The syntheses of novel tricyclic pyrrolo[2,3-d]pyrimidine analogues of S6-methylthioguanine are described. The crystal structures and pKa values of these and related O6-methylguanine analogues are reported. All compounds display higher pKa values than O6-methylguanine with the sulfur-containing analogues being the more basic and exhibiting higher stability in aqueous solution. In a standard substrate assay with the human repair protein O6-methylguanine-DNA methyltransferase (MGMT) only the oxygen-containing analogue displayed activity.

The syntheses of novel tricyclic pyrrolo[2,3-d]pyrimidine analogues of O(6)-methylguanine and S(6)-methylthioguanine are described. The crystal structures and pK(a) values of these analogues are reported. In a standard substrate assay with the human repair protein O(6)-methylguanine-DNA methyltransferase (MGMT) only the oxygen-containing analogue displayed activity.

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6 refs.]. -(HORNILLO-ARAUJO, A. R.; BURRELL, A. J. M.; AIERTZA, M. K.; SHIBATA, T.; HAMMOND, D. M.; EDMONT, D.; ADAMS, H.; MARGISON, G. P.; WILLIAMS*, D. M.; Nucleosides, Nucleotides Nucleic Acids 26 (2007) 8-9, 1099-1102; Dep. Chem., Univ. Sheffield, Sheffield S3 7HF, UK; Eng.) -Schulze 12-252