Indirect Photo-induced Phosphorylation via a Photolabile Troika Acid C-Ester: o-Nitrobenzyl (E)-(Hydroxyimino)(dihydroxyphosphinyl)acetate

Indirect photo-induced phosphorylation of hydroxylic solvents via UV photolysis of a C-o-nitrobenzyl ester (E-9: anilinium salt) of (E)-(hydroxyimino)(dihydroxyphosphinyl)acetic acid (E-1, ‘troika acid’) is demonstrated. Comparable phosphorylation (MeOH) was observed for the dicyclohexylammonium salt (E-10). Photolysis of E-9 in 1:1 EtOH/t-BuOH gave Et-phosphate/t-Bu-phosphate in a ratio (~3:1) suggesting phosphorylation involves dissociative fragmentation of E-1 formed via photo-induced de-esterification of E-9. Broad-band (Hg-lamp), 308 nm (XeCl excimer laser) or 355 nm (YAG laser) UV irradiation of E-9 also promoted significant E→Z isomerization and concurrent photolysis leading to phosphorocyanidate. C-Me esters of E-1 and Z-1 were photo-isomerized by the 308 nm laser but not the 355 nm laser, showing that the o-nitrobenzyl group is required for photo-isomerization at 355 nm.