Synthesis of enantiopure trans-2,5-disubstituted trifluoromethylpyrrolidines and (2S,5R)-5-trifluoromethylproline.

Enantiopure trans-2,5-disubstituted trifluoromethylpyrrolidines were prepared on a several gram scale starting from a readily available chiral fluorinated oxazolidine (Fox). A pure oxazolopyrrolidine intermediate could be obtained after an efficient separation by selective diastereomer destruction. The addition of various Grignard reagents on this oxazolopyrrolidine provided disubstituted pyrrolidines with moderate to complete trans diastereoselectivity. The highly valuable compound (2S,5R)-5-trifluoromethylproline could be synthesized from the same oxazolopyrrolidine intermediate via a Strecker-type reaction.

Straightforward glycosylation of alcohols and amino acids mediated by ionic liquid.

Green glycosylation of functionalized alcohols and α-amino acids, using an ionic liquid as a recyclable solvent, was performed in one step directly from the unprotected monosaccharide under scandium triflate or ferric chloride catalysis. Pure α- and ß-glycosides could be obtained after specific enzymatic hydrolysis.