Phosphonate ester hydrolysis catalyzed by two lanthanum ions. Intramolecular nucleophilic attack of coordinated hydroxide and lewis acid activation

Journal Article · Wed Jul 19 04:00:00 EDT 1995 · Journal of the American Chemical Society

DOI:https://doi.org/10.1021/ja00133a013· OSTI ID:91270

Tsubouchi, A; Bruice, T C ^[1]

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1. Univ. of California, Santa Barbara, CA (United States)

(8-Hydroxy-2-quinolyl)methyl (8-hydroxy-2-quinolyl)methyl phosphonate (I) has been synthesized as a model compound and investigated in terms of catalysis of hydrolysis by two metal ions in concert. Removal of one of two 8-hydroxyquinoline ligands of I to provide (8-hydroxy-2-quinolyl)methylmethylphosphonate (II) leads to the formation of the 1:1 complex (II)La, which is hydrolytically inert but subject to catalysis by free La{sup 3+}. From thermodynamic studies of metal ion complexation and comparison of the kinetics of hydrolysis of I and II in the presence of metal ions, we conclude the following. The phosphonate ester I forms a hydrolytically active 1:2 complex (I)La{sub 2} with La{sup 3+} but inert 1:1 complexes with Zn{sup 2+}, Ni{sup 2+}, Co{sup 2+}, Cu{sup 2+}, and Al{sup 3+}. The La{sup 3+} in the (I)La{sub 2} complex serve to (i) facilitate the formation of metal ligated hydroxide as an intramolecule nucleophile; (ii) stabilize the transition state of the hydrolysis by neutralization of the phosphonate negative charge; and (iii) interact with an incipient oxyanion of the leaving alcohol. The two La{sup 3+} functions operate in concert and provide nearly 10{sup 13} rate enhancement. Consequently the 1:2 complex (I)La{sub 2}(OH{sub 2}){sub n-1}(OH) may serve as a model for the 3`-5` exonuclease reaction of E. coli DNA polymerase I. 39 refs., 7 figs., 3 tabs.

• Sponsoring Organization: USDOE
• OSTI ID: 91270
• Journal Information: Journal of the American Chemical Society, Journal Name: Journal of the American Chemical Society Journal Issue: 28 Vol. 117; ISSN JACSAT; ISSN 0002-7863
• Country of Publication: United States
• Language: English

Related Subjects

40 CHEMISTRY
ABSORPTION SPECTRA
CATALYSIS
CHEMICAL REACTION KINETICS
HYDROLYSIS
HYDROXIDES
LANTHANUM IONS
LEWIS ACIDS
PHOSPHONATES
PHOSPHONIC ACID ESTERS
SYNTHESIS