Synthesis, characterisation and theoretical calculations of 2,6-diaminopurine etheno derivatives

Abstract

Four derivatives of 2,6-diaminopurine (1) were synthesised and characterised. When 1 was reacted with chloroacetaldehyde, 5-aminoimidazo[2,1-i]purine (2), 9-aminoimidazo[2,1-b]purine (3), 9-aminoimidazo[1,2-a]purine (4) and diimidazo[2,1-b:2′,1′-i]purine (5) were formed. The purified products (3–5) were fully characterised by MS, complete NMR assignments as well as fluorescence and UV spectroscopy. The purified, isolated yields of these products (3–5) varied from 2.5 to 30%. The relative stability of different tautomers was investigated by theoretical calculations. Fluorescence characteristics are also discussed and compared to the starting material 1 and a reference molecule 2-aminopurine.