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.
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.
Described here is the first organocatalytic asymmetric N−H insertion reaction of α-carbonyl sulfoxonium ylides. Without a metal catalyst, this reaction represents an attractive complement to the well-established carbene insertion reactions....
Ir-catalyzed
asymmetric hydrogenation of quinolines was developed,
and both enantiomers of chiral tetrahydroquinoline derivatives could
be easily obtained, respectively, in high yields with good enantioselectivities
through the adjustment of reaction solvents (toluene/dioxane: up to
99% yield, 98% ee (R), TON = 680; EtOH: up to 99%
yield, 94% ee (S), TON = 1680). It provided an efficient
and simple synthetic strategy for the enantiodivergent synthesis of
chiral tetrahydroquinolines, and gram-scale asymmetric hydrogenation
proceeded well with low-catalyst loading in these two reaction systems.
A series of deuterium-labeling experiments, control experiments, and 1H NMR and electrospray ionization-mass spectrometry experiments
have been conducted, and a reasonable and possible reaction process
was revealed on the basis of these useful observations.
Nickel-catalyzed stereospecific syn-selective asymmetric hydrogenation of challenging tetrasubstituted fluorinated enamides has been achieved. This protocol provides an efficient access to chiral α-fluoro-β-amino esters.
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