| Abstract: | The synthesis of 6-selenoguanosine ( 2 ) has been accomplished by a nucleophilic displacement of the chloro group from 2-amino-6-chloro-9-(β- D -ribofuranosyl)purine ( 1 ) with either selenourea or sodium hydrogen selenide. Treatment of 2 with Raney nickel has revealed that the seleno group can be removed much easier under these conditions than the corresponding mercapto group. Alkylation of 2 with several alkylating agents occurred at the exocyclic 6-seleno group to furnish several 6-alkylseleno-2-amino-9-(β- D -ribofuranosyl)purines. Nucleophilic displacement of the 6-benzylseleno group from 2-amino-6-benzylseleno-9-(β- D -ribofuranosyl)purine ( 3c ) with sodium methoxide has been observed to occur at a faster rate than that observed for the corresponding 6-benzylmercapto derivative. A study on the relative stability between 2 and 6-seleno-9-(β- D -ribofuranosyl)purine toward basic conditions has revealed that the amino group at position two imparts an increase in stability. |
