Synthesis, structure and redox properties of ferrocenylmethylnucleobases

Ferrocenyl derivatives of thymine 1, cytosine 2, and uracil and of N2-acety lguanine and 2-amino-6-chloropurine have been prepared from reactions of [F e(eta(5)-C5H5)(eta(5)-C5H4CH2N(CH3)(3))] I with the corresponding pyrimidin e or purine base. The predominant site of alkylation for thymine and cytosi ne was N1 while for uracil N3 was preferred. Alkylation of the guanine prec ursor 2-amino-6-chloropurine yielded two products, the N2-monosubstituted, and the N2,N9-disubstituted, derivatives. Acetyl protection/deprotection of the N2 amino group allowed selective N9-alkylation to yield 2-amino-6-chlo ro-9-ferrocenylmethylpurine. With N2-acetylguanine alkylation occurred at e ither the N7 or N9 positions in a approximate to 3 : 1 ratio. The structure s of eight compounds were determined by single crystal X-ray analysis. Elec trochemical investigations by cyclic voltammetry revealed reversible redox processes for the compounds.