An unprecedented Ir-catalyzed asymmetric cascade umpolung allylation/2-aza-Cope rearrangement of trifluoroethylisatin ketimines has been realized. The current method provides a facile access to biologically important αtrifluoromethyl-containing homoallylic amines in high yields with excellent enantioselectivity. Notably, umpolung reactivity of trifluoroethylisatin ketimine was discovered for the first time. Mechanism studies revealed the key intermediates in the initial umpolung allylation and the stereospecific chirality transfer in the subsequent 2-aza-Cope rearrangement. Letter pubs.acs.org/OrgLett
In this study, we developed an efficient Ir-catalyzed cascade umpolung allylation/2-aza-Cope rearrangement for the preparation of a variety of quaternary trifluoromethyl α-ε-amino acids in high yields with excellent enantioselectivities.
The
first example of highly efficient kinetic resolution of exo-3-oxodicyclopentadienes and endo-3-oxodicyclopentadiene
has been developed by means of Cu(I)-catalyzed asymmetric 1,3-dipolar
cycloaddition of azomethine ylide. Compared with the existing methodologies
for those synthetically important optically active convex molecules,
the current protocol provides an alternative but more practical approach
from the readily available racemic starting materials, which is free
from the repetitive reduction/oxidation steps in the enzymatic resolution
or the indispensable stoichiometric amount of chirality-induction
reagents.
Facile access to quaternary α-trifluoromethyl α-amino acids has been developed. This sequential reaction involves an Ir-catalyzed asymmetric allylation of α-trifluoromethyl aldimine esters followed by an unprecedented kinetic resolution.
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