Iridium-Catalyzed Enantioselective Hydrogenation of Imines in Supercritical Carbon Dioxide

Autor:	Sabine Kainz, Walter Leitner, Andreas Pfaltz, Axel Brinkmann
Rok vydání:	1999
Předmět:	Trifluoromethyl Supercritical carbon dioxide Chemistry Enantioselective synthesis chemistry.chemical_element General Chemistry Biochemistry Medicinal chemistry Asymmetric induction Catalysis chemistry.chemical_compound Colloid and Surface Chemistry Aniline Organic chemistry Iridium Solubility
Zdroj:	Journal of the American Chemical Society. 121:6421-6429
ISSN:	1520-5126 0002-7863
DOI:	10.1021/ja984309i
Popis:	Supercritical carbon dioxide (scCO2) was shown to be a reaction medium with unique properties for highly efficient iridium-catalyzed enantioselective hydrogenation of prochiral imines. Cationic iridium(I) complexes with chiral phosphinodihydrooxazoles, modified with perfluoroalkyl groups in the ligand or in the anion, were synthesized and tested in the hydrogenation of N-(1-phenylethylidene)aniline. Both the side chains and the lipophilic anions increased the solubility, but the choice of the anion also had a dramatic effect on the enantioselectivity with tetrakis-3,5-bis(trifluoromethyl)phenylborate (BARF) leading to the highest asymmetric induction. (R)-N-phenyl-1-phenylethylamine was formed quantitativley within 1 h in scCO2 [d(CO2) = 0.75 g mL-1] at 40 °C and a H2 pressure of 30 bar with enantiomeric excesses of up to 81% using 0.078 mol % catalyst. The use of scCO2 instead of conventional solvents such as CH2Cl2 allowed the catalyst loading to be lowered significantly owing to a change in the rate pr...
Databáze:	OpenAIRE
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