Asymmetric synthesis of 2,4,5-trisubstituted Δ2-thiazolines.

Δ(2)-Thiazolines are interesting heterocycles that display a wide variety of biological characteristics. They are also common in chiral ligands used for asymmetric syntheses and as synthetic intermediates. Herein, we present asymmetric routes to 2,4,5-trisubstituted Δ(2)-thiazolines. These Δ(2)-thiazolines were synthesized from readily accessible/commercially available α,β-unsaturated methyl esters through a Sharpless asymmetric dihydroxylation and an O→N acyl migration reaction as key steps. The final products were obtained in good yields with up to 97 % enantiomeric excess.