- Selective Asymmetric Transfer Hydrogenation of α-Substituted Acetophenones with Bifunctional Oxo-Tethered Ruthenium(II) Catalysts
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A practical method for the asymmetric transfer hydrogenation of α-substituted ketones was developed utilizing oxo-tethered N-sulfonyldiamine-ruthenium complexes. Reduction by HCO2H and HCO2K in a mixed solvent of EtOAc/H2O allowed for the selective synthesis of halohydrins from 2-bromoacetophenone (98%) and 2-chloroacetophenone (>99%), leading to suppressed undesired side reactions stemming from formylation under the typical reaction conditions using an azeotropic 5:2 mixture of HCO2H and Et3N. A range of functional groups, such as halogens, methoxy, nitro, dimethylamino, and ester groups, were well tolerated, highlighting the potential of this method. Nearly complete selectivity with a preferable ee was maintained even with a substrate/catalyst (S/C) ratio of 5000. This catalyst system was also effective for the asymmetric reduction of α-sulfonated ketones without eroding the leaving group. (Figure presented.).
- Yuki, Yamato,Touge, Taichiro,Nara, Hideki,Matsumura, Kazuhiko,Fujiwhara, Mitsuhiko,Kayaki, Yoshihito,Ikariya, Takao
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supporting information
p. 568 - 574
(2017/12/13)
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- METHOD FOR THE PREPARATION OF OPTICALLY ACTIVE 2-SULFONYLOXY-1-PHENYLETHANOL DERIVATIVES
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Optically active 2-sulfonyloxy-1-phenylethanol derivative of formula (II) can be prepared easily and selectively by the method of the present invention using an asymmetric reduction of an α-sulfonyloxy acetophenone compound with a rhodium catalyst having petamethylcyclopentadienyl group and a hydrogen donor, and the compound of formula (II) obtained in the inventive method exhibits a higher e.e. (enantiomer excess) value than that of the products in the conventional methods.
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Page/Page column 20
(2008/12/05)
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- Synthesis, biological, and chiroptical activity of 3-phenyl-clavams
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The [2+2]cycloaddition of chlorosulfonyl isocyanate to simple vinyl ethers derived from the 2-O-sulfonylated (R) and (S) 1-phenyl-1,2-ethanediol leads to 4-alkoxy-azetidin-2-ones with a moderate stereoselectivity. The cycloaddition to analogous (Z)-propenyl ethers proceeds stereospecifically with the retention of the olefin configuration. The intramolecular alkylation of β-lactam nitrogen atom furnished all possible stereoisomers of 3-phenyl- and 6-methyl-3-phenyl-clavams. The biological and chiroptical activity of synthesized clavams was investigated. The (3R,5R)-diastereomer 30 showed higher inhibition of bacterial enzymes than other related compounds.
- Cierpucha, Maciej,Solecka, Jolanta,Frelek, Jadwiga,Szczukiewicz, Patrycja,Chmielewski, Marek
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p. 405 - 416
(2007/10/03)
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- Process for the preparation of enantiomerically pure 3-phenyl-3-hydroxypropylamine
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The present invention relates to an improved process for the synthesis of enantiomerically pure 3-phenyl-3-hydroxypropylamine of formula I; more particularly the present invention relates to the said process using styrene; the synthetic strategy features a Sharpless asymmetric dihydroxylation (SAD) route to the target compound, using styrene, a readily accessible starting material gives the optically pure dihydroxy compound (ee >97%; the selective monotosylation of primary alcohol, nucleophilic displacement by cyano and subsequent reduction to amino group furnishes the desired 3-phenyl-3-hydroxypropylamine in enatiomerically pure form, a key intermediate in the synthesis of variety of oxetine related anti-depressant drugs.
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- Acetalsulfonate derivative, process for producing the same, and process for producing styrene oxide derivative
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There are provided an acetalsulfonate derivative useful as an intermediate for medicines and agricultural chemicals, a process for industrially producing the derivative, and a process for industrially producing a styrene oxide derivative from the acetalsulfonate derivative or from a mandelic acid derivative. A process for producing an acetalsulfonate derivative which comprises a first step of esterifying a mandelic acid derivative to form a mandelic ester derivative, a second step of protecting the mandelic ester derivative by an acetal to form an acetal derivative, a third step of reducing the acetal derivative to form an ethanediol derivative and a fourth step of reacting the ethanediol derivative with a sulfonyl chloride derivative. A process for producing a styrene oxide derivative which comprises a deprotecting step of deacetalizing the acetalsulfonate derivative and a step of epoxidizing the sulfonate derivative obtained in the deprotecting step with the aid of a base catalyst.
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Page/Page column 14
(2010/01/31)
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