A Selective Direct Aldol Reaction in Aqueous Media Catalyzed byZinc–Proline

Abstract

The Zn-proline complex is shown to catalyze the aldol reaction of acetone and a wide range of arenecarbaldehydes in aqueous media, accepting even deactivated arenecarbaldehydes such as methoxybenzaldehydes in good yields. Enantiomeric excesses of up to 56 % could be obtained with 5 mol-% of the catalyst at room temperature, and up to 66 %

Inorganic Polyphosphate Modulates TRPM8 Channels

“…If one of the substrate enantiomers is present even in small excess, the autocatalytic reaction can yield the corresponding product with up to 95% enantiomeric excess [312][313][314]. Although the mechanism of the Soai reaction remains unclear, Zn 2+ ions might be important -zinc-proline complexes were also shown to mediate stereoselective catalysis of aldole reactions in water [315]. At this point it is appropriate to mention that the Zn world settings could support all these mechanisms of stereoselectivity by providing (i) electrically charged surfaces with regular patterns of positive and negative charges, (ii) Zn 2+ ions that could build potentially catalytic complexes with diverse organic compounds, and (iii) UV light that would become polarized after passing through the ZnS crystals [316].…”

An overview of Zn-catalyzed enantioselective aldol type C–C bond formation

“…Darbre et al also reported that Zn-proline complex acts as an efficient catalyst for the direct aldol reaction of a wide variety of aryl and heteroaryl carbaldehydes and acetone. [40][41] The reactions were performed at room temperature in acetone-H 2 O (1:2) solvent system (Scheme 7). The catalytic abilities of other amino acid-zinc complexes were also investigated which revealed that Zn-lysine and Zn-arginine complexes could also act as catalysts for asymmetric aldol reactions.…”

Dynamic assembly of a zinc-templated bifunctional organocatalyst in the presence of water for the asymmetric aldol reaction

“…Several zinc-prolinate complexes that catalyze aldol reactions have been shown to be water-compatible. [7][8][9][10][11][20][21][22][23] However, in our zinc-pyridine ligands example presented herein, water is necessary to achieve higher stereoselectivity (Entries 5 and 7, Table 1). Furthermore, the amount of water must be carefully controlled to achieve optimal results.…”