Photolabile Precursors of Cyclic Nucleotides with High Aqueous Solubility and Stability

Photolabile phosphotriester derivatives of cyclic AMP and cyclic GMP are described, where the additional group on the phosphate is a 2-nitrobenzyl that bears an electron-withdrawing and dianionic substituent. This confers high aqueous solubility and excellent resistance to hydrolysis of the phosphotriester (t 1/2 for hydrolysis at pH 7, 22 °C, is >3 months for the axial isomers 3a and 4a and >1 month for the equatorial isomers 3b and 4b). The photolysis quantum yields are in the range 0.15−0.24, and the product release rate upon flash photolysis is 1.7 s-1 at pH 7.0, 20 °C.