Asymmetric Michael addition between kojic acid derivatives and unsaturated ketoesters promoted by C2-symmetric organocatalysts. Issue 48 (9th November 2018) - Kostenko, Alexey A.
Abstract : An efficient C 2 -symmetric bifunctional tertiary amine–squaramide organocatalyst for the asymmetric Michael addition/hemiketalization domino reaction of kojic acid derivatives with β, γ-unsaturated α-ketoesters has been designed. Abstract : An efficient sterically hindered C 2 -symmetric bifunctional tertiary amine–squaramide organocatalyst for the asymmetric Michael addition/hemiketalization domino reaction of kojic acid derivatives with β, γ-unsaturated α-ketoesters has been designed. Pharmacology-relevant functionalized 2, 3, 4, 8-tetrahydropyrano[3, 2- b ]pyran derivatives were produced over the catalyst in as low as 1 mol% with up to 99% yield and 99% ee. The procedure is at least 30-fold scalable and the catalyst is readily reusable in the catalytic reaction via acid–base extraction. Acylation of the products with ( S )- or rac -ibuprofen and with undec-10-enoic acid afforded the corresponding chiral esters containing two privileged pharmacophoric motifs.