title: Photochemistry and thermal decarboxylation of alpha-phosphoryloxy-p-nitrophenylacetates.
abstract: Alpha-carboxy-4-nitrobenzyl phosphate 4 and its derived monomethyl phosphate ester 5 were synthesized and purified by anion-exchange chromatography. A gradient of LiCl was necessary for elution of the anion-exchange column to avoid unexpected thermal decarboxylation that occurred during vacuum evaporation when the volatile triethylammonium bicarbonate buffer was used. Photolysis of each compound was accompanied by decarboxylation, and 4 released inorganic phosphate with near-100% stoichiometry. Time-resolved infrared spectroscopy of the photolysis reaction, coupled with density functional theory calculations of vibrational frequencies, enabled us to infer a mechanism for the photolytic pathway, although there was some evidence for a second pathway also being operative. In contrast to the results for 4, photolysis of 5 appeared to release little or no monomethyl phosphate.
authors.affiliation: MRC National Institute for Medical Research, London, UK.
authors.forename: John E T
authors.initials: JE
authors.lastname: Corrie
authors.forename: V Ranjit N
authors.initials: VR
authors.lastname: Munasinghe
authors.forename: Maria
authors.initials: M
authors.lastname: Rudbeck
authors.forename: Andreas
authors.initials: A
authors.lastname: Barth
mesh_terms: D002264:Carboxylic Acids / Q000737:chemistry*; D002852:Chromatography, Ion Exchange; D006358:Hot Temperature; D010648:Phenylacetates / Q000737:chemistry*; D010777:Photochemistry
chemical_list: D002264:Carboxylic Acids; D010648:Phenylacetates; C025136:phenylacetic acid