No abstract

β-Turn tetrapeptides were demonstrated to catalyze asymmetric aldol reaction of α-branched aldehydes and α-carbonyl aldehydes, i.e. glyoxylates and α-ketoaldehydes, to biomimetically synthesize acyclic all-carbon quaternary center-bearing 1,4-dicarbonyls in high yield and excellent enantioselectivity under mild conditions. The spatially restricted environment of the tetrapeptide warrants high enantioselectivity and yield with broad substrates. Using this protocol, (R)-pantolactone, the key intermediate of vitamin B5, was readily accessed in a practical, efficient, and environmentally benign process from inexpensive starting materials.

The highly asymmetric Michael addition reaction between maleimides and aliphatic aldehydes catalyzed by low-loading β-turn tetrapeptides with excellent yield and enantioselectivity at room temperature was reported. α-Branched and α-unbranched aldehydes...

This work demonstrates that a tert-leucine-derived 2-phenolic anilide is the efficient organocatalyst to catalyze the asymmetric cross-aldol reaction of glyoxylate and alkyl aldehydes in high yield and enantioselectivity at room temperature. As compared to the reported simple primary amino acids, the 2-phenolic anilide can produce two hydrogen bonds from its phenolic hydroxy and amide groups with aldehyde moiety of ethyl glyoxylate, greatly enhancing the electrophilicity of ethyl glyoxylate and effectively increasing the asymmetric induction of the aldol reaction. Additionally, the large side group-bearing tert-leucine is also essential to high enantioselectivity. The reaction was successfully performed on 50 mmol scale with no decrease in the yield and enantioselectivity, showing potential for the chemical production of the pharmaceutical intermediate (R)-pantolactone with high yield and enantiopurity in an eco-friendly method.