- Highly stereocontrolled reduction of 1,3-cyclopentanediones using oxazaborolidine -BH3
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Highly enantioselective reduction of 1,3-cyclopentanediones was conducted using an oxazaborolidine derived from L-threonine and a borane complex to give either 1,3-cyclopentanediols or 3-hydroxycyclopentanones in high enantiomeric purity by choosing appropriate reduction conditions. Copyright (C) 2000 Elsevier Science Ltd.
- Shimizu, Makoto,Yamada, Shunsuke,Fujita, Yoshifumi,Kobayashi, Fumiko
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- Desymmetric enantioselective reduction of cyclic 1,3-diketones catalyzed by a recyclable p-chiral phosphinamide organocatalyst
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The P-stereogenic phosphinamides are a structurally novel skeletal class which has not been investigated as chiral organocatalysts. However, chiral cyclic 3-hydroxy ketones are widely used as building blocks in the synthesis of natural products and bioactive compounds. However, general and practical methods for the synthesis of such chiral compounds remain underdeveloped. Herein, we demonstrate that the P-stereogenic phosphinamides are powerful organocatalysts for the desymmetric enantioselective reduction of cyclic 1,3-diketones, providing a useful method for the synthesis of chiral cyclic 3-hydroxy ketones. The protocol displays a broad substrate scope that is amenable to a series of cyclic 2,2-disubstituted five- and six-membered 1,3-diketones. The chiral cyclic 3-hydroxy ketone products bearing an all-carbon chiral quaternary center could be obtained with high enantioselectivities (up to 98% ee) and diastereoselectivities (up to 99:1 dr). Most importantly, the reactions could be practically performed on the gram scale and the catalysts could be reused without compromising the catalytic efficiency. Mechanistic studies revealed that an intermediate formed from P-stereogenic phosphinamide and catecholborane is the real catalytically active species. The results disclosed herein bode well for designing and developing other reactions using P-stereogenic phosphinamides as new organocatalysts.
- Qin, Xu-Long,Li, Ang,Han, Fu-She
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supporting information
p. 2994 - 3002
(2021/03/01)
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- Structure-Guided Directed Evolution of a Carbonyl Reductase Enables the Stereoselective Synthesis of (2 S,3 S)-2,2-Disubstituted-3-hydroxycyclopentanones via Desymmetric Reduction
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In this study, an engineered carbonyl reductase (M4) was obtained through structure-guided directed evolution of a carbonyl reductase (SSCR) from Sporobolomyces salmonicolor AKU4429. Mutant M4 showed 23.9-fold enhancement of enzyme activity toward the model substrate 2-methyl-2-benzyl-1,3-cyclopentanedione, affording the (2S,3S)-stereoisomer in >98percent ratio. This variant also showed excellent stereoselectivity toward most of the tested substrates, offering a valuable biocatalyst for the stereoselective reduction of these cyclic diketones to access the corresponding (2S,3S)-2,2-disubstituted-3-hydroxyketones.
- Li, Juan,Feng, Jinhui,Chen, Xi,Gong, Jingyao,Cui, Yunfeng,Zhang, Hongliu,Bu, Dandan,Wu, Qiaqing,Zhu, Dunming
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supporting information
p. 3444 - 3448
(2020/05/19)
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- Stereoselective Reduction of Prochiral Cyclic 1,3-Diketones Using Different Biocatalysts
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We have developed biocatalytic methods for the stereoselective reduction of cyclic prochiral 1,3-diketones for the production of optically active β-hydroxyketones and/or 1,3-diols. The recombinant ketoreductase KRED1-Pglu (formulated as purified catalyst)
- Contente, Martina Letizia,Dall’Oglio, Federica,Annunziata, Francesca,Molinari, Francesco,Rabuffetti, Marco,Romano, Diego,Tamborini, Lucia,Rother, D?rte,Pinto, Andrea
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p. 1176 - 1185
(2019/11/16)
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- Synthetic Studies on Enantioselective Total Synthesis of Cyathane Diterpenoids: Cyrneines A and B, Glaucopine C, and (+)-Allocyathin B2
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The details for the synthetic studies on enantioselective total synthesis of cyathane diterpenoids cyrneine A (1) and B (2), glaucopine C (3), and (+)-allocyathin B2 are presented. We established a mild Suzuki coupling for heavily substituted n
- Wu, Guo-Jie,Zhang, Yuan-He,Tan, Dong-Xing,He, Long,Cao, Bao-Chen,He, Yu-Peng,Han, Fu-She
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- A Total Synthesis of (-)-Hamigeran B and (-)-4-Bromohamigeran B
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A concise synthesis of (-)-hamigeran B and (-)-4-bromohamigeran B is presented. The key reactions include a Suzuki coupling of enol triflate 15 with arylboronic ester for efficient synthesis of the densely 1,2,3-trisubstituted cyclopentene 23, a coordinat
- Cao, Bao-Chen,Wu, Guo-Jie,Yu, Fang,He, Yu-Peng,Han, Fu-She
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p. 3687 - 3690
(2018/06/26)
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- Efforts toward rapid construction of the cortistatin A carbocyclic core via enyne-ene metathesis
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Our efforts toward the construction of the carbocylic core of cortistatin A via an enyne-ene metathesis are disclosed. Interestingly, an attempted S N2 inversion of a secondary mesylate in our five-membered D-ring piece gave a product with rete
- Baumgartner, Corinne,Ma, Sandy,Liu, Qi,Stoltz, Brian M.
