Attachment of Sugar Phosphates and Nucleotide Derivatives to Pyrazolylborate-Zinc Units

Abstract

Phosphate derivatives which model intermediates of enzymatic glycoside and nucleotide transformations were reacted with the hydrolytically active zinc-hydroxide species Tp*Zn−OH (Tp* = 3,5-disubstituted tris(pyrazolyl)borates). Depending on the substrate or the reaction conditions, either phosphate ester cleavage or deprotonation of a nucleobase NH was observed. As a result, the Tp*Zn units were attached to the phosphate part or/and to the nucleobase part of the substrate. Nucleobase adducts were found of three uridine monophosphate derivatives. Phosphate adducts were found of a hydroxyacetone monophosphate, of a ribose phosphate, and of uridine and N-methyluridine monophosphates. The products were identified by crystallographic and spectroscopic methods as tetrahedral Tp*Zn−X complexes. Crystals of TpCum,MeZn−OPO(OC6H4NO2)(O-hydroxyacetone dimethyl ketal) are monoclinic, space group P21/n, with a = 13.221(1) Å, b = 13.738(1) Å, c = 30.303(3) Å, β = 99.57(1)°, Z = 4; those of TpCum,MeZn−OPO(OC6H4NO2)(O-2,3-isopropylidene-5-methylribose) are monoclinic, space group P21, with a = 16.179(6), Å, b = 16.206(5) Å, c = 21.192(14) Å, β = 101.02(5)°, Z = 2; those of TpPic,MeZn(H2O)−OPO(OC6H4NO2)(O-2,3-isopropylidene-5-methylribose) are triclinic, space group P1, with a = 13.106(4) Å, b = 13.676(5) Å, c = 17.021(6) Å, α = 84.10(3)°, β = 88.37(3)°, γ = 62.43(3)°, Z = 1.