Proof of the imidoyl phosphate intermediate for oxidative phosphorylation in [18O]dimethylformamide solution

Abstract

The bromine oxidation of 2-methylnaphthalene-1,4-diol diphosphate in anhydrous [¹⁸O]-dimethylformamide resulted in orthophosphate enriched in oxygen-18. Appropriate controls showed no exchange. The observed incorporation indicated 26% formation of the imidoyl phosphate intermediate, Me₂NCH·O·PO₃H^–, derived by solvation of monomeric metaphosphate from P–O bond fission.

The 2-methyl-1,4-naphthaquinone produced in this oxidation was also enriched in oxygen-18, corresponding to 5% formation of intermediate solvated ketal analogues from C–O cleavage.

The [¹⁸O]-dimethylformamide was prepared by direct exchange with enriched water.