NEW ACYCLIC PURINE NUCLEOSIDE ANALOGS CONTAINING EXOCYCLIC PYRROLO MOIETY - SYNTHETIC, NMR AND X-RAY CRYSTAL-STRUCTURE STUDIES

The synthesis of novel 6-(N-pyrrolyl)purine nucleoside analogues conta ining acyclic side chains attached to the purine ring at N-9 is descri bed. The structures were determined by H-1 and C-13 NMR on the basis o f chemical shifts, substituent induced shifts, C-H coupling constants and connectivity in the COSY, NOESY and HET-COR spectra. Unequivocal p roof for the stereostructure of 6 was obtained by its X-ray crystallog raphic analysis. Geometrical data from X-ray structural analysis showe d that the two 6-(N-pyrrolyl)purine rings involved in the skeleton of 6 are anti-disposed but not centrosymmetric with respect to the centra l aliphatic bridge.