title: Structure of cyclic nucleoside phosphonate ester prodrugs: an inquiry.
abstract: The configuration at phosphorus in cyclic (S)-HPMPC (1, cidofovir) and (S)-HPMPA (2) phenyl ester (5 and 6, respectively) diastereomers ((R(p))-5, (R(p))-6, (S(p))-6) was determined by X-ray crystallography and correlated to their (1)H and (31)P NMR spectra in solution. (R(p))-5 and (R(p))-6 have chair conformations with the nucleobase substituent equatorial and the P-OPh axial. Perhaps surprisingly, (S(p))-6 is (a, a) in the crystal and exists largely as an equilibrium of (a, a)/(e, e) conformers in chloroform or acetonitrile.
authors: Department of Chemistry, University of Southern California, Los Angeles, California 90089-0744, United States.
authors: Ivan S
authors: IS
authors: Krylov
authors: Valeria M
authors: VM
authors: Zakharova
authors: Michaela
authors: M
authors: Serpi
authors: Ralf
authors: R
authors: Haiges
authors: Boris A
authors: BA
authors: Kashemirov
authors: Charles E
authors: CE
authors: McKenna
mesh_terms: D000097:Acetonitriles / Q000737:chemistry; D002725:Chloroform / Q000737:chemistry; D000077404:Cidofovir; D018360:Crystallography, X-Ray; D003596:Cytosine / Q000031:analogs & derivatives* / Q000737:chemistry; D004952:Esters; D009682:Magnetic Resonance Spectroscopy; D008968:Molecular Conformation; D015394:Molecular Structure; D009705:Nucleosides / Q000737:chemistry*; D063065:Organophosphonates / Q000737:chemistry*; D011355:Prodrugs / Q000737:chemistry*; D013237:Stereoisomerism
chemical_list: D000097:Acetonitriles; D004952:Esters; D009705:Nucleosides; D063065:Organophosphonates; D011355:Prodrugs; D002725:Chloroform; D003596:Cytosine; D000077404:Cidofovir; C032159:acetonitrile