Synthesis of Polyhydroxylated Pyrrolidinyl Analogs of Sugar Nucleotides. Experimental and Computational Studies on...

Direct coupling between polyhydroxylated pyrrolidinyl β-amino phosphonates and uridine monophosphate (UMP) yields polyhydroxylated pyrrolidinyl analogs of sugar nucleotides suitable inhibitors of N-acetyl-galactosyltransferases. β-Amino phosphonates have been synthesized in an enantiomerically pure form through the nucleophilic addition of a phosphonate to polyhydroxylated cyclic nitrones. The reaction has been studied in detail and excellent diastereoselectivities are obtained in agreement with a stereochemical model well supported by density functional theory calculations. Binding of the nucleotide analogs with N-acetylgalactosyltransferases GalNAc-T2, GalNAc-T14, and GalNAc-T16 has been studied both experimentally and computationally through molecular dynamics simulations. Saturation transfer difference nuclear magnetic resonance experiments and measurement of K_d values have been used to validate the binding model at the active site. These studies provide important information of the role of the pyrophosphate and pyrrolidinyl moieties on the observed affinity.