650601-10-8Relevant articles and documents
Iridium and Rhodium Complexes Containing Enantiopure Primary Amine-Tethered N-Heterocyclic Carbenes: Synthesis, Characterization, Reactivity, and Catalytic Asymmetric Hydrogenation of Ketones
Wan, Kai Y.,Roelfes, Florian,Lough, Alan J.,Hahn, F. Ekkehardt,Morris, Robert H.
, p. 491 - 504 (2018)
The imidazolium salt [(S,S)-tBuNC3H3NCHPhCHPhNH2]PF6, (S,S)-11·HPF6 is a precursor to the enantiopure "Kaibene" ligand, tBu-Kaibene, (S,S)-11 featuring a tert-butyl group on the N-heterocyclic carbene (NHC) ring-nitrogen atoms. It has been prepared in high yield and purity by refluxing a chiral cyclic sulfamidate with 1-tert-butylimidazole. Similarly (S,S)-12·HPF6 with a mesityl group at the imidazolium ring-nitrogen atom has been prepared in the same fashion and serves as a source of Mes-Kaibene, (S,S)-12. These bidentate Kaibene ligands feature an NHC and a primary amine separated by a chiral linker. Salts (S,S)-11·HPF6 or (S,S)-12·HPF6 react with base and AgI or CuI to give a total of four M(Kaibene)2I compounds (M = Ag or Cu). At 22 °C, the amine-functionalized imidazolium cations undergo oxidative addition to iridium(I) in [IrCl(cod)]2 (cod = 1,5-cyclooctadiene) to generate iridium(III) hydride R-Kaibene compounds [IrHCl(cod)((S,S)-11)](PF6) (17) and [IrHCl(cod)((S,S)-12)](PF6) (18), respectively, each as a mixture of six configurational isomers. In contrast, the salt (S,S)-11·HPF6 reacts with [Ir(OtBu)(cod)]2 to produce a bimetallic iridium compound with (S,S)-11 as the bridging ligand. This compound contains interesting NH···Cl and NH···Ir noncovalent intramolecular interactions. Salt (S,S)-12·HPF6 reacts with silver oxide to yield [Ag2((S,S)-12)2](PF6)2 (20). Reagent 20 serves as an efficient transmetalation reagent to deliver to each rhodium in [RhCl(cod)]2 1 equiv of (S,S)-12 as a bidentate ligand to give [Rh(cod)((S,S)-12)](PF6). In the reaction between [IrCl(cod)]2 and 20, (S,S)-12 ends up coordinated in an iridium(III) hydride complex (22) as a tridentate ligand via the NHC, NH2, and a cyclometalated phenyl group. The two iridium hydride compounds, 18 and 22, are catalysts for the hydrogenation of a range of ketones (turnover number up to 499, turnover frequency up to 249 h-1, with er (enantiomeric ratio) up to 35:65 R:S).
Asymmetric preparation of antifungal 1-(4′-chlorophenyl)-1- cyclopropyl methanol and 1-(4′-chlorophenyl)-2-phenylethanol. Study of the detoxification mechanism by Botrytis cinerea
Pinedo-Rivilla, Cristina,Bustillo, Antonio J.,Hernandez-Galan, Rosario,Aleu, Josefina,Collado, Isidro G.
experimental part, p. 61 - 66 (2012/02/03)
Chiral alcohols are important as bioactive compounds or as precursors to such molecules. On the basis of the different antifungal properties of the enantiopure alcohol derivatives of 4′-chlorophenyl cyclopropyl ketone and benzyl 4′-chlorophenyl ketone, their enantioselective synthesis by chemical and biocatalytic methods was studied. The detoxification pathways by the phytopathogen fungus Botrytis cinerea are reported.
