To improve the stability and pharmacokinetic properties,prodrugs of L-ddG（L-2＇,3＇-dideoxy-guanosine）and L-D4G （L-2＇,3＇-dihydro-2＇,3＇-dideoxyguanosine）modified with a series of substituted amino groups at C-6 position of the purine base were designed and synthesized and their anti-HIV activities were evaluated.Compounds 7d and 8g exhibited moderate activity and showed EC_（50）of 42μmol/L and 55μmol/L,respectively.
3-Deazaneplanocin A （3-DNPA, 2）, an antiviral and antitumor agent, has been synthesized in an optimized procedure in 10 steps, with an increased overall yield of 11.2%. Started from 2,4-dihyroxyl-3-nitropyridine, reduction of nitro group and ring closure of imidazole were carried out in one pot, without the separation of diaminopyridine （10）, to give 3-deazapurine （11）. Moreover, the conversion of 6-chloro-3-deazapurine （12） to 6-amino-3-deazapurine （13） and the synthesis of N^6,N^6,N9-tris-Boc-3- deazadenine （16） was promoted by microwave-aid method. Compound 16 benefited the formation of N9 isomer of 3-DNPA in Mitsunobu reaction.
