl benzoate and phenyl acetate containing SMe, SOMe and S02Me substituents,42 solvolysis of phenyl chlorothioformate,79 synthesis of new thiadiazoles,124 examination of a neighbouring sulfonium group in ester hydrolysis,136 hydrolysis of V-type nerve agents,250 and the reactions of peroxymonosulfate ion with phosphorus(V) esters have all been looked at previously in this review. 

Solvolysis rates of isopropenyl chloroformate, CH2=C(Me)0C(0)Cl, were shown to be very similar to those for 4-nitrobenzoyl chloride in mechanism and reactivity.29 Stepwise mechanisms were observed in the aminolysis of aryl chloroformates by a series of substituted quinuclidines - which were more reactive than isobasic secondary alicyclic amines.30 The pH-independent hydrolysis of 4-nitrophenyl chloroformate in MeCN-H20 mixtures proceeded via a cyclic transition state containing the ester and two water molecules.15 Solvolyses of 2-furancarbonyl chloride in most... 

It seems probable that the mechanism of ester aminolysis is similar to that of the reaction between amines and aryl halides, a reaction which also exhibits general base catalysis (see section III.C). The reaction would then involve the formation of a tetrahedral intermediate (2) by addition of amine across the carbonyl double bond in an equilibrium step, which can then decompose via two independent pathways, one catalysed by base (A ) and the other not (/ 3). Whether... 

The reaction of p-nitrophenyl acetate with 1,3-diaminopropane in chlorobenzene is intramolecularly catalysed [72]. The reaction of n-butylamine with p-nitrophenyl acetate in chlorobenzene is second order (kj) in amine and no reaction which is first order in amine was detected. In contrast, the reaction with 1,3-diaminopropane has both terms of first and of second-order in amine, and the rate constant for the reaction which is first-order in amine is at least 300 times greater than that for the undetected reaction of n-butylamine, while the rate constant for the reaction which is second-order in amine is about 14 times greater than the analogous reaction of n-butylamine [72]. Since breakdown of the tetrahedral intermediate is rate-limiting in the aminolysis of aryl esters in aprotic solvents [32], the intramolecular catalysis presumably functions in this step, possibly as symbolized by 46. 

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