Phosphoryl transfer reactions dianions

A series of kinetic experiments reported by Herschlag and Jencks (7) addressed the influence of metal ions on phosphoryl transfer reactions for non-enzymic phosphoryl transfer between pyridine and carboxylate ions (and other nucleophiles). The reaction of actetate ion with phosphorylated -y-picoline monoanion and the reverse reaction of y-picoline with acetyl phosphate dianion are... 

Uncatalyzed Reactions of Phosphate Monoesters. Phosphate monoesters in physiologically relevant pH ranges exist as either the monoanion or dianion. A large body of evidence indicates that uncatalyzed phosphoryl transfer reactions of both ionic forms takes place by loose transition states that are characterized by extensive bond cleavage to the leaving group and a small degree of bond formation to the nucleophile (for reviews of the evidence, see References (3,4)). Despite loose transition states, these reactions are concerted, and free metaphosphate is not formed in protic solvents (5). 

Full details on the phosphorylation of water and alcohols by 4-nitrophenyl dihydrogen phosphate and the NfC H ) - and N(CH3) -salts of its mono- and dianion have been published 146>. Phosphoryl group transfer from the monoanion and dianion is thought to proceed via the monomeric POf ion. Addition of the sterically unhindered amine quinuclidine to an acetonitrile solution containing the phosphate monoanion and tert-butanol produces t-butyl phosphate at a faster rate than does the addition of the more hindered diisopropylethylamine. This nucleophilic catalysis of the phosphorylation reaction is also explained by the intermediacy of the POf ion. 

Ramirez and Marecek have investigated the solvolyses of 2,4-dinitrophenyl phosphate in aprotic and protic solvents and described reaction conditions that are consistent with the involvement of free metaphosphate anion 45, 46). In particular, the dianion of the reactive phosphate monoester is capable of transferring its phosphoryl group to /err-butanol whereas the monoanion of the same ester is essentially unreactive in the same reaction. Since rert-butanol is unreac-tive as a nucleophile for steric reasons, the phosphorylation of this alcohol is considered to be a diagnostic test for the involvement of the highly reactive metaphosphate anion. 

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