- Enantiopure β-hydroxy morpholine amides from terminal epoxides by carbonylation at 1 atm
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Keeping the CO pressure down is a crucial, practical feature of the new methodology for the carbonylation of terminal epoxides. β-Hydroxy morpholinyl amides are generated directly in optically pure form [Eq. (1)], and these building blocks can be applied in a variety of acyl transfer reactions. A useful illustration is provided in the concise synthesis of δ-hydroxy-β-ketoesters, key intermediates for the preparation of the statin class of HMG-CoA reductase inhibitors.
- Goodman, Steven N.,Jacobsen, Eric N.
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Read Online
- Synthesis method of rosuvastatin calcium side chain key intermediate
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The invention discloses a synthesis method of a rosuvastatin calcium side chain key intermediate and provides a preparation method of the rosuvastatin calcium side chain key intermediate. (S)-2-(epoxypropane-2-yl)methyl acetate is taken as a starting material and subjected to a condensation reaction, a ring opening reaction, a reduction reaction, a hydroxyl group protecting reaction and a debenzylation reaction. The method is simple and convenient to operate, easy in separation and purification, higher in yield and capable of obtaining the intermediate with higher chemical purity and optical purity.
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Paragraph 0039; 0040
(2018/04/28)
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- Ru-catalyzed asymmetric hydrogenation of γ-heteroatom substituted β-keto esters
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A series of enantiomerically pure γ-heteroatom substituted β-hydroxy esters were synthesized with high enantioselectivities (up to 99.1% ee) by hydrogenation of γ-heteroatom substituted β-keto esters in the presence of Ru-(S)-SunPhos catalyst. These asymmetric hydrogenations provide key building blocks for a variety of naturally occurring and biologically active compounds.
- Fan, Weizheng,Li, Wanfang,Ma, Xin,Tao, Xiaoming,Li, Xiaoming,Yao, Ying,Xie, Xiaomin,Zhang, Zhaoguo
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experimental part
p. 9444 - 9451
(2012/01/13)
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- Enantioselective synthesis of oasomycin A, part II: Synthesis of the C29-C46 subunit
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(Chemical Equation Presented) Putting the pieces together: The total synthesis of the natural macrolide oasomycin A has been realized. Key fragment couplings include an anti-Felkin selective aldol addition (green), Kociensky-Julia olefinations (red), and
- Evans, David A.,Nagorny, Pavel,Reynolds, Dominic J.,McRae, Kenneth J.
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p. 541 - 544
(2008/02/02)
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- Efficient lipase-catalyzed kinetic resolution of 4-arylmethoxy-3-hydroxybutanenitriles: application to an expedient synthesis of a statin intermediate
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The kinetic resolution of 4-arylmethoxy-3-hydroxybutanenitriles was investigated by lipase-catalyzed transesterification in organic solvents. A high enantioselectivity was obtained via reaction with vinyl acetate in a mixed solvent (n-heptane/acetonitrile 1:1), which was catalyzed by the lipase from Artgribacter sp. A better selectivity was demonstrated when the number of substituents on the aryl ring increased. (S)-4-Arylmethoxy-3-hydroxybutanenitriles can be obtained with enantiomeric excesses of up to 98.0% by this method. Furthermore we have developed a novel route to synthesize tert-butyl (S)-6-benzyloxy-5-hydroxy-3-oxohexanoate, a key intermediate for the preparation of HMG-CoA reductase inhibitors (statins).
- Sun, Fenglai,Xu, Gang,Wu, Jianping,Yang, Lirong
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p. 2907 - 2913
(2007/10/03)
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- Synthesis of ethyl and t-butyl (3R,5S)-dihydroxy-6-benzyloxy hexanoates via diastereo- and enantioselective microbial reduction
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Previously we have demonstrated the reduction of ethyl diketoester 4 to the corresponding dihydroxy ester 6a by Acinetobacter sp. SC13874. Recently we screened more than 100 cultures for microbial reduction of both the ethyl and t-butyl diketoesters 4 and
- Guo, Zhiwei,Chen, Yijun,Goswami, Animesh,Hanson, Ronald L.,Patel, Ramesh N.
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p. 1589 - 1602
(2007/10/03)
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- C2-symmetric copper(II) complexes as Chiral Lewis acids. Scope and mechanism of catalytic enantioselective aldol additions of enolsilanes to (benzyloxy)acetaldehyde
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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.
- Evans, David A.,Kozlowski, Marisa C.,Murry, Jerry A.,Burgey, Christopher S.,Campos, Kevin R.,Connell, Brian T.,Staples, Richard J.
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p. 669 - 685
(2007/10/03)
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- Practical large scale synthesis of tert-butyl (3R,5S)-6-hydroxy-3,5-O-isopropylidene-3,5-dihydroxyhexanoate: Essential building block for HMG-CoA reductase inhibitors
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Title compound 7 (96% ee, > 98% de) is synthesized enantioselectively in six steps (36% overall yield) from the commercial β-keto ester 8 on a multi-kg scale.
- Beck,Jendralla,Kesseler
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p. 1014 - 1018
(2007/10/02)
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- Process for preparing tert-butyl (3R,5S)-6-hydroxy-3,5--O--isopropylidene-3,5-dihydroxyhexanoate
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A novel process is described for preparing tert-butyl (3R, 5S ) 6-hydroxy-3,5-O-isopropylidene-3,5-dihydroxyhexanoate of the formula I STR1 which is a valuable structural element for preparing inhibitors of HMG-CoA reductase.
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- Asymmetric Hydrogenation of 3,5-Dioxoesters Catalyzed by Ru-binap Complex: A Short Step Asymmetric Synthesis of 6-Substituted 5,6-dihydro-2-pyrones
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Asymmetric hydrogenation of 3,5-dioxoesters 1a-c using Ru2Cl4((R) or (S)-binap)2(NEt3) as the catalyst gave dominantly anti 3,5-dihydroxyesters 2, which were then converted into unsaturated lactones 5a-b (ca. 80percent e.e.).The pathway of the hydrogenation reaction was also investigated by asymmetric hydrogenation of (R)- or (S)-5-hydroxy-3-oxoesters 8a-c.It was revealed that the Ru-binap catalyzed hydrogenation of 1a-b proceed dominantly via the β-diketone mode.A convenient asymmetric synthesis of hydroxylactone 3c and unsaturated lactone 5c was presented.Key words: 3,5-dioxoester; Ru-binap catalyst; asymmetric hydrogenation; asymmetric synthesis; lactone
- Shao, Liming,Kawano, Hiroyuki,Saburi, Masahiko,Uchida, Yasuzo
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p. 1997 - 2010
(2007/10/02)
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