3 research outputs found
Organocatalytic Sequential α-Amination/Corey–Chaykovsky Reaction of Aldehydes: A High Yield Synthesis of 4-Hydroxypyrazolidine Derivatives
A tandem reaction of <i>in situ</i> generated α-amino aldehydes with dimethyloxosulfonium methylide under Corey–Chaykovsky reaction conditions proceeds efficiently to give 4-hydroxypyrazolidine derivatives in high yields with excellent enantio- and diastereoselectivities. This organocatalytic sequential method provides for the efficient synthesis of <i>anti-</i>1,2-aminoalcohols, structural subunits present in several bioactive molecules as well
Proline-Catalyzed Sequential <i>syn</i>-Mannich and [4 + 1]-Annulation Cascade Reactions To Form Densely Functionalized Pyrrolidines
A highly
efficient one-pot [4 + 1]-annulation process for the asymmetric synthesis
of densely functionalized pyrrolidine derivatives is described. The
in situ generated <i>syn</i>-Mannich adduct obtained via
proline catalysis acts as a four-atom component, and Corey’s
sulfur ylide or ethyl bromoacetate acts as a one-atom carbon source
to construct pyrrolidine units in a highly enantio- and diastereoselective
manner
Fluoride Anions in Self-Assembled Chiral Cage for the Enantioselective Protonation of Silyl Enol Ethers
The potential of Song’s
chiral oligoethylene glycols (oligoEGs) as catalysts was explored
in the enantioselective protonation of trimethylsilyl enol ethers
in combination with alkali metal fluoride (KF and CsF) and in the
presence of a proton source. Highly enantioselective protonations
of various silyl enol ethers of α-substituted tetralones were
achieved, producing chiral α-substituted tetralones in full
conversion and with up to 99% ee. The established protocol was successfully
extended to the synthesis of biologically relevant chiral α-substituted
chromanone and thiochromanone derivatives