200720-85-0Relevant academic research and scientific papers
Diastereoselective rhodium(II)-catalyzed sulfonium ylide formation-[2,3]-sigmatropic rearrangement reaction of chiral non-racemic allylic sulfides
Wee, Andrew G. H.,Shi, Qing,Wang, Zhongyi,Hatton, Kimberly
, p. 897 - 909 (2007/10/03)
The tandem sulfonium ylide formation-[2,3]-sigmatropic rearrangement reaction of chiral non-racemic secondary allylic sulfides, (E)-9 and (Z)-10, is found to proceed with high diastereocontrol. The C-5 stereocenter bearing the sulfide group is essential for high diastereoselectivity in the reaction. Transition state conformers are proposed to explain the high diastereoselectivity in the formation of the diastereomeric products, 18a and 18b. The method is applied to the synthesis of (R)-4-(4-chlorophenyl)-2-butyrolactone. Modest enantioselectivity (63% ee) was achieved and this is attributed to partial racemization during the formation of the secondary allylic sulfide 22.
Enantioselective synthesis of β-substituted butyric acid derivatives via orthoester Claisen rearrangement of enzymatically resolved allylic alcohols: Application to the synthesis of (R)-(-)-baclofen
Brenna, Elisabetta,Caraccia, Nicola,Fuganti, Claudio,Fuganti, Daniela,Grasselli, Piero
, p. 3801 - 3805 (2007/10/03)
A three step synthesis of (R)-(-)-baclofen is described. The key step is the orthoester Claisen rearrangement of enantiopure allylic alcohol (S,E)-(-)-1a, affording γ,δ-unsaturated ester (S,E)-(+)-6 with high stereoselectivity. This latter derivative is converted into (R)-(-)-baclofen through a high yield one-pot reaction.
