e.g. Filippa Pettersson or Cancer Res. 75(6) , 1102-12, (2015) or 10.1002/anie.201600521
Selective metalation of 6-methylpurines: Synthesis of 6-fluoromethylpurines and related nucleosides
…, PW Allan, JA Montgomery, JA Secrist III
Index: Hassan, Abdalla E. A.; Parker, William B.; Allan, Paula W.; Montgomery, John A.; Secrist III, John A. Nucleosides, Nucleotides and Nucleic Acids, 2003 , vol. 22, # 5-8 p. 747 - 749
Abstract A selective metalation at the 6-CH3 over C-8 of 6-methylpurine derivative 6 was observed with softer counter cation (Na+ or K+) of the base, while the harder Li+ showed no selectivity. In the presence of N-fluorobenzenesulfonamide (NFSI), this property was utilized for the synthesis of 6-fluoromethylpurine derivatives 4 and 5 as potential toxins for suicide gene therapy.
[Hassan, Abdalla E. A.; Parker, William B.; Allan, Paula W.; Secrist III, John A. Nucleosides, Nucleotides and Nucleic Acids, 2009 , vol. 28, # 5-7 p. 642 - 656]