A Valuable Synthetic Intermediate

2-Amino-6-chloropurine riboside (1) is a valuable synthetic intermediate for the preparation of a number of important purine nucleoside derivatives. For example, 6-thioguanosine 2 and 6-selenoguanosine 3 were prepared from a reaction of 1 and the corresponding sodium thiosulfate or potassium selenosulfate.^{1) 18}O-labeled guanosine 4 was incubated from 1 with adenosine deaminase in (¹⁸O)-water.²⁾ 2-Amino-6-ethoxypurine riboside 5 and 2-amino-N⁶-amino-N⁶-methyladenosine 6 were prepared by treatment of 1 with nucleophiles, sodium ethoxide and methylhydrazine, respectively.^3,4) 2-Amino-N⁶-substituted purine analogues, as typified by 6, were reported as anti-malarial active compounds.⁴⁾