Catalyst Repurposing Sequential Catalysis by Harnessing Regenerated Prolinamide Organocatalysts as Transfer Hydrogenation Ligands
作者:Frederic Bourgeois、Jonathan A. Medlock、Werner Bonrath、Christof Sparr
DOI:10.1021/acs.orglett.9b04033
日期:2020.1.3
A catalyst repurposing strategy based on a sequential aldol addition and transferhydrogenation giving access to enantiomerically enriched α-hydroxy-γ-butyrolactones is described. The combination of a stereoselective, organocatalytic step, followed by an efficient catalytic aldehydereduction induces an ensuing lactonization to provide enantioenriched butyrolactones from readily available starting
Peptide-Catalyzed Highly Asymmetric Cross-Aldol Reaction of Aldehydes to Biomimetically Synthesize 1,4-Dicarbonyls
作者:Zhi-Hong Du、Bao-Xiu Tao、Meng Yuan、Wen-Juan Qin、Yan-Li Xu、Pei Wang、Chao-Shan Da
DOI:10.1021/acs.orglett.0c01407
日期:2020.6.5
beta-Turn tetrapeptides were demonstrated to catalyze asymmetric aldol reaction of alpha-branched aldehydes and acarbonyl aldehydes, i.e. glyoxylates and alpha-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 BS, was readily accessed in a practical, efficient, and environmentally benign process from inexpensive starting materials.