Synthesis of 2′-Iodo- and 2′-Bromo-ATP and GTP Analogues as Potential Phasing Tools for X-ray Crystallography

Ara-adenosine (adenine 9-β-D-arabinofuranoside) and ara-guanosine (guanine 9-β-D-arabinofuranoside) are converted into 2′ halogenated ATP and GTP analogues by triflation and subsequent inversion of configuration at C-2′. For the commercially unavailable ara-guanosine a short synthesis starting from guanosine is presented. The nucleotide analogues could serve for the preparation of heavy atom derivatives of ATP- and GTP-binding proteins useful for protein crystal structure determination by MIR/MAD phasing.