Direct catalytic asymmetric Mannich reactions of malonates and β-keto esters was written by Marigo, Mauro;Kjaersgaard, Anne;Juhl, Karsten;Gathergood, Nicholas;Jorgensen, Karl Anker. And the article was included in Chemistry – A European Journal in 2003.Computed Properties of C11H20O4 This article mentions the following:
The first catalytic asym. direct Mannich reaction of malonates and β-keto esters has been developed. Malonates react with an activated N-tosyl-α-imino ester catalyzed by chiral tert-butyl-bisoxazoline/Cu(OTf)2 to give the Mannich adducts in high yields and with up to 96% ee. These reactions create a chiral quaternary carbon center and it is demonstrated that this new direct Mannich reactions provides for example a new synthetic procedure for the formation of optically active β-carboxylic ester α-amino acid derivatives A series of different β-keto esters with various ester substituents has been screened as substrates for the catalytic asym. direct Mannich reaction and it was found that the best results in terms of yield, diastereo- and enantioselectivity were obtained when tert-Bu esters of β-keto esters were used as the substrate. The reaction of different β-keto tert-Bu esters with the N-tosyl-α-imino ester gave the Mannich adducts in high yields, diastereo- and enantioselectivities (up to 95% ee) in the presence of chiral tert-butyl-bisoxazoline/Cu(OTf)2 as the catalyst. To expand the synthetic utility of this direct Mannich reaction, a diastereoselective decarboxylation reaction was developed for the Mannich adducts leading to a new synthetic approach to attractive optically active β-keto α-amino acid derivatives Based on the stereochem. outcome of the reactions, various approaches of the N-tosyl-α-imino ester to the chiral bisoxazoline/CuII-substrate intermediate are discussed. In the experiment, the researchers used many compounds, for example, Diethyl isobutylmalonate (cas: 10203-58-4Computed Properties of C11H20O4).
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. Esters contain a carbonyl center, which gives rise to 120° C–C–O and O–C–O angles. Unlike amides, esters are structurally flexible functional groups because rotation about the C–O–C bonds has a low barrier. Their flexibility and low polarity is manifested in their physical properties; they tend to be less rigid (lower melting point) and more volatile (lower boiling point) than the corresponding amides. Computed Properties of C11H20O4
Referemce:
Ester – Wikipedia,
Ester – an overview | ScienceDirect Topics