A highly efficient enantioselective hydrogenation of α,β-unsaturated nitriles catalyzed by Rh-(R,R)-f-spiroPhos complex has been developed. With Rh-(R,R)-f-spiroPhos catalyst and under mild conditions, a wide range of α,β-unsaturated nitriles including the (E)- and (Z)-isomers of 3-alkyl-3-aryl, 3,3-diaryl, and 3,3-dialkyl α,β-unsaturated nitriles were hydrogenated to the corresponding chiral nitriles with excellent enantioselectivities (up to 99.9% ee) and high turnover numbers (TON up to 10,000).
Chiral cyclic amines can be prepared via intramolecular reductive amination of N-Boc-protected amino ketones in a one-pot process. With the complex of iridium and f-spiroPhos as the catalyst, a range of N-Boc-protected amino ketones are smoothly transformed into chiral cyclic free amines in high yields and excellent enantioselectivities (up to 97% ee). Moreover, this method can also be successfully applied to the synthesis of a κ-opioid receptor selective antagonist, (S)-1.
A highly efficient
and enantioselective Rh-(R,R)-f-spiroPhos
complex catalyzed hydrogenation of a series
of unsaturated sulfones has been developed. With Rh-(R,R)-f-spiroPhos catalyst under mild conditions,
not only the asymmetric hydrogenation of both the 3,3-diaryl and exocyclic
α,β-unsaturated sulfones was first realized with up to
99.9% ee but also 3-alkyl-3-aryl and benzo[b]thiophene-1,1-dioxides
were successfully hydrogenated to the corresponding chiral sulfones
with excellent enantioselectivities (up to 99.4% ee) regardless of
the steric hindrance, electronic property, and geometry of the substrates.
Moreover, this reaction offers a route to (S)-(+)-ar-turmerone as a spice flavor, which is an important synthetic
intermediate of pharmaceuticals.
The first highly efficient Ir-catalyzed enantioselective hydrogenation of β-acylamino nitroolefins is reported. This reaction provides straightforward access to chiral β-amino nitroalkanes in high yields and excellent enantioselectivities (up to >99.9% ee) catalyzed by an Ir-(R,R)-f-spiroPhos complex.
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