A short synthesis of the 1,2,4-triazolo[1,5-a]pyrimidine antibiotic essramycin is described involving condensation of aminoguanidine with ethyl benzoylacetate to give an amino-1,2,4-triazole, followed by condensation with ethyl acetoacetate to form the pyrimidone ring.

Although 7-deazapurines are well known and feature in the hypermodified RNA base queuosine, and in a range of nucleoside antibiotics such as toyocamycin, a mechanistic understanding of their biosynthesis is a longstanding problem. In particular, the obligatory loss of the N-7 nitrogen atom is puzzling, and in order to address this mechanistic conundrum a novel doubly labeled purine, [2-(13)C, 7-(15)N]-adenine, has been prepared and used as a biosynthetic precursor to toyocamycin in Streptomyces rimosus. NMR spectroscopy and mass spectrometry clearly showed incorporation of (13)C but loss of (15)N in the toyocamycin produced.