L. Wozniak, M. Wieczorek, J. Pyzowski
Jul 15, 1998
Citations
0
Influential Citations
27
Citations
Journal
Journal of Organic Chemistry
Abstract
The crystal and molecular structure of diastereomerically pure N4-benzoyl-2‘-deoxycytidine 3‘-O-(Se-methyl methanephosphonoselenolate (FAST-eluted) (4, R = H, B = CBz) and 5‘-O-pixylthymidine 3‘-O-(S-methyl methanephosphonothiolate (FAST-eluted) (5) have been elucidated by X-ray crystallography. The absolute configuration at the phosphorus atom in both compounds is SP. Each FAST-4‘ (R = DMT, B = CBz) and FAST-5 (R = Px, B = Thy) in the process of DBU/LiCl-assisted condensation with 3‘-O-acetyl-N4-benzoylcytidine and 3‘-O-acetylthymidine gave after deprotection (SP)-dicytidine-(3‘,5‘)-methanephosphonate and (SP)- dithymidine-(3‘,5‘)-methanephosphonate, respectively. Unambiguous assignment of the absolute configuration at the phosphorus in 4 (R = H, B = CBz) and 5 (R = Px, B = Thy) allows for stereochemical correlation and the conclusion that DBU/LiCl-assisted nucleophilic substitution at phosphorus occurs with net inversion of configuration, in contrast to our earlier erroneous deduction.5 Moreover, the kn...