Tricyclic Sulfoxide–Alkene Hybrid Ligands for Chiral Rh(I) Complexes: The “Matched” Diastereomer Catalyzes Asymmetric C–C Bond Formations
Heinemann, Frank W.
KAUST DepartmentChemical Science Program
KAUST Catalysis Center (KCC)
Physical Science and Engineering (PSE) Division
Online Publication Date2020-03-19
Print Publication Date2020-04-27
Embargo End Date2021-03-19
Permanent link to this recordhttp://hdl.handle.net/10754/662258
MetadataShow full item record
AbstractDeprotonation of phenyldibenzo[b,f]tropylidene (8) with LDA/t-BuOK followed by quenching with either diastereomer of inexpensive glucose-based t-Bu-sulfinate (R)- or (S)-11 affords a sulfoxide−alkene hybrid ligand as the diastereomeric pairs (SS,SC)-9/(SS,RC)-10 and (RS,RC)-9/ (RS,SC)-10, respectively, which via chromatographic/recrystallization may be separated into the four isomers. The optically pure diastereomeric ligands (SS,SC)-9 and (SS,RC)-10 react with [RhCl(coe)2]2 to form the dinuclear complexes (RS,SC)-11 and (RS,RC)-12, respectively, in which the bidentate ligands coordinate the metal centers through the sulfur and alkene donor functions. These complexes catalyze the conjugate addition of arylboronic acids to cyclic Michael acceptors with enantioselectivities of up to 99% ee. DFT calculations show the preponderant influence of planar chirality of the ligand alkene function. The enantioselectivity switch observed between (RS,SC)-11 and (RS,RC)-12 is explained by the inverted cis−trans coordinations of the substrate molecules in catalytic steps.
CitationNikol, A., Zhang, Z., Chelouan, A., Falivene, L., Cavallo, L., Herrera, A., … Dorta, R. (2020). Tricyclic Sulfoxide–Alkene Hybrid Ligands for Chiral Rh(I) Complexes: The “Matched” Diastereomer Catalyzes Asymmetric C–C Bond Formations. Organometallics. doi:10.1021/acs.organomet.0c00094
SponsorsWe thank Prof. Anthony Linden (University of Zurich) for solving the crystal structure of 8 and Ms. Christina Wronna for carrying out the elemental analyses. Financial support by Friedrich–Alexander University and King Abdullah University of Science and Technology (KAUST) is acknowledged. For computer time, this research used the resources of the Supercomputing Laboratory (KSL) at KAUST.
PublisherAmerican Chemical Society (ACS)
RelationsIs Supplemented By: