- Diastereoselective Alkene Hydroesterification Enabling the Synthesis of Chiral Fused Bicyclic Lactones
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Palladium-catalysed diastereoselective hydroesterification of alkenes assisted by the coordinative hydroxyl group in the substrate afforded a variety of chiral γ-butyrolactones bearing two stereocenters. Employing the carbonylation-lactonization products as the key intermediates, the route from the alkenes with single chiral center to chiral THF-fused bicyclic γ-lactones containing three stereocenters was developed.
- Shi, Zhanglin,Shen, Chaoren,Dong, Kaiwu
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supporting information
p. 18039 - 18042
(2021/11/16)
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- Stereoselective total synthesis of (?)-galantinic acid and 1-deoxy-5-hydroxysphingolipids via prins cyclization
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The stereoselective total synthesis of (?)-galantinic acid 1 and 1-deoxy-5-hydroxysphingolipids 4 is described via Prins cyclization protocol followed by reductive ring opening sequence of substituted pyrenol derivative 6. The target molecules were synthesized using a common synthetic intermediate epoxide 5. Besides, we also proposed synthetic pathways to achieve other structural analogues using common intermediates.
- Rahman, Md. Ataur,Haque, Ashanul,Yadav, Jhillu Singh
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- A Novel Agonist of the Type 1 Lysophosphatidic Acid Receptor (LPA1), UCM-05194, Shows Efficacy in Neuropathic Pain Amelioration
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Neuropathic pain (NP) is a complex chronic pain state with a prevalence of almost 10% in the general population. Pharmacological options for NP are limited and weakly effective, so there is a need to develop more efficacious NP attenuating drugs. Activation of the type 1 lysophosphatidic acid (LPA1) receptor is a crucial factor in the initiation of NP. Hence, it is conceivable that a functional antagonism strategy could lead to NP mitigation. Here we describe a new series of LPA1 agonists among which derivative (S)-17 (UCM-05194) stands out as the most potent and selective LPA1 receptor agonist described so far (Emax = 118%, EC50 = 0.24 μM, KD = 19.6 nM; inactive at autotaxin and LPA2-6 receptors). This compound induces characteristic LPA1-mediated cellular effects and prompts the internalization of the receptor leading to its functional inactivation in primary sensory neurons and to an efficacious attenuation of the pain perception in an in vivo model of NP.
- González-Gil, Inés,Zian, Debora,Vázquez-Villa, Henar,Hernández-Torres, Gloria,Martínez, R. Fernando,Khiar-Fernández, Nora,Rivera, Richard,Kihara, Yasuyuki,Devesa, Isabel,Mathivanan, Sakthikumar,Del Valle, Cristina Rosell,Zambrana-Infantes, Emma,Puigdomenech, María,Cincilla, Giovanni,Sanchez-Martinez, Melchor,Rodríguez De Fonseca, Fernando,Ferrer-Montiel, Antonio V.,Chun, Jerold,López-Vales, Rubén,López-Rodríguez, María L.,Ortega-Gutiérrez, Silvia
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supporting information
p. 2372 - 2390
(2020/01/02)
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- Chiral Bifunctional Metalloporphyrin Catalysts for Kinetic Resolution of Epoxides with Carbon Dioxide
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Chiral binaphthyl-strapped Zn(II) porphyrins with triazolium halide units were synthesized as bifunctional catalysts for kinetic resolution of epoxides with CO2. Several catalysts were screened by changing the linker length and nucleophilic counteranions, and the optimized catalyst accelerated the enantioselective reaction at ambient temperature to produce optically active cyclic carbonates and epoxides.
