Exploratory studies to investigate a linked prebiotic origin of RNA and coded peptides. 3rd communication. Behaviour of 5-amino-1H-imidazole-4-carbonitrile derivatives

Abstract

The potentially prebiotic synthesis of pyrimidine ribonucleotides by stepwise nucleobase assembly on arabinose-3-phosphate derivatives has been demonstrated in previous work. The generation of xylose-2-phosphate derivatives by aldolisation, and the behaviour of these compounds under the conditions of pyrimidine nucleobase assembly have also been described. In this paper, the scope for generation of purine nucleotides via 3,3'-anhydro-xylo-nucleotides is investigated. In neutral D2O solution, the potential intermediate 47 (Schemes 6 and 8) undergoes H-C2 --> D-C2 exchange, but no appreciable reaction with cyanide or cyanamide occurs. The exchange chemistry expands options for purine nucleobase assembly on sugar phosphate scaffolds.