The photolabile and fluorescent system 1 was prepared via a convergent
route which involved thymidine 3'-functionalized with a proline resid
ue. Photodecomposition of 1 was examined using 360 nm irradiation. Wit
hout any additives, 5'-silylated thymidine was not formed, but the N-a
lpha-deprotected cyclization precursor II accumulated instead. However
, in the presence of ethanolamine, 5'-silylated thymidine formed at a
rate which increases with the concentration of ethanolamine.