- Maeda, Chihiro,Mitsuzane, Mayato,Ema, Tadashi
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supporting information
p. 1853 - 1856
(2019/03/11)
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- Improving the activity and enantioselectivity of PvEH1, a Phaseolus vulgaris epoxide hydrolase, for o-methylphenyl glycidyl ether by multiple site-directed mutagenesis on the basis of rational design
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Substrate spectrum assay exhibited that PvEH1, which is an epoxide hydrolase from P. vulgaris, had the highest specific activity and enantiomeric ratio (E) for racemic o-methylphenyl glycidyl ether (rac-1) among tested aryl glycidyl ethers (1–5). To produce (R)-1 via kinetic resolution of rac-1 efficiently, the catalytic properties of PvEH1 were further improved on the basis of rational design. Firstly, the seven single-site variants of PvEH1-encoding gene (pveh1) were PCR-amplified as designed, and expressed in E. coli BL21(DE3). Among all expressed single-site mutants, PvEH1L105I and PvEH1V106I had the highest specific activities of 17.6 and 16.4 U/mg protein, respectively, while PvEH1L196D had an enhanced E value of 9.2. Secondly, to combine their respective merits, one triple-site variant, pveh1L105I/V106I/L196D, was also amplified, and expressed. The specific activity, E value, and catalytic efficiency of PvEH1L105I/V106I/L196D were 23.1 U/mg, 10.9, and 6.65 mM?1 s?1, respectively, which were 2.0-, 1.8- and 2.4-fold higher than those of wild-type PvEH1. The source of PvEH1L105I/V106I/L196D with enhanced E value for rac-1 was preliminarily analyzed by molecular docking simulation. Finally, the scale-up kinetic resolution of 100 mM rac-1 was conducted using 5 mg wet cells/mL E. coli/pveh1L105I/V106I/L196D at 25 °C for 1.5 h, producing (R)-1 with 95.0% ees, 32.1% yield and 3.52 g/L/h space-time yield.
- Li, Chuang,Kan, Ting-Ting,Hu, Die,Wang, Ting-Ting,Su, Yong-Jun,Zhang, Chen,Cheng, Jian-Qing,Wu, Min-Chen
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- Asymmetric Hydrolytic and Aminolytic Kinetic Resolution of Racemic Epoxides using Recyclable Macrocyclic Chiral Cobalt(III) Salen Complexes
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New chiral macrocyclic cobalt(III) salen complexes were synthesized and used as catalyst for the asymmetric kinetic resolution (AKR) of terminal epoxides and glycidyl ethers with aromatic/aliphatic amines and water as nucleophiles. This is the first occasion where a Co(III) salen complex demonstrated its ability to catalyze AKR as well as hydrolytic kinetic resolution (HKR) reactions. Excellent enantiomeric excesses of the epoxides, the corresponding amino alcohols and diols (upto 99%) with quantitative yields were achieved by using the chiral Co(III) salen complexes in dichloromethane at room temperature. This protocol was further extended for the synthesis of two important drug molecules, i.e., (S)-propranolol and (R)-naftopidil. The catalytic system was also explored for the synthesis of chirally pure diols and chiral cyclic carbonates using carbon dioxide as a greener renewable C1 source. The catalyst was recycled for upto 5 catalytic cycles with retention of enantioselectivity. (Figure presented.).
- Tak, Rajkumar,Kumar, Manish,Menapara, Tusharkumar,Gupta, Naveen,Kureshy, Rukhsana I.,Khan, Noor-ul H.,Suresh
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supporting information
p. 3990 - 4001
(2017/11/22)
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- Effect of Partially Fluorinated N-Alkyl-Substituted Piperidine-2-carboxamides on Pharmacologically Relevant Properties
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The modulation of pharmacologically relevant properties of N-alkyl-piperidine-2-carboxamides was studied by selective introduction of 1–3 fluorine atoms into the n-propyl and n-butyl side chains of the local anesthetics ropivacaine and levobupivacaine. The basicity modulation by nearby fluorine substituents is essentially additive and exhibits an exponential attenuation as a function of topological distance between fluorine and the basic center. The intrinsic lipophilicity of the neutral piperidine derivatives displays the characteristic response noted for partially fluorinated alkyl groups attached to neutral heteroaryl systems. However, basicity decrease by nearby fluorine substituents affects lipophilicities at neutral pH, so that all partially fluorinated derivatives are of similar or higher lipophilicity than their non-fluorinated parents. Aqueous solubilities were found to correlate inversely with lipophilicity with a significant contribution from crystal packing energies, as indicated by variations in melting point temperatures. All fluorinated derivatives were found to be somewhat more readily oxidized in human liver microsomes, the rates of degradation correlating with increasing lipophilicity. Because the piperidine-2-carboxamide core is chiral, pairs with enantiomeric N-alkyl groups are diastereomeric. While little response to such stereoisomerism was observed for basicity or lipophilicity, more pronounced variations were observed for melting point temperatures and oxidative degradation.
