Reaction of 4-picoline(2,2′ :6′,2″-terpyridine)platinum(II) with nucleosides

Abstract

The four nucleosides found in DNA react with 4-picoline(2,2′ :6′,2″-terpyridine)platinum(II). Guanosine and 2′-deoxyguanosine are platinated at N⁷. Adenosine and 2′-deoxyadenosine are platinated at both N¹ and N⁶ with loss of a proton and there is no evidence of monoplatinated intermediates. It is proposed that platination occurs initially at N¹, the most nucleophilic site, which leads to loss of a proton from the N⁶ amino function and subsequent rapid platination at this site. This conclusion is supported by NMR and mass spectral evidence. 2′-Deoxycytidine is similarly platinated at N³ and N⁴ and a similar explanation is proposed. Platination of thymidine is very slow and the product(s) has not been characterised.