Structure of Cyclic Nucleoside Phosphonate Ester Prodrugs: An Inquiry
作者:Ivan S. Krylov、Valeria M. Zakharova、Michaela Serpi、Ralf Haiges、Boris A. Kashemirov、Charles E. McKenna
DOI:10.1021/jo201735f
日期:2012.1.6
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 H-1 and P-31 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.