- Vorberg, Raffael,Trapp, Nils,Zimmerli, Daniel,Wagner, Bj?rn,Fischer, Holger,Kratochwil, Nicole A.,Kansy, Manfred,Carreira, Erick M.,Müller, Klaus
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p. 2216 - 2239
(2016/10/19)
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- Substrate stereocontrol in bromine-induced intermolecular cyclization: Asymmetric synthesis of pitavastatin calcium
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A novel approach to synthesize pitavastatin calcium (1), an effective HMG-CoA reductase inhibitor, based on readily available and attractively functionalized (R)-3-chloro-1,2-propanediol is reported. This work highlights an intermolecular diastereoselective bromine-induced cyclization of homoallylic carbonate to meet stereochemical challenges in the synthesis of statins. An efficient route to a new triphenylphosphonium tetrafluoroborate salt of a quinoline core is also presented.
- Chen, Weiqi,Xiong, Fangjun,Liu, Qian,Xu, Lingjun,Wu, Yan,Chen, Fener
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p. 4730 - 4737
(2015/07/27)
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- A new enantioselective synthesis of (S)-2-ethoxy-3-(4-hydroxyphenyl) propanoic acid esters (EEHP and IEHP), useful pharmaceutical intermediates of PPAR agonists
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A new enantioselective synthetic route to the title compounds has been developed in a simple and practical way with high enantiopurity using commercially available starting material.
- Mujahid,Kunte,Muthukrishnan
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supporting information
p. 3223 - 3226
(2014/06/09)
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- Asymmetric hydrolytic kinetic resolution with recyclable polymeric Co(iii)-salen complexes: A practical strategy in the preparation of (S)-metoprolol, (S)-toliprolol and (S)-alprenolol: Computational rationale for enantioselectivity
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A series of chiral polymeric Co(iii)-salen complexes based on a number of achiral and chiral linkers were synthesized and their catalytic performances were assessed in the asymmetric hydrolytic kinetic resolution of terminal epoxides. The effects of the linker were judiciously studied and it was found that in the case of the chiral BINOL-based polymeric salen complex 1, there was an enrichment in catalyst reactivity and enantioselectivity of the unreacted epoxide, particularly in the case of short as well as long chain aliphatic epoxides. Good isolated yields of the unreacted epoxide (up to 46% compared to 50% theoretical yield) along with high enantioselectivity (up to 99%) were obtained in most cases using catalyst 1. Further studies showed that catalyst 1 could retain its catalytic activity for six cycles under the present reaction conditions without any significant loss in activity or enantioselectivity. To show the practical applicability of the above synthesized catalyst we have synthesised some potent chiral β-blockers in moderate yield and high enantioselectivity using complex 1. The DFT (M06-L/6-31+G??//ONIOM(B3LYP/6-31G?:STO-3G)) calculations revealed that the chiral BINOL linker influences the enantioselectivity achieved with Co(iii)-salen complexes. Further, the transition state calculations show that the R-BINOL linker with the (S,S)-Co(iii)-salen complex is energetically preferred over the corresponding S-BINOL linker with the (S,S)-Co(iii)-salen complex for the HKR of 1,2-epoxyhexane. The role of non-covalent C-H?π interactions and steric effects has been discussed to control the HKR reaction of 1,2-epoxyhexane.
- Roy, Tamal,Barik, Sunirmal,Kumar, Manish,Kureshy, Rukhsana I.,Ganguly, Bishwajit,Khan, Noor-Ul H.,Abdi, Sayed H. R.,Bajaj, Hari C.
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p. 3899 - 3908
(2015/02/19)
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- A novel enantioselective epoxide hydrolase from Agromyces mediolanus ZJB120203: Cloning, characterization and application
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A new strain Agromyces mediolanus ZJB120203, capable of enantioselective epoxide hydrolase (EH) activity was isolated employing a newly established colorimetric screening and chiral GC analysis method. The partial nucleotide sequence of an epoxide hydrolase (AmEH) gene from A. mediolanus ZJB120203 was obtained by PCR using degenerate primers designed based on the conserved domains of EHs. Subsequently, an open reading frame containing 1167 bp and encoding 388 amino acids polypeptide were identified. Expression of AmEH was carried out in Escherichia coli and purification was performed by Nickel-affinity chromatography. The purified AmEH had a molecular weight of 43 kDa and showed its optimum pH and temperature at 8.0 and 35 C, respectively. Moreover, this AmEH showed broad substrates specificity toward epoxides. In this study, it is demonstrated that the AmEH could unusually catalyze the hydrolysis of (R)-ECH to produce enantiopure (S)-ECH. Enantiopure (S)-ECH could be obtained with enantiomeric excess (ee) of >99% and yield of 21.5% from 64 mM (R,S)-ECH. It is indicated that AmEH from A. mediolanus is an attractive biocatalyst for the efficient preparation of optically active ECH.
