- Asymmetric hydrogenation of maleic acid diesters and anhydrides
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Asymmetric hydrogenation of maleic and fumaric acid derivatives with iridium catalysts based on N,P ligands provides an efficient route to chiral enantioenriched succinates. A new catalyst derived from a 2,6-difluorophenyl- substituted pyridine-phosphinite ligand was developed and enables the conversion of a wide range of 2-alkyl and 2-arylmaleic acid diesters into the corresponding succinates in high enantiomeric purity. Mixtures of cis/trans substrates can be hydrogenated in an enantioconvergent fashion with high enantioselectivity, and further enhances the scope of this transformation. The products are valuable chiral building blocks with a structural motif found in many bioactive compounds, such as metalloproteinase inhibitors. An attractive enantioselective route to 2-alkyl- and 2-aryl-substituted succinic acid derivatives is opened up by the asymmetric hydrogenation of maleic and fumaric acid derivatives, using the new catalyst [Ir(cod)L]BArF, derived from a 2,6-difluorophenyl-substituted pyridine-phosphinite ligand. The products are valuable chiral building blocks having a structural motif found in many bioactive compounds. cod=1,5-cyclooctadiene.
- Bernasconi, Maurizio,Mueller, Marc-Andre,Pfaltz, Andreas
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supporting information
p. 5385 - 5388
(2014/06/09)
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- Kinetic and mechanistic study of the H-transfer reduction of dimethyl itaconate by a Rh/TPPTS catalyst under biphasic conditions: Evidence for a rhodametallacycle intermediate
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The H-transfer reduction of dimethyl itaconate under biphasic catalysis using sodium formate/water as the hydrogen source with a Rh/TPPTS complex was studied. Labelling experiments reveal that the reduction proceeds through a 1,3-hydrogen addition. Kinetic studies allow us to propose a catalytic cycle going through a rhodametallacyclobutane intermediate with a rate-determining step involving sodium formate. A formal kinetic rate law was then derived from this mechanism which accounts for the results. This work evidences the switch between the mechanism of diacid reduction and that of the corresponding esters.
- Tanchoux, Nathalie,De Bellefon, Claude
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p. 1495 - 1502
(2007/10/03)
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