Starting from ethyl 2-(3′,4′-di-O-acetyl-2′-deoxy-L-erythro-or -D-threo-pent-1′-enopyranosyl)thiazole-4-carboxylate (1, 2) the synthesis of variously functionalized pent-1′-enopyranosylthiazoles (4-11, 15-20) was carried out with different O-, C-, S-, N-, and H-nucleophiles in the presence of Lewis acids. The regio- and stereoselective reactions proceeded with the Lewis acid-mediated formation of a carbocation (I) and the stereochemistry of the incoming nucleophile was determined by the neighbouring 4′-acetoxy group. However, with trimethylsilyl cyanide a 2′,3′-unsaturated 1′-C-cyano derivative (26) was formed. The configuration and conformation of prepared unsaturated compounds was thoroughly studied and the presence of a conformational equilibrium 4H5 ⇌ 5H4 was deduced.
- conformational study
- unsaturated tiazofurin analogues
ASJC Scopus subject areas
- Drug Discovery
- Organic Chemistry