摘要:
A compound of the formula A, wherein R* is a chiral auxiliary, and where the configuration at the asymmetric carbon atom between oxygen and sulfur is (R), (S), or combinations of (R) and (S), useful in the preparation of enantiomerically enriched 1,3-oxathiolane nucleoside analogues, for example (−)-FTC and 3TC.
摘要:
A process for the preparation of 1,3-oxathiolane nucleoside analogues in predominantly the cis-form, from mixture of cis-/trans-1,3-oxathiolane nucleosides or their protected derivatives thereof, comprising: (i) treatment of the cis-/trans-1,3-oxathiolane nucleosides (or protected derivatives thereof) with a pyrimidine base (or it derivatives thereof) and an acid, (ii) adding a suitable acid to the obtained cis-/trans-mixture of isomers, (iii) selective crystallization of the desired cis-isomer salt from a solvent or combination of solvents, and (iv) treatment of the predominantly cis-isomer salt with a suitable base to offer the free 1,3-oxathiolane nucleosides, and thereafter optionally repeating steps (i) to (iv) inclusive.