Our findings on the bifunctional squaramide‐catalyzed enantioselective conjugateaddition of β‐ketoamides to nitroolefins are disclosed. It appears that simple acyclic methylene β‐ketoamides, unlike the extensively studied β‐ketoesters, afford the products in excellent diastereoselectivities, and maintain high yields and enantioselectivities. Moreover, competition and kinetic studies were conducted
In a modification of the Wierenga-Skulnick β-ketoester synthesis, the dianions of malonic acid mono-amides were condensed with acid chlorides. Acidic workup led to decarboxylation and isolation of the corresponding β-keto amides in good-to-excellent yields. A similar procedure with cyanoacetic acid gave β-keto nitriles.
Synthesis of Enantiomerically Pure β-Hydroxy Ketones via β-Keto Weinreb Amides by a Condensation/Asymmetric-Hydrogenation/Acylation Sequence
作者:Julian Diehl、Reinhard Brückner
DOI:10.1002/ejoc.201601202
日期:2017.1.10
an ester/amide exchange, and the use of the resulting β-hydroxy amide for the acylation of an organometallic compound. We shortened this route by showing that β-keto Weinreb amides are hydrogenated with up to 99 % ee in the presence of [Me2NH2]+[RuCl(S)-BINAP]2(µ-Cl)3}– (0.5 mol-%) at room temp./5 bar. These Weinreb amides were prepared by seemingly obvious yet unprecedented condensations of lithiated