Highly enantioselective desymmetrization of anhydrides by carbon nucleophiles: reactions of Grignard reagents in the presence of (-)-sparteine was written by Shintani, Ryo;Fu, Gregory C.. And the article was included in Angewandte Chemie, International Edition in 2002.Reference of 10203-58-4 This article mentions the following:
Where other common chiral ligands failed, (-)-sparteine can be employed to form complexes with Grignard reagents. These chirally modified reagents desymmetrize a range of anhydrides with good enantioselectivity (up to 92% ee). Whereas (-)-sparteine is well known to form complexes with organolithium reagents and to induce excellent enantioselection in their reactions with electrophiles, (-)-sparteine-controlled asym. processes that involve Grignard reagents are rare. In the experiment, the researchers used many compounds, for example, Diethyl isobutylmalonate (cas: 10203-58-4Reference of 10203-58-4).
Diethyl isobutylmalonate (cas: 10203-58-4) belongs to esters. Carboxylic acid esters of low molecular weight are colourless, volatile liquids with pleasant odours, slightly soluble in water. Many esters have the potential for conformational isomerism, but they tend to adopt an s-cis (or Z) conformation rather than the s-trans (or E) alternative, due to a combination of hyperconjugation and dipole minimization effects. The preference for the Z conformation is influenced by the nature of the substituents and solvent, if present. Lactones with small rings are restricted to the s-trans (i.e. E) conformation due to their cyclic structure.Reference of 10203-58-4
Referemce:
Ester – Wikipedia,
Ester – an overview | ScienceDirect Topics