7-(Carboxymethyl)-6-chloropurine Ethyl Ester

Alkylation of 6-chloropurine using ethyl brombacetate gives a mixture of regioisomers from which the title compound, C 9 H 9 ClN 4 O 2 , was isolated in crystalline form. The ethyl acetate fragment attached at N7 avoids steric hindrance by emerging from the ring almost orthogonally. Two ring C atoms donate weak intermolecular hydrogen bonds to the carbonyl O12 and ring N3 atoms.