192135-52-7Relevant articles and documents
Chloroform is not solvent but activator for cobalt complex catalyst of enantioselective borohydride reduction
Kokura, Ai,Tanaka, Saiko,Teraoka, Haruna,Shibahrara, Atsushi,Ikeno, Taketo,Nagata, Takushi,Yamada, Tohru
, p. 26 - 27 (2007)
For the enantioselective borohydride reduction of carbonyl compounds catalyzed by the optically active ketoiminatocobalt complexes, chloroform has been employed as a unique solvent for achieving a high enantioselectivity, whereas it was found that a catal
Chiral ferrocene P-N-N ligand with high steric hindrance, and preparation method and application thereof
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Paragraph 0125-0129, (2018/01/13)
The invention provides a chiral ferrocene P-N-N ligand compound with high steric hindrance, and a preparation method and application thereof, specifically application of the chiral ferrocene P-N-N ligand compound to asymmetric catalytic hydrogenation of beta-keto ester compounds. The preparation method for the chiral ferrocene P-N-N ligand compound with high steric hindrance comprises the following steps: dissolving a chiral ferrocenephosphine-amine compound and a pyridone compound in a reaction solvent; adding active Al2O3 and a dehydrating agent; carrying out a reflux condensation reaction; then carrying out re-dissolving in absolute ethyl alcohol after filtering and desolventizing; adding a palladium/carbon catalyst and carrying out a hydrogenation reaction in an autoclave under a certain reaction pressure; and then successively carrying out filtration, desolventizing and column chromatographic treatment so as to obtain the desired chiral ferrocene P-N-N ligand compound with high steric hindrance. The chiral ferrocene P-N-N ligand compound with high steric hindrance in the invention can be used for asymmetric catalytic hydrogenation of beta-keto ester and can realize high-yield, high-diastereoselectivity high-enantioselectivity preparation of chiral beta-hydroxy ester.
Lewis base activation of Lewis acids: Catalytic, enantioselective addition of silyl ketene acetals to aldehydes
Denmark, Scott E.,Beutner, Gregory L.,Wynn, Thomas,Eastgate, Martin D.
, p. 3774 - 3789 (2007/10/03)
The concept of Lewis base activation of Lewis acids has been reduced to practice for catalysis of the aldol reaction of silyl ketene acetals and silyl dienol ethers with aldehydes. The weakly acidic species, silicon tetrachloride (SiCl4), can b
Diastereoselective radical debromination approach toward divergent syntheses of syn- and anti-propionate units, coupled with enantioselective and/or diastereoselective Lewis acid-promoted aldol reactions
Kiyooka, Syun-Ichi
, p. 2897 - 2910 (2007/10/03)
A practical methodology directed to the enantioselective synthesis of polypropionate backbones, available for the synthesis of polyketide natural products, has been developed by iterative enantio- and diastereoselective Lewis acid-promoted aldol reactions, followed by diastereoselective radical debromination reactions. A chiral oxazaborolidinone-promoted aldol reaction of a racemic aldehyde, derived from 2-methyl-1,3-propanediol, with a silylketene acetal from ethyl 2-bromopropionate, resulted in highly enantioselective formation of the corresponding bromo aldol adduct, followed by radical debromination with Bu3SnH in the presence of Et3B to divergently give syn- and anti-propionate aldols, which are versatile stereotriads. Furthermore, elongation of the propionate units has also been achieved: the BF3·OEt2-promoted aldol reaction of chiral syn- and anti-α-methyl-β-protected-oxy aldehydes with the silyl nucleophile proceeded with essentially complete syn-selectivity while the TiCl4-promoted aldol reaction resulted in fairly good anti-selectivity. The resulting bromo aldol adducts were divergently debrominated by the radical reduction to give a complete set of stereotetrads.
Dynamic kinetic resolution with enantioselective borohydride reduction catalyzed by optically active β-ketoiminato cobalt(II) complexes: Highly diastereo- and enantioselective preparation of optically active anti-aldol compounds
Ohtsuka, Yuhki,Miyazaki, Daichi,Ikeno, Taketo,Yamada, Tohru
, p. 24 - 25 (2007/10/03)
Optically active anti-2-alkyl-3-hydroxy esters were stereo-selectively obtained from the corresponding 2-alkyl-3-keto esters using enantioselective borohydride reduction along with dynamic kinetic resolution in the presence of optically active β-ketoimina
A divergent synthesis of essentially enantiopure syn- and anti-propionate aldol adducts based on the chiral 1,3,2-oxazaborolidin-5-one-promoted asymmetric aldol reaction followed by diastereoselective radical reduction
Kiyooka,Shahid
, p. 1485 - 1495 (2007/10/03)
Essentially, enantiopure syn- and anti-propionate aldol adducts were divergently synthesized using a novel strategy which utilizes both the highly enantioselective 1,3,2-oxazaborolidin-5-one-promoted aldol reaction with a ketene silyl acetal derived from ethyl 2-bromo propionate and a highly diastereoselective radical debromination reaction. These procedures provide yields that increase to a level available for practical synthesis.
Superior substrate control on diastereoselection in boric Lewis acid-promoted aldol reactions. Asymmetric synthesis of a 3,4-syn homologous series of ethyl 3,5-dihydroxy-2,4-dimethyl-5-phenylpentanoates
Kiyooka, Syun-ichi,Shahid, Kazi A.,Murai, Kazunori,Li, Yong-Nan,Okazaki, Momotoshi,Shuto, Yoshihiro
, p. 2343 - 2349 (2007/10/03)
The BF3·OEt2-promoted aldol reaction of chiral syn- and anti-α-methyl-β-siloxy aldehydes with a silyl ketene acetal resulted in essentially complete syn Felkin selection. Even in the asymmetric aldol reaction using chiral oxazaboroli
A practical synthesis of essentially enantiopure syn-propionate aldols using a chiral oxazaborolidinone-promoted asymmetric aldol reaction coupled with radical reduction
Kiyooka, Syun-ichi,Shahid, Kazi A.,Hena, Mostofa A.
, p. 6447 - 6449 (2007/10/03)
Essentially enantiopure syn-propionate aldols (>98% ee) were prepared by a chiral oxazaborolidinone-promoted asymmetric aldol reaction, followed by a diastereoselective radical reduction with Bu3SnH and Et3B, which was carried out un
Highly enantioselective synthesis of syn- and anti-propionate aldols without diastereoselection in the chiral oxazaborolidinone-promoted aldol reaction with a silyl ketene acetal derived from ethyl 2- (methylthio)propionate
Hena, Mostofa Abu,Terauchi, Saori,Kim, Chul-Sa,Horiike, Michio,Kiyooka, Syun-Ichi
, p. 1883 - 1890 (2007/10/03)
A mixture of syn- and anti-aldol products containing an α-methylthio group were obtained in good yields with high enantioselectivities in the chiral oxazaborolidinone-promoted aldol reactions of a novel silyl ketene acetal, derived from ethyl 2-(methylthio)propionate, with aldehydes. Subsequent desulfurization resulted in an effective preparation of essentially enantiopure syn- and anti-propionate aldols which were separable.
Enantioselective aldol reaction using bornane-2,3-diol-aluminum complex as a chiral Lewis acid
Shimizu, Makoto,Kawamoto, Manabu,Yamamoto, Yasushi,Fujisawa, Tamotsu
, p. 501 - 502 (2007/10/03)
β-Hydroxy ester was formed in high enantiomeric excess by the reaction of ketene silyl acetal with aldehyde in the presence of a chiral Lewis acid prepared from diethylaluminum chloride and chiral diol derived from (+)-camphor.
