Tetrakis[(4S)‐4‐phenyloxazolidin‐2‐one]dirhodium(II) and Its Catalytic Applications for Metal Carbene Transformations

Abstract

Introduction. -We previously reported that dirhodium(I1) catalysts possessing chiral methyl 5-oxopyrrolidine-Zcarboxylate ligands'), [Rh2{(2S)-mepy},] and [Rh2{(2R)-mepy},], are exceptionally effective for highly enantioselective metal carbene transformations [ 1-71. These catalysts were prepared by ligand substitution from dirhodium(I1) acetate, and their design places 2 0 and 2 N donor atoms from the four amide ligands on each octahedral Rh-atom in a cis-configuration. The asymmetric center of the chiral oxopyrrolidinecarboxylate ligand is the sp3-hybridized C-atom bonded to the N donor

Synthesis of 2‐Azabicyclo[4.1.0]heptanes through Stereoselective Cyclopropanation Reactions

“…[17] Two chiral rhodium catalysts, selected from the most frequently used in the literature, and different from those tested with previous substrates, because those had given unsatisfactory results, were used with (Ϯ)-10a. Rh 2 [(4S)-MEOX] 4 [18] and Rh 2 [(5S)-MEPY] 4 [19] (Entries 5 and 6) gave cyclopropanes in similar chemical yields, although the diastereoselectivity was lower than for copper catalysts. Interestingly, in the reaction in the presence of Rh 2 [(4S)-MEOX] 4 the major product was anti-cis-13a.…”

Asymmetric Catalysis with a Phosphoramidite Derived from (−)-(aR)- [1,1′-Binaphthalene]-8,8′-diol

“…IR (CHCl 3 ): 3683m, 3618s, 3482w, 3014s, 2400s, 1522s, 1420w, 1272w, 1207s, 1046s, 928m, 878w, 764s, 676s. 3080m, 3050m, 3015m, 2970s, 2920s, 2850s, 1680s, 1579m, 1450s, 1375m, 1320w, 1260m, 1245w, 1190w, 1180m, 1160w, 1060w, 1002w, 950w, (18) was carried out with 5% of catalyst as described previously [22] [24]. …”

Rhodium(II)‐Catalyzed Decomposition of β,γ‐Unsaturated Diazo Compounds

“…1s 16 An attempt was made to suppress the undesired OH insertion of the metallocarbene by using less acidic or less nucleophilic solvents such iiS t-BuOH or CF,CH,OH, etc., but the reaction course could not be diverted in favor of 14+15+16. In addition, no identifiable products were formed when the reaction was carried out in the absence of any intercepting reagent.…”