Oxazolidines, isomerization synthesis

Reaction of the carbohydrate-based cyclic sulfites with NaSCN was used for the synthesis of f -l, 2-liised oxazolidine-2-thiones (Table 4) <1995TL5347>. Seleno and oxo derivatives were obtained with KSeCN or NaOCN, respectively <2000MI397>. The stereochemistry of products can be explained by the intermediate isomerization of /3-thiocyanates into cr-isothiocyanates (Scheme 10) <1995TL5347, 2000MI397>. 

A base-induced ring-opening imine isomerization/diastereoselective organometallic addition sequence on 4-substituted-2-perfluoroalkyl-l,3-oxazolidines 205 was developed for the asymmetric synthesis of perfluoroalkyl amino alcohols 207 via intermediates 206. Chiral compounds were obtained in good yields and high diastereoselectivity <04OL641>. 

The ribofuranosyl-oxazolidine thione(6) has been used as a source of a-ribofuranosyl imidazole derivatives leading to purine and 2-azapurine a-nucleosides. D-Arabinose or D-ribose reacts with cyanamide to yield isomeric 2-amino-l,2-oxazolines (7), which are useful intermediates for nucleoside synthesis.The P-N ylide (8) has been used to prepare tetrazole nucleosides by conversion to the diimide (9) with isocyanate and subsequent azide cyclo addition.Conversely, glycosyl azides undergo cyclo-... 

---