Approach to Artificial Nucleosides from Glycoside Isothiocyanates: Synthesis of Original N‐Glycosylated Heterostructures by Cyclocondensation Reactions

Abstract

Unusual purine nucleoside analogues were synthesized, using the well‐tried methodology in heterocyclic chemistry. This result expands the scope of accessible N‐glycosylated heterocyclic structures. Pyrimidine, and bicyclic pyrimido[1,2‐a]pyrimidine nucleoside analogues were prepared from common glycoside isothiocyanate precursors. Key cyclization steps were all based on a cyclocondensation reaction involving an activated heterodienic chain. Finally, thirteen pyrimido[1.2‐a]pyrimidine nucleoside analogues 13 a‐m were synthesized with a 30% yield on average, over 8 or 9 steps from one of the isothiocyanates 4 a‐c. These elaborated targets were fully characterized.