An investigation of the alkaline phosphatases for use in organic synthesis.

The synthesis of a series of 1-phenylalkyl-l-phosphate analogues is described as well as the preparation of 2-phenylpropyl-1-phosphate, 2,3-dimethylbutyl-1-phosphate, 3-methyl-2-butyl-2-phosphate, 1-(para-methoxyphenyl)ethyl-1-phosphate and l-(para-nitrophenyl)ethyl-1-phosphate. The enantioselectivities of bovine, rabbit and E.coli alkaline phosphatases with these various substrates were investigated. Bovine alkaline phosphatase showed the best enantioselectivity with 1-phenylethyl-1-phosphate showing an enantiomeric excess of 56% favouring the turnover of (R)-1-phenylethyl-1-phosphate enantiomer. Attempts to improve the enantioselectivity of bovine alkaline phosphatase with 1-phenylethyl-1-phosphate by varying the reaction conditions was undertaken. These included changes in pH and sodium chloride concentration. The addition of organic solvents to the buffer solutions as well as changes in the zinc and magnesium ion concentrations were studied. Detailed analyses of the kinetic parameters of the individual enantiomers (1R)-phenylethyl-1-phosphateand (1S)-phenylethyl-1-phosphate with bovine and E. coli alkaline phosphatase were carried out. The results of these investigations were used to try to enhance the enantioselectivities of the bovine and E. coli phosphatases with 1-phenylethyl-1-phosphate. Synthesis of a series of 2-alkylpropyl-1,3-bisphosphate from their 2-alkyl-1,3-propanediol derivatives is described. The prochiral selectivities of this series of 2-alkylpropyl-1,3-bisphosphates were evaluated with bovine alkaline phosphatase. Failure to isolate the desired monophosphate products prevented further use of the alkaline phosphatases to effect enantiotopic discrimination of the prochiral 1,3-bisphosphates. Inhibition studies of these materials with bovine and E. coli phosphatases were therefore carried out.