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 degrees 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 degrees C.