Kim, In Su; Ngai, Ming-Yu; Krische, Michael J. published the artcile< Enantioselective Iridium-Catalyzed Carbonyl Allylation from the Alcohol or Aldehyde Oxidation Level via Transfer Hydrogenative Coupling of Allyl Acetate: Departure from Chirally Modified Allyl Metal Reagents in Carbonyl Addition>, Application In Synthesis of 139139-86-9, the main research area is alc enantioselective iridium catalyzed carbonyl allylation; oxidation level transfer hydrogenative coupling allyl acetate; departure chirally metal reagent addition crystallog; aldehyde enantioselective iridium catalyzed carbonyl allylation.
Under the conditions of transfer hydrogenation employing an iridium catalyst generated in situ from [Ir(cod)Cl]2, chiral phosphine ligand (R)-BINAP or (R)-Cl,MeO-BIPHEP, and m-nitrobenzoic acid, allyl acetate couples to allylic, aliphatic, or benzylic alcs. to furnish products of carbonyl allylation with exceptional levels of asym. induction. The very same set of optically enriched carbonyl allylation products are accessible from enals , aliphatic aldehydes , and aryl aldehydes, using iridium catalysts ligated by (-)-TMBTP or (R)-Cl,MeO-BIPHEP under identical conditions, but employing isopropanol as a hydrogen donor. A catalytically active cyclometallated complex V, which arises upon ortho-C-H insertion of iridium onto m-nitrobenzoic acid, was characterized by single-crystal x-ray diffraction. The results of isotopic labeling are consistent with intervention of sym. iridium π-allyl intermediates or rapid interconversion of σ-allyl haptomers through the agency of a sym. π-allyl. Competition experiments demonstrate rapid and reversible hydrogenation-dehydrogenation of the carbonyl partner in advance of C-C coupling. However, the coupling products, which are homoallylic alcs., experience very little erosion of optical purity by way of redox equilibration under the coupling conditions, although isopropanol, a secondary alc., may serve as terminal reductant. A plausible catalytic mechanism accounting for these observations is proposed, along with a stereochem. model that accounts for the observed sense of absolute stereoinduction. This protocol for asym. carbonyl allylation transcends the barriers imposed by oxidation level and the use of preformed allyl metal reagents.
Journal of the American Chemical Society published new progress about Alcohols, homoallylic Role: SPN (Synthetic Preparation), PREP (Preparation). 139139-86-9 belongs to class chiral-phosphine-ligands, and the molecular formula is C44H40P2, Application In Synthesis of 139139-86-9.
Referemce:
Phosphine ligand,
Chiral phosphine ligands in asymmetric synthesis. Molecular structure and absolute configuration of (1,5-cyclooctadiene)-(2S,3S)-2,3-bis(diphenylphosphino)butanerhodium(I) perchlorate tetrahydrofuran solvate