2406-21-5Relevant articles and documents
Osmium(0)-Catalyzed C-C Coupling of Ethylene and α-Olefins with Diols, Ketols, or Hydroxy Esters via Transfer Hydrogenation
Park, Boyoung Y.,Luong, Tom,Sato, Hiroki,Krische, Michael J.
, p. 8585 - 8594 (2016)
Osmium(0) complexes derived from Os3(CO)12 and XPhos (2-dicyclohexylphosphino-2′,4′,6′-triisopropylbiphenyl) catalyze the C-C coupling of α-hydroxy esters 1a-1i, α-ketols 1j-1o, or 1,2-diols dihydro-1j-1o with ethylene 2a to form ethylated tertiary alcohols 3a-3o. As illustrated in couplings of 1-octene 2b with vicinally dioxygenated reactants 1a, 1b, 1i, 1j, 1k, 1m, higher α-olefins are converted to adducts 4a, 4b, 4i, 4j, 4k, 4m with complete levels of branched regioselectivity. Oxidation level independent C-C coupling is demonstrated by the reaction of 1-octene 2b with diol dihydro-1k, α-ketol 1k, and dione dehydro-1k. Functionalized olefins 2c-2f react with ethyl mandelate 1a to furnish adducts 5a-8a as single regioisomers. The collective data, including deuterium labeling studies, are consistent with a catalytic mechanism involving olefin-dione oxidative coupling to form an oxa-osmacyclopentane, which upon reductive cleavage via hydrogen transfer from the secondary alcohol reactant releases the product of carbinol C-alkylation with regeneration of the ketone. Single-crystal X-ray diffraction data of the dinuclear complex Os2(CO)4(O2CR)2(XPhos)2 and the trinuclear complex Os3(CO)11(XPhos) are reported. These studies suggest increased π-backbonding at the stage of the metal-olefin π-complex plays a critical role in facilitating alkene-carbonyl oxidative coupling, as isostructural ruthenium(0) complexes, which are weaker π-donors, do not catalyze the transformations reported herein.
Synthesis and structure-activity relationship studies for hydantoins and analogues as voltage-gated sodium channel ligands
Zha, Congxiang,Brown, George B.,Brouillette, Wayne J.
, p. 6519 - 6528 (2007/10/03)
We previously developed a preliminary 3-D QSAR model for the binding of 14 hydantoins to the neuronal voltage-gated sodium channel; this model was successful in designing an effective non-hydantoin ligand. To further understand structural features that result in optimum binding, here we synthesized a variety of compound classes and evaluated their binding affinities to the neuronal voltage-gated sodium channel using the [3H]-batrachotoxinin A 20-α-benzoate ([3H]BTX-B) binding assay. In order to understand the importance of the hydantoin ring for good sodium channel binding, related non-hydantoins such as hydroxy amides, oxazolidinediones, hydroxy acids, and amino acids were included. Two major conclusions were drawn: (1) The hydantoin ring is not critical for compounds with long alkyl side chains, but it is important for compounds with shorter side chains. (2) Relative to Khodorov's pharmacophore, which contains two hydrophobic regions, a third hydrophobic region may enhance binding to provide nanomolar inhibitors.
The First Catalytic Asymmetric Addition of Dialkylzincs to α-Ketoesters
DiMauro, Erin F.,Kozlowski, Marisa C.
, p. 3781 - 3784 (2007/10/03)
(Matrix Presented) The first catalytic, enantioselective addition of organozinc reagents to α-ketoesters is described. Modular bifunctional salen catalysts that contain Lewis acid and Lewis base activating groups accelerate the carbonyl addition to a much greater extent than the competing carbonyl reduction. α-Hydroxyesters containing new quaternary stereogenic centers are obtained in high yield and moderate enantiomeric excess. Enrichment to 98% ee can be effected by recrystallization of the corresponding α-hydroxy acid.
