112348-04-6Relevant academic research and scientific papers
Dirhodium(II) tetrakis[N-benzene-fused phthaloyl-(S)-piperidinonate] as a chiral lewis acid: Catalytic enantioselective aldol reactions of acetate-derived silylketene acetals and aldehydes
Washio, Takuya,Nakamura, Seiichi,Anada, Masahiro,Hashimoto, Shunichi
, p. 567 - 578 (2007/10/03)
A first example of chiral dirhodium(II) complex-catalyzed enantioselective Mukaiyama aldol reactions is described. The aldol addition reaction of methyl acetate-derived trimethylsilylketene acetal with specific aldehydes such as benzyloxyacetaldehyde and electron-poor aromatic aldehydes is effectively catalyzed by dirhodium(II) tetrakis[N-benzene-fused phthaloyl-(S)-piperidinonate] (1a), providing silylated aldol adducts in up to 94% ee.
Lasonolide A: Structural revision and total synthesis
Song, Ho Young,Joo, Jung Min,Kang, Jung Won,Kim, Dae-Shik,Jung, Cheol-Kyu,Kwak, Hyo Shin,Park, Jin Hyun,Lee, Eun,Hong, Chang Yong,Jeong, ShinWu,Jeon, Kiwan
, p. 8080 - 8087 (2007/10/03)
The proposed structure of lasonolide A was synthesized employing radical cyclization reactions of β-alkoxyacrylates for preparation of the tetrahydropyranyl units A and B, but the spectroscopic data did not match those of the natural product. Both enantio
Process for preparing optically active oxazolidinone derivative
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, (2008/06/13)
Disclosed is a process for preparing an optically active oxazolidinone derivative comprising allowing hydrazine to react on an optically active ester having a hydroxyl group at the 3-position which is represented by formula (II): wherein R1represents a lower alkyl group having 1 to 4 carbon atoms, a phenyl group, a methoxymethyl group, a benzyloxymethyl group, a benzyloxycarbonylaminomethyl group which may have a substituent or substituents on the benzene ring thereof, an acylaminomethyl group having 3 to 10 carbon atoms, or an alkyloxycarbonylaminomethyl group having 3 to 6 carbon atoms; R2and R3, which may be the same or different, each represent a hydrogen atom, a lower alkyl group having 1 to 4 carbon atoms, a phenyl group, an acetylaminomethyl group, a benzoylaminomethyl group, or a benzyl group; and * indicates an asymmetric carbon atom, and subjecting the resulting hydrazide to Curtius rearrangement.
Lasonolide A: Structural revision and synthesis of the unnatural (-)-enantiomer
Lee, Eun,Ho, Young Song,Jung, Won Kang,Kim, Dae-Shik,Jung, Cheol-Kyu,Jung, Min Joo
, p. 384 - 385 (2007/10/03)
Total synthesis of the unnatural (-)-enantiomer of lasonolide A was achieved starting from ethyl l-malate. The two tetrahydropyranyl fragments were prepared stereoselectively via radical cyclization reactions of β-alkoxyacrylates. The full structure of na
C2-Symmetric Cu(II) Complexes as Chiral Lewis Acids. Catalytic, Enantioselective Cycloadditions of Silyl Ketenes
Evans, David A.,Janey, Jacob M.
, p. 2125 - 2128 (2007/10/03)
(matrix presented) C2-Symmetric bis(oxazoline)-Cu(II) complexes (4a-g) catalyze the enantioselective [2 + 2] cycloaddition between (silyl)ketenes and chelating carbonyl substrates. A range of substituted β-lactones can be produced in excellent yields and selectivities. It was also found that (trimethylsilyl)-ketene (1) may also undergo a highly selective hetero Diels-Alder reaction with β,γ-unsaturated α-keto esters.
The bakers' yeast reductions of α- and β-keto ester derivatives in the presence of a sulfur compound
Hayakawa, Ryuuichirou,Nozawa, Kazumi,Kimura, Kimihiko,Shimizu, Makoto
, p. 7519 - 7528 (2007/10/03)
Improvement of the enantioselectivity and enhancement of the reactivity were achieved in the bakers' yeast reduction of the α- and β-keto ester derivatives by the addition of a sulfur compound. High enantioselectivity in the bakers' yeast reduction of keto esters was accomplished by using combination of an addition of a sulfur compound with an appropriate selection of the alcohol part of the ester.
C2-symmetric copper(II) complexes as Chiral Lewis acids. Scope and mechanism of catalytic enantioselective aldol additions of enolsilanes to (benzyloxy)acetaldehyde
Evans, David A.,Kozlowski, Marisa C.,Murry, Jerry A.,Burgey, Christopher S.,Campos, Kevin R.,Connell, Brian T.,Staples, Richard J.
, p. 669 - 685 (2007/10/03)
C2-Symmetric bis(oxazolinyl)pyridine (pybox)-Cu(II) complexes have been shown to catalyze enantioselective Mukaiyama aldol reactions between (benzyloxy)acetaldehyde and a variety of silylketene acetals. The aldol products are generated in high yields and in 92-99% enantiomeric excess using as little as 0.5 mol % of chiral catalyst [Cu((S,S)-Ph-pybox)](SbP6)2. With substituted silylketene acetals, syn reaction diastereo-selection ranging from 95:5 to 97:3 and enantioselectivities ≥95% are observed. Investigation into the reaction mechanism utilizing doubly labeled silylketene acetals indicates that the silyl-transfer step is intermolecular. Further mechanistic studies revealed a significant positive nonlinear effect, proposed to arise from the selective formation of the [Cu((S,S)-Ph-pybox)((R,R)-Ph-pybox)](SbF6)2 2:1 ligand:metal complex. A stereochemical model is presented in which chelation of (benzyloxy)acetaldehyde to the metal center to form a square pyramidal copper intermediate accounts for the observed sense of induction. Support for this proposal has been obtained from double stereodifferentiating reactions, EPR spectroscopy, ESI spectrometry, and, ultimately, the X-ray crystal structure of the aldehyde bound to the catalyst. The C2-symmetric bis(oxazolinyl)-Cu(II) complex [Cu((S,S)-tert-Bu-box)](OTf)2 is also an efficient catalyst for the aldol reaction, but the scope with this system is not as broad.
Control of enantioselectivity in the bakers' yeast reduction of β-keto ester derivatives in the presence of a sulfur compound
Hayakawa, Ryuuichirou,Nozawa, Kazumi,Shimizu, Makoto,Fujisawa, Tamotsu
, p. 67 - 70 (2007/10/03)
Improvement of the enantioselectivity and enhancement of the reactivity were achieved in the bakers' yeast reduction of the β-keto ester derivatives by the addition of a sulfur compound.
(3R,5S)-3,5,6-trihydroxyhexanoic acid derivative and production method thereof
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, (2008/06/13)
A (3R,5S)-3,5,6-trihydroxyhexanoic acid derivative and a process of producing the (3R,5S)-3,5,6-trihydroxyhexanoic acid derivative which comprises the step of enantioselectively hydrogenating an (S)-5,6-dihydroxy-3-oxohexanoic acid derivative with a speci
