X-ray structures of five variably tert-butoxycarbonyl-substituted adenines and their liquid and solid state NMR investigations

Adenine reacts selectively with di-tert-butyldicarbonate in THF in the presence of NaOH to give N9-monoBoc-adenine 1. The molecular structure and crystal packing of this and four other variably substituted Boc-derivatives of adenine were determined in solid state by means of X-ray diffraction and CP/MAS NMR experiments and characterized in liquid state by 1H, 13C, and 15N NMR spectroscopy as well. Additionally, crystal structure of inclusion compound between N6-monoBoc-adenine 5 and CHCl3 is reported. Tautomeric equilibria of mono- and disubstituted derivatives 4 and 5 in liquid state were studied by VT NMR experiments.