An asymmetric isomerization of β,γ-unsaturated butenolides with a newly developed betaine catalyst at a 0.2–2 mol% loading, an improvement upon available methods that use 0.5–2.0 mol% catalyst.
Synthesis of Levulinic Acids From Muconic Acids in Hot Water
作者:Céderic Ver Elst、Robby Vroemans、Mathias Bal、Sergey Sergeyev、Carl Mensch、Bert U. W. Maes
DOI:10.1002/anie.202309597
日期:2023.11.13
Hydrolysis of biorenewable muconic acids or their corresponding lactones in high temperature water allows the selective synthesis of levulinic acids. This enables direct access to novel substituted levulinic acidsfrom biomass, creating novel opportunities for industrial applications. 3-Propyllevulinic acid was used to synthesize a novel plasticizer which performed equally well as a commercial, petrochemical
Direct Enantioselective Brønsted Acid Catalyzed <i>N</i>-Acyliminium Cyclization Cascades of Tryptamines and Ketoacids
作者:Chloe A. Holloway、Michael E. Muratore、R. lan Storer、Darren J. Dixon
DOI:10.1021/ol101651t
日期:2010.11.5
A direct enantio- and diastereoselective N-acyliminium cyclization cascade through chiral phosphoric acid catalyzed condensation of tryptamines with gamma- and delta-ketoacid derivatives to provide architecturally complex heterocycles has been developed. The reaction is technically simple to perform, atom-efficient, and broad in scope. Employing 10 mol % of (R)-BINOL derived chiral phosphoric acids in refluxing toluene allowed the polycyclic product materials to be generated in good yields (53-99%) and moderate to high enantioselectivities (68-98% ee).