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scheme or table
p. 2915 - 2917
(2010/09/06)
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- Preparation of all stereoisomers of 2-allyl-2-methyl-3-hydroxycyclopentanone by desymmetric processes based on a microbial oxidation and reduction system
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All stereoisomers of 2-allyl-3-hydroxy-2-methylcyclopentanones 2-5 were prepared in high conversion and in an optically pure form by microbial reduction and oxidation. The reduction of symmetric diketone 1 by Geotrichum candidum NBRC 4597 under anaerobic conditions gave 2 in 83% yield (98% conversion), >99% de, and >99% ee, whereas the reduction of 1 by G. candidum NBRC 5767 under aerobic conditions gave 3 in 75% yield (99% conversion), >99% de, and >99% ee. Oxidation of meso-diol 6 by G. candidum NBRC 5767 under aerobic conditions afforded 4 in 83% yield (99% conversion) and >99% ee, while oxidation of meso-diol 7 by Mucor heimalis IAM 6095 in the presence of cyclohexanone as a co-oxidant afforded 5 in 68% yield (75% conversion) and >99% ee.
- Fujii, Mikio,Takeuchi, Minoru,Akita, Hiroyuki,Nakamura, Kaoru
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scheme or table
p. 4941 - 4944
(2009/12/01)
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- Comparative reductive desymmetrization of 2,2-disubstituted-cycloalkane-1,3-diones
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Reductive desymmetrization of 2-methyl-2-substituted-cycloalkane-1,3-diones can be effected using either NaBH4 in DME or lithium tri-tert-butoxyaluminum hydride (LTBA) in THF at -60 °C. The former is a new approach that offers slightly greater
- Carr, Jeremy M.,Snowden, Timothy S.
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p. 2897 - 2905
(2008/09/20)
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- Enantioselective total synthesis of (+)-digitoxigenin
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An enantioselective total synthesis of (+)-digitoxigenin is described. This total synthesis is accomplished in a convergent manner using two chiral fragments prepared via the catalytic asymmetric intramolecular cyclopropanation and baker's yeast mediated reduction developed by us, respectively. This convergent synthesis would be useful for preparing some new derivatives of digitoxigenin for SAR studies and could be applied for the total synthesis of other cardenolides left unprepared.
- Honma, Masahiro,Nakada, Masahisa
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p. 1541 - 1544
(2008/02/03)
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- Diastereoselective reduction of β-keto carbonyl compounds by cultured plant cells
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The diastereoselective reduction of β-keto carbonyl compounds such as 2-benzamidomethyl-3-oxobutanoates and 2-methyl-2-(2-propenyl)cyclopentan-1,3- dione by cultured cells of higher plants was investigated. The reduction of the 2-benzamidomethyl-3-oxobuta
- Shimoda, Kei,Kubota, Naoji,Hamada, Hatsuyuki,Hamada, Hiroki
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p. 1541 - 1544
(2007/10/03)
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- General synthetic approach to bicyclo[9.3.0]tetradecenone: A versatile intermediate to clavulactone and clavirolides
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An efficient and stereoselective approach to the bicyclo[9.3.0] tetradecenone core structure of clavulactone starting from readily and abundantly available 2-methyl-1,3-cyclopentandione employing microbial desymmetrization and cyanohydrin alkylation as th
- Sun, Bingfeng,Xu, Xingxiang
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p. 8431 - 8434
(2007/10/03)
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- Asymmetric Microbial Reduction of Prochiral 2,2-Disubstituted Cycloalkanediones
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Asymmetric microbial reduction of a series of 2,2-disubstituted 1,3-cycloalkanediones with bakers' yeast was examined as an example of an enzyme-catalyzed distinction of a substrate containing two trigonal carbonyl centers with stereoheterotropic faces an
- Brooks, Dee W.,Mazdiyasni, Hormoz,Grothaus, Paul G.
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p. 3223 - 3232
(2007/10/02)
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- Chiral Cyclopentanoid Synthetic Intermediates via Asymmetric Microbial Reduction of Prochiral 2,2-Disubstituted Cyclopentanediones
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A prochiral distinction by microbial reduction of 2-propyl- (1), 2-allyl- (4), and 2-propynyl-2-methyl-1,3-cyclopentanedione (7) with bakers' yeast provides efficient access to several chiral cyclopentanoid synthetic intermediates.A short enantioselective
- Brooks, Dee W.,Grothaus, Paul G.,Irwin, William L.
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p. 2820 - 2821
(2007/10/02)
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- SYNTHETIC STUDIES OF TRICHOTHECENES, AN ENANTIOSELECTIVE SYNTHESIS OF A C-RING PRECURSOR OF ANGUIDINE
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An enantioselective synthesis of a cyclopentanoid C-ring precursor 19 of anguidine 3, a representative trichothecene with antitumor activity, from 2-allyl-2-methylcyclopentane-1,3-dione is described.
- Brooks, Dee W.,Grothaus, Paul G.,Palmer, James T.
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p. 4187 - 4190
(2007/10/02)
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