- Xue, Feng,Liu, Zhi-Qiang,Zou, Shu-Ping,Wan, Nan-Wei,Zhu, Wen-Yuan,Zhu, Qing,Zheng, Yu-Guo
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p. 409 - 417
(2014/04/03)
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- Inhibition of quorum sensing and biofilm formation in Vibrio harveyi by 4-fluoro-DPD; A novel potent inhibitor of AI-2 signalling
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(S)-4,5-Dihydroxypentane-2,3-dione [(S)-DPD, (1)] is a precursor for AI-2, a quorum sensing signalling molecule for inter- and intra-species bacterial communication. The synthesis of its fluoro-analogue, 4-fluoro-5-hydroxypentane- 2,3-dione (2) is reported. An intermediate in this route also enables a new, shorter synthesis of the native (S)-DPD. 4-Fluoro-DPD (2) completely inhibited bioluminescence and bacterial growth of Vibrio harveyi BB170 strain at 12.5 μM and 100 μM, respectively.
- Kadirvel, Manikandan,Fanimarvasti, Fariba,Forbes, Sarah,McBain, Andrew,Gardiner, John M.,Brown, Gavin D.,Freeman, Sally
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supporting information
p. 5000 - 5002
(2014/05/06)
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- Asymmetric aminolytic kinetic resolution of racemic epoxides using recyclable chiral polymeric Co(III)-salen complexes: A protocol for total utilization of racemic epoxide in the synthesis of (R)-naftopidil and (S)-propranolol
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Chiral polymeric Co(III) salen complexes with chiral ((R)/(S)-BINOL, diethyl tartrate) and achiral (piperazine and trigol) linkers with varying stereogenic centers were synthesized for the first time and used as catalysts for aminolytic kinetic resolution (AKR) of a variety of terminal epoxides and glycidyl ethers to get enantio-pure epoxides (ee, 99%) and N-protected β-amino alcohols (ee, 99%) with quantitative yield in 16 h at RT under optimized reaction conditions. This protocol was also used for the synthesis of two enantiomerically pure drug molecules (R)-Naftopidil (α1- blocker) and (S)-Propranolol (β-blocker) as a key step via AKR of single racemic naphthylglycidyl ether with Boc-protected isoproylamine with 100% epoxide utilization at 1 g level. The catalyst 1 was successfully recycled for a number of times.
- Kumar, Manish,Kureshy, Rukhsana I.,Shah, Arpan K.,Das, Anjan,Khan, Noor-Ul H.,Abdi, Sayed H. R.,Bajaj, Hari C.
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p. 9076 - 9084
(2013/10/08)
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- First total synthesis of Debilisone C
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Total synthesis of Debilisone C, a lactone containing conjugated endiyne has been achieved. The adopted strategy involves the stereoselective construction of the five membered lactone ring and the C20 endiyne chain followed by regioselective coupling of both the parts. The lactone was obtained from the oxidative cleavage of the hydroxy olefin which was derived from the benzyl protected S-epichlorohydrine by regioselective epoxide opening with allyl trimethyl silane in presence of a Lewis acid at -78 °C. Takai olefination, Pd0/Ag1 catalyzed cross-coupling reaction and selective substitution of trimethylsilyl groups were successfully utilized to establish the C20 polyyne chain. The final coupling of both the parts have been carried out by alkyl coupling using LDA in THF-DMPU (1 : 1).
- Saikia, Bishwajit,Joymati Devi, Thongam,Barua, Nabin C.
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p. 905 - 913
(2013/03/14)
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- Enantioselective ring-opening reaction of epoxides with MeOH catalyzed by homochiral metal-organic framework
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Two new copper metal-organic frameworks containing 2,2′-dihydroxy-1, 1′-binaphthalene-5,5′-dicarboxylic acid (5,5′-H 2BDA) and 2,2′-dihydroxy-1,1′-binaphthalene-4,4′- dicarboxylic acid (4,4′-H2BDA) have been prepared. X-ray structure determination of [Cu2(5,5′-BDA)2(H 2O)2]·MeOH·2H2O (MOF-1) and [Cu2(4,4′-BDA)2(H2O)2] ·4H2O (MOF-2) revealed similar 2D sheet structures, containing square-grid coordination networks, but differences in the stacking motif. The desolvated MOF-1 and -2 were used as Lewis acid catalysts in the asymmetric ring-opening reaction of epoxides with MeOH.
