NUCLEIC-ACID RELATED-COMPOUNDS .86. NUCLEOPHILIC FUNCTIONALIZATION OFADENINE, ADENOSINE, TUBERCIDIN, AND FORMYCIN DERIVATIVES VIA ELABORATION OF THE HETEROCYCLIC AMINO GROUP INTO A READILY DISPLACED 1,2,4-TRIAZOL-4-YL SUBSTITUENT

Treatment of 9-methyladenine and hydroxyl-protected derivatives of ade nosine and 2'-deoxyadenosine with 1,2-bis[(dimethylamino)methylene] hy drazine and/or its dihydrochloride at elevated temperatures in appropr iate solvents resulted in elaboration of the 6-amino group into a 6-(1 ,2,4-triazol-4-yl) substituent in excellent yields. Analogous function alization of the amino groups of tubercidin 7-(beta-D-ribofuranosyl)py rrolo[2,3-d]-pyrimidine} and formycin 3-(beta-D-ribofuranosyl)pyrazolo [4,3-d]pyrimidine} gave the respective 4- and 7-(1,2,4-triazol-4-yl) d erivatives. Nucleophilic replacement of the triazole moiety gave the r espective 6-, 4-, and 7-substituted purine, pyrrolo[2,3-d]pyrimidine, and pyrazolo[4,3-d]pyrimidine products. This first general method for ''direct'' nucleophilic replacement of an amino group on these nitroge n heterocycles also provides a new class of compounds for potential po stsynthetic modifications after incorporation into oligonucleotides.