Dynamic Kinetic Resolution Of β-Keto Sulfones Via Direct Aldol Reaction--Synthesis Of Chiral β-Hydroxysulfones

Synthesis of (R)-5-benzhydryl-2-phenyl-5,6-dihydrooxazolo[2,3-c] [1,2,4] triazol-2-ium chlorideA novel chiral NHC organocatalyst aimed to catalyze asymmetric benzoin condensation was designed and its precursor (R)-5-benzhydryl-2-phenyl-5,6- dihydrooxazolo[2,3-c][1,2,4] triazol-2-ium chloride has been prepared via a seven-step synthesis.Dynamic Kinetic Resolution ofβ-Keto Sulfones via Direct Aldol ReactionUnder the catalysis of L-Proline, 3-(sulphonyl)ketoesters and acetone underwent asymmetric Aldol reaction, forming multifunctional chiralβ-hydroxysulfones containing two adjacent chiral centers via dynamic kinetic resolution in good yields with excellent enantioselectivities (up to 98% ee) and diastereoselectivity (> 99:1).