4 research outputs found
Ni-Catalyzed Asymmetric Hydrogenation of α‑Substituted α,β-Unsaturated Phosphine Oxides/Phosphonates/Phosphoric Acids
Efficient Ni/(S,S)-Ph-BPE-catalyzed
asymmetric hydrogenation of α-substituted α,β-unsaturated
phosphine oxides/phosphonates/phosphoric acids has been successfully
developed, and a wide range of chiral α-substituted phosphines
hydrogenation products were obtained in generally high yields with
excellent enantioselective control (92%–99% yields, 84%−>99% ee). This method features a cheap
transition metal nickel catalytic system, high functional group tolerance,
wide substrate scope generality, and excellent enantioselectivity.
A plausible catalytic cycle was proposed for this asymmetric hydrogenation
according to the results of deuterium-labeling experiments
Selective Rhodium-Catalyzed Hydroformylation of Alkynes to α,β-Unsaturated Aldehydes with a Tetraphosphoramidite Ligand
A tetraphosphoramidite
ligand was successfully applied to a Rh-catalyzed
hydroformylation of various symmetrical and unsymmetrical alkynes
to afford corresponding α,β-unsaturated aldehyde products
in good to excellent yields (up to 97% yield). Excellent chemo- and
regioselectivities and high activities (up to 20 000 TON) were
achieved. The corresponding α,β-unsaturated aldehyde products
can be transformed into many useful and important organic molecules,
such as indenamine derivatives and lukianol pyrroles. This great performance
makes the hydroformylation of alkynes highly practical with great
potential
Highly Enantioselective Synthesis of Chiral Succinimides via Rh/Bisphosphine-Thiourea-Catalyzed Asymmetric Hydrogenation
We have successfully developed a
highly enantioselective hydrogenation
of various 3-aryl and 3-methyl maleinimides to access enantiomerically
pure 3-substituted succinimides catalyzed by Rh/bisphosphine-thiourea
(ZhaoPhos). This efficient catalytic system furnished the desired
3-substituted succinimide products with high yields and enantioselectivities
(up to 99% yield, full conversions, almost all 3-aryl succinimide
products up to 99% ee, and 3-methyl succinimide with 83% ee). Our
catalytic system has a strong substrate tolerance and generality.
Whether the N-substituted group of maleinimides is H or other protecting
groups, the maleinimides were hydrogenated well (up to >99% ee,
99%
yield). Moreover, the hydrogenation succinimide products can be readily
utilized for the construction of biologically active molecules, such
as chiral amides and pyrrolidines
Highly Enantioselective Asymmetric Hydrogenation of Carboxy-Directed α,α-Disubstituted Terminal Olefins via the Ion Pair Noncovalent Interaction
The <i>t</i>-Bu-Wudaphos was successfully applied into
Rh-catalyzed asymmetric hydrogenation of α,α-disubstituted
terminal olefins bearing a carboxy-directed group with excellent reactivities
and enantioselectivities via the ion pair noncovalent interaction
(up to >99% conversion, 98% yield, 98% ee) under mild reaction
conditions
without base. In addition, control experiments were conducted, and
the results demonstrated that the ion pair noncovalent interaction
between ligand and substrate played an important role in achieving
an outstanding performance in this asymmetric hydrogenation