- Tanaka, Koichi,Otani, Ken-Ichi,Murase, Takanori,Nishihote, Shyota,Urbanczyk-Lipkowska, Zofia
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experimental part
p. 709 - 714
(2012/08/08)
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- Stereoselective synthesis of tetrahydropyrans through tandem and organocatalytic oxa-Michael reactions: Synthesis of the tetrahydropyran cores of ent-(+)-sorangicin A
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Tandem and organocatalytic oxa-Michael reactions of α,β- unsaturated aldehydes were explored for the stereoselective synthesis of structurally complex tetrahydropyrans. Thestereoselective synthesis of 2,6-trans-tetrahydropyrans, which are thermodynamically unfavorable, was accomplished through a reagent-controlled, organocatalytic oxa-Michael reaction. A temperature-dependent configurational switch allowed the preparation of both 2,3-trans-2,6-trans-and 2,3-cis-2,6-cis-tetrahydropyrans from a common substrate. This switch was then used to synthesize the precursors of the C21-C29 and C30-C37 fragments of ent-(+)-sorangicin A. The tandem and organocatalytic oxa-Michael reactions of α,β-unsaturated aldehydes were explored and applied to the stereoselective synthesis of structurally complex tetrahydropyrans. Copyright
- Lee, Kiyoun,Kim, Hyoungsu,Hong, Jiyong
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scheme or table
p. 1025 - 1032
(2012/03/27)
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- An unusual (R)-selective epoxide hydrolase with high activity for facile preparation of enantiopure glycidyl ethers
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A novel epoxide hydrolase (BMEH) with unusual (R)-enantioselectivity and very high activity was cloned from Bacillus megaterium ECU1001. Highest enantioselectivities (E>200) were achieved in the bioresolution of ortho-substituted phenyl glycidyl ethers and para-nitrostyrene oxide. Worthy of note is that the substrate structure remarkably affected the enantioselectivities of the enzyme, as a reversed (S)-enantiopreference was unexpectedly observed for the ortho-nitrophenyl glycidyl ether. As a proof-of-concept, five enantiopure epoxides (>99% ee) were obtained in high yields, and a gram-scale preparation of (S)-ortho-methylphenyl glycidyl ether was then successfully performed within a few hours, indicating that BMEH is an attractive biocatalyst for the efficient preparation of optically active epoxides. Copyright
- Zhao, Jing,Chu, Yan-Yan,Li, Ai-Tao,Ju, Xin,Kong, Xu-Dong,Pan, Jiang,Tang, Yun,Xu, Jian-He
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experimental part
p. 1510 - 1518
(2011/08/03)
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- First asymmetric synthesis of the antiepileptic drug Lacosamide (Vimpat) based on a hydrolytic kinetic resolution strategy
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An efficient asymmetric synthesis of the new antiepileptic drug, Lacosamide is described in high enantiopurity (>98% ee), using Jacobsen's hydrolytic kinetic resolution strategy as a key step.
- Muthukrishnan,Mujahid,Sasikumar,Mujumdar
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experimental part
p. 1353 - 1357
(2011/11/29)
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- Olefin metathesis as a tool for multinuclear Co(III)salen catalyst construction: Access to cooperative catalysts
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The construction of novel (macrocyclic) multinuclear Co(iii)salen catalysts is reported. Olefin metathesis has been used as a key construction tool for the multimetallic structures starting from versatile allyl-substituted salen scaffolds. The Co(iii) complexes were tested in the hydrolytic kinetic resolution of (rac)-1,2-epoxyhexane and epoxide ring opening reactions using methanol as the nucleophile. The preliminary results suggest a cooperative mode of catalysis in the case of bis-Co(iii)salen macrocycle 10. The Royal Society of Chemistry.
- Haak, Robert M.,Martinez Belmonte, Marta,Escudero-Adan, Eduardo C.,Benet-Buchholz, Jordi,Kleij, Arjan W.
