The asymmetric hydrogenation of α-halogenated ketones
with
iridium catalyst was developed, utilizing easily accessed cinchona-alkaloid-based
NNP ligands. Various α-chloroacetophenones, heterocyclic thienyl
and furanyl substrates, and even bromoketones were completely converted
to the desired chiral halohydrins by this protocol. Both (R)- and (S)-chiral halohydrins can be prepared
by changing the configurations of the chiral ligand NNP with up to
99.6% ee (enantiomeric excess) and 98.8% ee, respectively. Also, a
gram-scale experiment was carried out efficiently.
The
unprecedented metal-free synthesis of both N-unsubstituted
and N3-substituted quinazoline-2,4(1H,3H)-diones from o-aminobenzamides
and CO2 under atmospheric pressure at room temperature
is developed. This protocol easily allows for variations of functional
groups (including alkyl, aryl, and heterocycle groups) at the N3-position to accommodate the construction of many important
drugs and bioactive compounds. The reaction features eco-friendliness,
substrate scope tolerance, and versatility and can be implemented
even at the gram scale.
Iridium complexes generated in situ from [Ir(COD)Cl]2 and cinchona alkaloid derived NNP Ligand has been developed for the asymmetric transfer hydrogenation of aromatic ketones. In this study, 30 aromatic ketones...
A concise synthesis of cinchona-alkaloid-derived NN ligands bearing alkyl substituents on chiral nitrogen atoms was described. Iridium catalysts containing new chiral NN ligands and achiral phosphines were effective for the asymmetric hydrogenation of heteroaromatic ketones, which afforded corresponding alcohols in up to 99.9% ee. The same protocol was applicable to the asymmetric hydrogenation of α-chloroheteroaryl ketones. Most importantly, the gram-scale asymmetric hydrogenation of 2-acetylthiophene and 2-acetylfuran proceeded smoothly even under 1 MPa of H 2 .Article pubs.acs.org/joc
A range of cinchona alkaloid-derived NN ligands bearing N-H moieties were employed for the asymmetric hydrogenation of ketones. By substituting the N-H moieties of the NN ligand, we demonstrated that...
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