In the catalysis of S(N)2 fluorination reactions, the ionic liquid anion plays a key role as a Lewis base by binding to the counterion Cs(+) and thereby reducing the retarding Coulombic influence of Cs(+) on the nucleophile F(-). The reaction rates also depend critically on the structures of ionic liquid cation, for example, n-butyl imidazolium gives no S(N)2 products, whereas n-butylmethyl imidazolium works well. The origin of the observed phenomenal synergetic effects by the ionic liquid [mim-(t)OH][OMs], in which t-butanol is bonded covalently to the cation [mim], is that the t-butanol moiety binds to the leaving group of the substrate, moderating the retarding interactions between the acidic hydrogen and F(-). This work is a significant step toward designing and engineering solvents for promoting specific chemical reactions.

Highly enantioselective biomimetic Michael addition reactions of malonic acid half thioesters (MAHTs) to a variety of nitroolefins, affording the optically active g-amino acid precursors, were developed by employing the Cinchona-based squar-A C H T U N G T R E N N U N G amides (up to > 99% ee). Remarkably, this biomimetic process is enantioconvergent, a highly desirable feature of a catalytic asymmetric reaction, whereby E/Z-isomers of the nitroolefins afford the same product enantiomer. The synthetic utility of this organocatalytic protocol was also demonstrated in the formal synthesis of pharmaceutically important gamino acids such as baclofen. Moreover, a quantum chemical analysis of the catalyst-substrate complexes is shown to give a detailed and instrumental insight into the origin of the observed catalytic activity.

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The amide (ALK) efficiently promotes the asymmetric coupling of nitroolefins with the thioester (II) giving adducts of type (III)/(VII) with high enantioselectivity.