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experimental part
p. 593 - 602
(2010/04/04)
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- Bacillus alcalophilus MTCC10234 catalyzed enantioselective kinetic resolution of aryl glycidyl ethers
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The phenyl glycidyl ether derivatives have been kinetically resolved with the growing cells of Bacillus alcalophilus MTCC10234 yielding (S)-epoxides with up to >99% ee and (R)-diols with up to 89% ee. The enantiomeric ratio (E) of up to 67 has been obtained for biohydrolysis process. The effect of different substituents of phenyl glycidyl ether on the biocatalytic efficiency of B. alcalophilus MTCC10234 showed preference for methyl- and chloro-substituted aryl glycidyl ether derivatives whereas nitro-derivatives were transformed at a slower rate. 2,6-Dimethylphenyl glycidyl ether which contains a bulky aryl group having methyl group on both the ortho positions was resolved with an E=39.
- Bala, Neeraj,Chimni, Swapandeep Singh,Saini, Harvinder Singh,Chadha, Bhupinder Singh
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experimental part
p. 128 - 134
(2010/10/04)
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- The scope and limitation of the regio- and enantioselective hydrolysis of aliphatic epoxides using Bacillus subtilis epoxide hydrolase, and exploration toward chirally differentiated tris(hydroxymethyl)methanol
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The substrate specificity of an engineered Bacillus subtilis epoxide hydrolase, which so far had shown high activity and enantioselectivity with 1-benzyloxymethyl-1-methyloxirane, has been studied by altering the methyl substituent into hydrogen, oxygen-containing functionalities, and unsaturated homologs. High enantioselectivity (E = 44) was observed with 1-benzyloxymethyl-1-vinyloxirane with a proper catalytic activity. The elaboration of the reaction conditions and work-up procedures enabled a preparative-scale kinetic resolution, to give (R)-2-benzyloxymethyl-3-butene-1, 2-diol and its antipodal (R)-epoxide in high ees.
- Shimizu, Ken-Ichi,Sakamoto, Maki,Hamada, Manabu,Higashi, Toshinori,Sugai, Takeshi,Shoji, Mitsuru
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experimental part
p. 2043 - 2049
(2010/10/19)
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- A concise stereoselective formal total synthesis of the cytotoxic macrolide (+)-Neopeltolide via Prins cyclization
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A convergent and highly stereoselective formal total synthesis of the naturally occurring, cytotoxic 14-membered macrolide neopeltolide has been achieved via two Prins cyclizations.
- Yadav, Jhillu Singh,Krishana, Gunda Gopala,Kumar, Satya Narayana
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body text
p. 480 - 487
(2010/03/03)
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- Algal pheromone biosynthesis: Stereochemical analysis and mechanistic implications in gametes of ectocarpus siliculosus
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During sexual reproduction, female gametes or eggs of brown algae release pheromones to attract their male mating partners. The biologically active compounds comprise linear or alicyclic unsaturated hydrocarbons derived from the aliphatic terminus of C20 polyunsaturated fatty acids (PUFAs) by oxidative cleavage. The current study addresses the stereochemical course of the pheromone biosynthesis using female gametes of the marine brown alga E. siliculosus and chiral deuterium-labeled arachidonic acids. The biosynthetic sequence is likely to proceed via an intermediary 9-hydroperoxyarachidonic acid, which is cleaved with loss of the C(16)-HR into the C 11-hydrocarbon dictyopterene C and 9-oxonona-(5Z,7E)-dienoic acid.
- Rui, Fabio,Boland, Wilhelm
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supporting information; scheme or table
p. 3958 - 3964
(2010/08/22)
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- Differential interaction of an AmB Analogue and ergosterol in enantiomeric membranes
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An amphotericin B derivative exhibits differential interaction with vesicles formed from either natural (R)-or unnatural (S)-POPC and ergosterol. This implicates a close association between the polyene macrolide and the phospholipid bilayer and may account for its increased antifungal activity.
- Jeon, Ock-Youm,Carreira, Erick M.
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supporting information; experimental part
p. 1772 - 1775
(2010/09/07)
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- Highly efficient recyclable CoIII-salen complexes in the catalyzed asymmetric aminolytic kinetic resolution of aryloxy/terminal epoxides for the simultaneous production of N-protected 1,2-amino alcohols and the corresponding epoxides in high op
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Chiral CoIII-salen complexes 1-6 bearing different substituents at the 3,3′- and 5,5′-positions of the salen unit, namely H, tBu, morpholmomethyl, and piperidinomethyl, have been synthesized. These complexes were used as catalysts in an environ
- Kureshy, Rukhsana I.,Prathap, K. Jeya,Agrawal, Santosh,Kumar, Manish,Khan, Noor-Ul H.,Abdi, Sayed H. R.,Bajaj, Hari C.
