A convenient general procedure for the conversion of alcohols into their monophosphate esters

Abstract

o-Phenylene phosphorochloridate (IV), readily prepared from catechol in good yield, reacts rapidly and quantitatively with stoicheiometric amounts of alcohols (including tertiary alcohols) in the presence of a suitable base (triethylamine or 2,6-lutidine) and in a suitable solvent (dioxan, tetrahydrofuran, or benzene). Alkyl o-hydroxyphenyl phosphate salts (IX) were thus obtained in virtually quantitative yields, and sometimes as pure crystalline compounds.The phosphodiesters (IX) were converted into the corresponding monoalkyl phosphates (II) by treatment with (a) bromine in neutral aqueous buffer solution, (b) periodic acid in aqueous solution, or (c) lead tetra-acetate in dioxan solution, followed by alkaline hydrolysis. The products were easily isolated as pure barium salts. In this way, the barium salts of t-butyl, neopentyl, 2,2,2-trichloroethyl, 2,2,2-tribromoethyl, 2-cyanoethyl, and allyl phosphates have all been prepared in good overall yields. The pure barium salts of 1,1- and 3,3-dimethylallyl phosphates have also been prepared, albeit in lower yields.