title: "Matched/mismatched" diastereomeric dirhodium(II) carboxamidate catalyst pairs. Structure-selectivity correlations in diazo decomposition and hetero-Diels-Alder reactions.
abstract: Homo-ligated dirhodium(II) carboxamidates provide well-defined structural frameworks with which to investigate catalyst-controlled multiple asymmetric induction ("match/mismatch" effects). Diastereomeric pairs of methyl 2-oxoimidazolidine-4(S)-carboxylate ligands containing 2-phenylcyclopropane (4S,2'S,3'S-HMCPIM and 4S,2'R,3'R-HMCPIM) and N-benzenesulfonylproline (4S,2'S-HBSPIM and 4S,2'R-HBSPIM) attachments at the 1-N-acyl site have been prepared; the resulting (cis-2,2)-Rh(2)L(4) compounds have been produced in good yields, and the X-ray crystal structure of each dirhodium(II) compound has been obtained. The incorporation of additional stereocenters into the dirhodium(II) ligands leads to recognizable levels of double asymmetric induction for C-H insertion, cyclopropanation, and hetero-Diels-Alder cycloaddition applications. The configurationally "matched" cases provide modest increases in enantioselectivity for intramolecular C-H insertion reactions relative to the model catalyst Rh(2)(MPPIM)(4), but applications of the configurationally mismatched catalysts result in significant lowering of enantioselectivity. The Rh(2)(BSPIM)(4) catalysts show the highest degree of differential selectivity. Hetero-Diels-Alder reactions show inverse behavior from the configurationally matched and mismatched Rh(2)L(4) catalysts to that found in the metal carbene transformations.
authors.affiliation: Department of Chemistry and Biochemistry, The University of Maryland, College Park, MD 20742, USA. mdoyle3@umd.edu
authors.forename: Michael P
authors.initials: MP
authors.lastname: Doyle
authors.forename: John P
authors.initials: JP
authors.lastname: Morgan
authors.forename: James C
authors.initials: JC
authors.lastname: Fettinger
authors.forename: Peter Y
authors.initials: PY
authors.lastname: Zavalij
authors.forename: John T
authors.initials: JT
authors.lastname: Colyer
authors.forename: Daren J
authors.initials: DJ
authors.lastname: Timmons
authors.forename: Michael D
authors.initials: MD
authors.lastname: Carducci
mesh_terms: D002384:Catalysis; D018360:Crystallography, X-Ray; D003500:Cyclization; D006841:Hydrocarbons, Aromatic / Q000737:chemistry; D007700:Kinetics; D008958:Models, Molecular; D008968:Molecular Conformation; D009942:Organometallic Compounds / Q000737:chemistry*; D012238:Rhodium / Q000737:chemistry*; D013237:Stereoisomerism; D013329:Structure-Activity Relationship
chemical_list: D006841:Hydrocarbons, Aromatic; D009942:Organometallic Compounds; D012238:Rhodium