Catalytic hydrolysis, intramolecular

In aqueous Brij35 micellar solution, the copper(II) complex of macrocyclic Schifif base can only catalyze the hydrolysis of 1 by the mechanism that involves the nucleophilic attack of external hydroxide ion on the carbonyl carbon of substrate (ester), whereas the zinc(II) complex of same ligand can accelerate the hydrolysis of 1 more strongly than that of 4-nitrophenyl acetate by the intramolecular nucleophilic attack of zinc-bound hydroxide ion on carbonyl carbon of esters. The catalytic activity of Zn(II) complex is close to or higher than that of Cu(II) complex. The rate constants for the catalytic hydrolysis of bis(4-nitrophenyl) phosphate by complexes [(bpya)Cu]Cl2 and [(bpya)Zn]Cl2 (where bpya = 2,2 -dipyridylamine) in Brij35 micellar solution at 25°C and pH 7.02 are 1.2 X 10 times and 1.5 x 10 times higher than those for the spontaneous hydrolysis, respectively. ... 

Yet another distinction is between intermolecular catalysis, in which the catalytic function and the reaction site are on different molecules, and intramolecular catalysis, in which the catalytic function and the reaction site are within the same molecule. All of the above examples constitute intermolecular catalyses. The following reaction, the hydrolysis of a monomaleate ester, is an intramolecular nucleophilic catalysis. 

When 1,2-diols are subjected to the same reaction conditions required for the formation of sulphonic esters, oxiranes are produced [27]. Presumably, the mono ester is initially formed and, under the basic conditions, intramolecular elimination occurs to produce the oxirane. Partial hydrolysis and ring-closure of a,p-di(tosyloxy) compounds under basic phase-transfer catalytic conditions provides a convenient route to carbohydrate oxiranes [e.g. 28, 29]. Oxiranes have been produced by an analogous method via carbonate esters from partially protected carbohydrates [30],... 

In another estimate (Kirby and Percy, 1989), the carboxyl group in l-methoxymethoxy-8-naphthoic acid and the dimethylammonium group in the l-methoxymethoxy-8-A, A -dimethylnaphthylammonium ion are estimated to lead to rate increases by intramolecular catalysis of < ca. 900 and 1.9 X 10 compared to the value of ca. 1 x 10 calculated for the intramolecular catalytic effect of the carboxyl group in 2-methoxymethoxybenzoic acid. The salicylate ion remains the most efficient leaving group thus far discovered that can take part in hydrogen-bond catalysis of the hydrolysis of acetals. 

What is the effective molarity of imidazole as an intramolecular general base in intramolecular alcoholysis and hydrolysis This is perhaps the most important single piece of information that is currently missing for analysis of the rates of a-chymotrypsin reactions in terms of specific catalytic effects. 

The intramolecular C-H insertion reaction of phenyldiazoacetates on cyclohexadiene, utilizing the catalyst Rh2(S-DOSP)4, leads to the asymmetric synthesis of diarylacetates (Scheme 8). Utilizing the phenyl di azoacetate 38 and cyclohexadiene, the C-H insertion product 39 was produced in 59% yield and 99% ee. Oxidative aromatization of 39 with DDQ followed by catalytic hydrogenation gave the diarylester 40 in 96% ee. Ester hydrolysis followed by intramolecular Friedel-Crafts gave the tetralone 31 (96% ee) and represents a formal synthesis of sertraline (5). Later studies utilized the catalyst on a pyridine functionalized highly cross-linked polystyrene resin. ... 

Sorm and Beranek39 used an intramolecular acylation in their synthesis of l-azoniumtricyclo[3.3.3.0]undecane (66). Condensation of nitromethane with acrylonitrile in the presence of an alkaline catalyst resulted in the formation of tris-(2-cyanoethyl)nitromethane (60), which afforded the triethyl ester 61 on hydrolysis followed by esterification. The ester was reduced catalytically to give a pyrrolidone (62). The derivative (62) gave rise to 8-(j8-carboethoxyethyl)-3,5-dioxo-pyrrolizidine (63) on heating. Reduction of 63 resulted in the formation of 8-(y-hydroxypropyl)pyrrolizidine (64). Replacement of the hydroxy group by bromine (65), followed by cyclization, afforded the tricyclic compound 66. 

Divalent metal ions inhibit the hydrolysis of N-(2-pyridyl)phthalamic acid (60) and N-(2-phenanthrolyl)phthalaxnic acid (61). In the case of (61) the substrate hydrolyzes by a pathway involving intramolecular general acid catalysis, and this pathway is inhibited by metal ions. Deprotonated amide complexes may also be involved leading to catalytically inactive complexes. 

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