- Asymmetric Hydrogenation of Cationic Intermediates for the Synthesis of Chiral N,O-Acetals
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For over half a century, transition-metal-catalyzed homogeneous hydrogenation has been mainly focused on neutral and readily prepared unsaturated substrates. Although the addition of molecular hydrogen to C=C, C=N, and C=O bonds represents a well-studied paradigm, the asymmetric hydrogenation of cationic species remains an underdeveloped area. In this study, we were seeking a breakthrough in asymmetric hydrogenation, with cationic intermediates as targets, and thereby anticipating applying this powerful tool to the construction of challenging chiral molecules. Under acidic conditions, both N- or O-acetylsalicylamides underwent cyclization to generate cationic intermediates, which were subsequently reduced by an iridium or rhodium hydride complex. The resulting N,O-acetals were synthesized with remarkably high enantioselectivity. This catalytic strategy exhibited high efficiency (turnover number of up to 4400) and high chemoselectivity. Mechanistic studies supported the hypothesis that a cationic intermediate was formed in situ and hydrogenated afterwards. A catalytic cycle has been proposed with hydride transfer from the iridium complex to the cationic sp2 carbon atom being the rate-determining step. A steric map of the catalyst has been created to illustrate the chiral environment, and a quantitative structure–selectivity relationship analysis showed how enantiomeric induction was achieved in this chemical transformation.
- Sun, Yongjie,Zhao, Qingyang,Wang, Heng,Yang, Tilong,Wen, Jialin,Zhang, Xumu
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supporting information
p. 11470 - 11477
(2020/08/10)
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- Substituted Dihydroimidazoles and their Use in the Treatment of Tumors
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The invention relates to dihydroimidazoles of formula rac-(I), wherein the radicals and symbols are as defined herein; their use as inhibitors of the interaction of the MDM2 protein with a p53-like peptide, new pharmaceutical formulations comprising said compounds, said compounds for use in the therapeutic treatment of warm-blooded animals, especially humans, their use in the treatment of proliferative diseases or for the manufacture of pharmaceutical formulations useful in the treatment of proliferative diseases that respond to modulation of the interaction of the MDM2 protein with a p53-like peptide, a pharmaceutical formulation e.g. useful in the treatment of proliferative diseases that respond to modulation of the interaction of the MDM2 protein with a p53-like peptide comprising said compound, methods of treatment comprising administration of said compounds to a warm-blooded animal, and/or processes for the manufacture of said compounds.
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Page/Page column 12
(2010/04/23)
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