A new and more efficient method is presented for the synthesis of 13C(8)-enriched adenine. In addition, we present for the first time the synthesis of 13C(8)-enriched 2-aminopurine and purine. All three analogues have been converted to the corresponding ribonucleosides. The adenine analogue has been further converted to the 2'-deoxy-nucleoside and incorporated into a synthetic oligonucleotide. Data is presented demonstrating the utility of 13C-enrichment in heteronuclear isotope-edited NMR spectra.