Design of sulfides with a locked conformation as promoters of catalytic and asymmetric sulfonium ylide epoxidation.
[reaction: see text] A new generation of 2,5-dimethylthiolanes with a locked conformation was developed to promote the asymmetric addition of chiral sulfonium ylides to aldehydes. The novel chiral sulfur derivative 4 succeeded the synthesis of trans-stilbene oxide derivatives with enantiomeric ratios ranging from 95:5 to 98:2. This user-friendly organocatalytic process proved to be efficient with 20-10% of sulfide 4 in 1 or 2 days of reaction. An insight into the ylide intermediate conformation is given on the basis of a computational ab initio study.
Davoust
Marion
M
Laboratoire de Chimie Moléculaire et Thio-organique (UMR CNRS 6507), ENSICaen-Université de Caen, 6 Boulevard du Maréchal Juin, 14050 Caen, France.
Brière
Jean-François
JF
Jaffrès
Paul-Alain
PA
Metzner
Patrick
P