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.
An
enantioselective hydrogenation of 5-alkylidene-2,4-diketoimidazolidines
(hydantoins) and 3-alkylidene-2,5-ketopiperazines catalyzed by the
Rh/f-spiroPhos complex under mild conditions has
been developed, which provides an efficient approach to the highly
enantioselective synthesis of chiral hydantoins and 2,5-ketopiperazine
derivatives with high enantioselectivities up to 99.9% ee.
A highly efficient asymmetric hydrogenation of a series of γ-keto acid derivatives, including γ-keto acids, esters, and amides, using a Ni-(R,R)-QuinoxP* complex as the catalyst has been developed to afford chiral γ-hydroxy acid derivatives with excellent enantioselectivities, up to 99.9% ee. This method provides not only an economical one-pot approach for the synthesis of chiral γ-lactones but also access to (S)-norfluoxetine, an inhibitor of neural serotonin reuptake and an essential intermediate for pharmaceutical synthesis. Letter pubs.acs.org/OrgLett
A highly enantioselective rhodium-catalyzed reductive dearomatization of 7-substituted pyrazolo[1,5-a]pyrimidines has been first realized by two strategies to afford chiral 4,5,6,7-tetrahydropyrazolo[1,5-a]pyrimidines with excellent enantioselectivities of up to 98% ee. This method...
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