First Examples of a Claisen Rearrangement Stereocontrolled by a Sulfinyl Group: Synthesis of Novel α‐Sulfinyl Dithioesters

Diastereomeric excesses up to 98% are a characteristic of the Claisen rearrangement of ketene dithioacetals 1, which contain a chiral sulfinyl group, to afford γ-unsaturated α-sulfinyl dithioesters 2. This reaction is the first example of a [3,3] rearrangement whose stereochemical course is controlled by a sulfinyl group. Owing to the mild thermal conditions (room temperature) undesired elimination of sulfenic acid was not observed.