- Heterocyclic Ambident Nucleophiles. III* The Alkylation of Sodium Adenide
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The alkylation of sodium adenide in HCONMe2 (30 deg) with various alkylating agents was analysed by 1H n.m.r. spectroscopy.Widely varying N3:N7:N9 alkylation patterns were observed, depending on the alkylating agent.These patterns are interpreted in terms of the electrostatic, thermodynamic and steric factors involved in the different SN2 transition states appropriate to each alkylating agent.Hydrogen bonding association between the 6-amino group and certain carbonyl containing alkylating agents is proposed to explain the enhancedN7-alkylation in some cases.Support for this latter proposal was obtain from a comparison of the adenine alkylation results with the corresponding alkylation patterns of 6-pivaloylamino- and 6-chloro-purine.
- Rasmussen, Malcolm,Hope, Janet M.
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p. 525 - 534
(2007/10/02)
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- Heterocyclic Ambident Nucleophiles. IV* The alkylation of Metal Salts of Adenine
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The N3:N7:N9 alkylation patterns for reactions of the lithium, sodium, and potassium salts of adenine with various alkylating agents in dimethyl sulfoxide were determined by 1H n.m.r. spectroscopy.Only for the Li+ salt was any significant effect of ionic association noticed.Of the alkylating agents used, only chloromethyl pivalate gave a concentration dependent alkylation pattern.The latter effect was most pronounced with the heterogenous alkylation conditions of anhydrous Na2CO3/HCONMe2, adenine, and chloromethyl pivalate; here, increasingconcentrations changed the main reaction from N7- to N9-alkylation.Solvent effects on the alkylation patterns were also studied.Within the common dipolar aprotic solvent group, (Me2N)3PO, HCONMe2 and Me2SO, effects were small; in protic solvents, particularly formamide, enhanced N3-alkylation was observed.
- Rasmussen, Malcolm,Hope, Janet M.
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p. 535 - 542
(2007/10/02)
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- Phase-Transfer Catalysis in the N-Benzylation of Adenine
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A convenient phase-transfer catalysis in the N-benzylation of adenine is described.The benzylation of adenine with benzyl halides in a two-phase system containing phase-transfer catalyst gave 9-benzylated adenines as a major product accompanied with 3-benzylated adenines.
- Shinkai, I.,Zwan, M. C. Vander,Hartner, F. W.,Reamer, R. A.,Tull, R. J.,Weinstock, L. M.
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p. 197 - 198
(2007/10/02)
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