Rearrangement asymmetric thio-Claisen

Diastereoselective asymmetric thio-Claisen rearrangement has been carried out by the reaction of thioamides with allyllic bromide (Scheme 37).76... 

Diastereoselective asymmetric thio-Claisen rearrangement has been carried out by the reaction of thioamides with allyllic bromide (Scheme 37). Thioamide dianions (generated by the highly efficient reaction of A -benzyl thioamides with 2 equiv. of BuLi) take place alkylation, allylation and silylat-ion selectively at the carbon atom adjacent to the nitrogen atom of the thioamide dianions (Scheme 38). ... 

The first examples of an asymmetric thio-Claisen rearrangement induced by a cyclic chiral auxiUary were described by Reddy and Rajappa [127]. N-Nitrothioacetyl derivatives of (I)-aminoacid esters were used as substrates (Scheme 9.26). After allylation in the presence of DBU, the resulting S-allyl derivatives underwent facile thio-Claisen rearrangements upon heating at 50 °C but with modest chiral induction (up to 66% de). 

The first example of asymmetric thio-Claisen rearrangement based on axial chirality has been described by our group and involves atropisomeric thioanilides bearing an ortbo-tert-butyl group [132]. These axially chiral thioamides were subjected to LDA deprotonation followed by S-allylation with various allyl halides. 

Asymmetric induction can be caused by the presence of a sulfinyl group within the system [63]. In 1997, the group of Metzner reported the first examples of a thio-Claisen rearrangement stereocontrolled by a sulfinyl group... 

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