Download full text in PDF Opens in a new window. Article suggestions will be shown in a dialog on return to ScienceDirect. ... Please enable JavaScript to use all the features on this page. ... Selective coupling in the purine 6-position has been achieved, by reacting N-benzylated 2,6-dichloropurines with organotin and organozinc reagents. The positional identity products were established from long range HETCOR or nOe NMR experiments.