192565-56-3Relevant academic research and scientific papers
(R)-BINOL-6,6’-bistriflone: Shortened Synthesis, Characterization, and Enantioselective Catalytic Applications
André-Barrès, Christiane,Castellan, Tessa,Fabing, Isabelle,Génisson, Yves,Gaspard, Hafida,Gornitzka, Heinz,Mouhtady, Omar,Saffon-Merceron, Nathalie
, p. 6674 - 6681 (2021/12/31)
The title compound, characterized by X-ray crystallography, was accessed in 4 steps with 92 % ee. and 25 % yield from an O-protected (R)-BINOL precursor. This revised synthetic route relied on a chlorosulfonylation reaction, as a shortcut to a previously developed sequence requiring the use of toxic SO2 gas and bromine. The strongly electron-impoverished (R)-6,6′-Tf2-BINOL proved an effective ligand in metal-catalyzed enantioselective transformations such as a Zr-based Mannich-type reaction. The catalytic species was characterized by X-ray crystallography as a unique tetrameric metal cluster. The 6,6′-bistriflone groups also allowed to exalt the H-bond donor capacity of the BINOL moiety, as illustrated in an organocatalyzed Morita-Baylis-Hillman transformation. Theoretical study indicated that the 6,6′-bistriflone groups induce a drop of the phenol acidity of 5 pKa units in DMSO. Overall, this work simplified the access, completed the characterization, and confirmed the potential of (R)-6,6′-Tf2-BINOL as a promising platform to further elaborate activated chiral metal ligands or organocatalysts.
An aromatic ion platform for enantioselective Br?nsted acid catalysis
Gheewala, Chirag D.,Collins, Bridget E.,Lambert, Tristan H.
, p. 961 - 965 (2016/03/08)
Chiral acid catalysts are useful for the synthesis of enantioenriched small molecules, but the standard catalysts require laborious and expensive preparations. Here, we describe a chiral Br?nsted acid prepared in one step from naturally occurring (-)-menthol and readily available 1,2,3,4,5-pentacarbomethoxycyclopentadiene. Aromatic stabilization serves as a key contributing factor to the potent acidity of the resulting compound, which is shown to catalyze both Mukaiyama-Mannich and oxocarbenium aldol reactions with high efficiency and enantioselectivity. Catalyst loadings as low as 0.01 mole percent and preparative scalability (25 grams) are demonstrated. Alternative amide catalysts are also shown to be promising platforms. In addition to proton catalysis, a chiral anion pathway is demonstrated to be viable with this catalyst system.
A Powerful Chiral Phosphoric Acid Catalyst for Enantioselective Mukaiyama–Mannich Reactions
Zhou, Fengtao,Yamamoto, Hisashi
, p. 8970 - 8974 (2016/07/26)
A new BINOL-derived chiral phosphoric acid bearing 2,4,6-trimethyl-3,5-dinitrophenyl substituents at the 3,3′-positions was developed. The utility of this chiral phosphoric acid is demonstrated by a highly enantioselective (ee up to >99 %) and diastereoselective (syn/anti up to >99:1) asymmetric Mukaiyama–Mannich reaction of imines with a wide range of ketene silyl acetals. Moreover, this method was successfully applied to the construction of vicinal tertiary and quaternary stereogenic centers with excellent diastereo- and enantioselectivity. Significantly, BINOL-derived N-triflyl phosphoramide constitutes a complementary catalyst system that allows the title reaction to be applied to more challenging imines without an N-(2-hydroxyphenyl) moiety.
ASYMMETRIC-SYNTHESIS CATALYST BASED ON CHIRAL BROENSTED ACID AND METHOD OF ASYMMETRIC SYNTHESIS WITH THE CATALYST
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Page/Page column 38, (2010/11/08)
A compound usable as an asymmetric synthesis catalyst which can be easily synthesized without using any metal such as a lanthanoid group element; a method of asymmetric synthesis with the compound; and a chiral compound obtained by the asymmetric synthesis method. A Broensted acid is used as a catalyst in asymmetric synthesis, the chiral Broensted acid being represented by formula (1) below or formula (3) below. The asymmetric synthesis method employs the catalyst. Asymmetric synthesis with the catalyst gives a chiral compound.
A novel dinuclear chiral niobium complex for Lewis acid catalyzed enantioselective reactions: Design of a tridentate ligand and elucidation of the catalyst structure
Kobayashi, Shu,Arai, Kenzo,Shimizu, Haruka,Ihori, Yoichi,Ishitani, Haruro,Yamashita, Yasuhiro
, p. 761 - 764 (2007/10/03)
Two's company: By using a novel chiral ligand a dinuclear chiral niobium catalyst for highly enantioselective Mannich-type reactions was developed. Tridentate binol derivatives provide excellent asymmetric environments around the niobium atom, and the Man
