Desolvated phosphate ions as acyl acceptors in dipolar aprotic media. A non-enzymatic model for formation of “energy-rich” acyl phosphates

Abstract

n-Decyl phosphate, as the mono benzyltrimethylammonium salt 1, is readily acetylated by 2,4-dinitrophenyl acetate, 2, in dry acetonitrile (MeCN). Reaction is very strongly inhibited by H₂O, and acyl phosphate, 3, is not detected with >20 vol% H₂O. In these aqueous media ester 2 is hydrolyzed, probably with general-base catalysis by 1, and the acyl phosphate is also slowly hydrolyzed. Potassium dihydrogenphosphate is slowly acetylated by 2, in moist MeCN in the presence of [18]-crown-6 in heterogeneous conditions, but the yield of acetyl phosphate decreases sharply with >10 vol% H₂O. Sodium n-decyl phosphate is also acetylated by 2 in dry MeCN in the presence of [15]-crown-5. These acetylations in anhydrous media model enzymic-mediated formation of acyl and other labile phosphates.