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supporting information; experimental part
p. 2863 - 2871
(2009/09/29)
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- Ring-conformer effects of the cyclopropyl group: First use of trans-(2r,3r)-cyclopropanecarbaldehydes as electrophiles in diastereoselective baylisihillman reaction
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trans-(2R,3R)-Cyclopropanecarbaldehydes are used as novel electrophiles in the Baylis-Hillman reaction to afford adducts in good yields (75-85%) and diastereoselectivities (60-90%).
- Krishna, Palakodety Radha,Kishore,Reddy, P. Srinivas
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scheme or table
p. 2605 - 2608
(2010/03/03)
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- Stereoselective routes for the total synthesis of (+)-cryptocarya diacetate
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A stereoselective total synthesis of (+)-cryptocarya diacetate (1) was achieved by two different routes (Schemes 2 and 3). The sequences involve LiAlH4/LiI reduction, ring-closing metathesis, Prins cyclization, Wacker oxidation, and Wittig olefination reactions as key steps.
- Sabitha, Gowravaram,Reddy, Nandyala M.,Prasad, Muddala N.,Yadav, Jhillu S.
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experimental part
p. 967 - 976
(2009/08/15)
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- Stereoselective synthesis of 10,14-dimethyloctadec-1-ene, 5,9-dimethyloctadecane, and 5,9-dimethylheptadecane, the sex pheromones of female apple leafminer
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The stereoselective synthesis of (10R,14R)-10,14-dimethyloctadec-1-ene (1), (5R,9R)-5,9-dimethyloctadecane (2), and (5R,9R)-5,9-dimethylheptadecane (3) the sex pheromone components of female apple leafminer was accomplished by reductive elimination tosyl and isonitrile groups of dialkylated tosylmethyl isonitrile. The key steps involved were dialkylation of TosMIC with 1-iodo 2-methyl alkanes, which were derived from Evan's alkylation of chiral auxiliary and subsequent reduction.
- Yadav, Jhillu S.,Gayathri, Kamakolanu Uma,Thrimurtulu, Neetipalli,Prasad, Attaluri R.
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scheme or table
p. 3536 - 3544
(2009/09/05)
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- Preparation of optically active 1-O-alkyl-3-O-arylsulfonyl-sn-grycerol derivatives: Substrate engineering in enzyme-mediated enantioselective hydrolysis
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Lipase PS catalyzes the enantioselective hydrolysis of various 2-acetyl compounds of the 1-O-alkyl-3-O-arylsulfonyl-sn-glycerol derivatives to afford the corresponding optically active compounds. Changing the structure of the 1-O-alkyl and 3-O-arylsulfonyl groups affects both the reactivity and enantioselectivity. Finally, the E value of the reaction for 2-acetyl-3-O-3,5-dimethylbenzenesulfonyl-1-O-4-methoxybenzyl-sn-glycerol is greater than 200. Georg Thieme Verlag Stuttgart.
- Shimada, Yasutaka,Sato, Hiroshi,Mochizuki, Sachiyo,Matsumoto, Kazutsugu
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scheme or table
p. 2981 - 2984
(2009/10/17)
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- A concise synthesis of protected (2S,4R)-4-hydroxyornithine
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A short synthesis of the nonproteinogenic amino acid, (2S,4R)-4-hydroxyornithine is described. Starting from racemic benzyl glycidol, the scaffold of the target compound was constructed in high enantio- and diastereoselectivity using Jacobsen's hydrolytic kinetic resolution (HKR) and regioselective opening of an epoxide as key steps.
- Pandey, Satyendra Kumar,Pandey, Menaka,Kumar, Pradeep
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p. 3297 - 3299
(2008/09/20)
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- NEW CHIRAL SALEN CATALYSTS AND METHODS FOR THE PREPARATION OF CHIRAL COMPOUNDS FROM RACEMIC EPOXIDES BY USING THEM
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The present invention relates to new chiral salen catalysts and the preparation method of chiral compounds from racemic epoxides using the same. More specifically, it relates to new chiral salen catalysts that have high catalytic activity due to new molecular structures and have no or little racemization of the generated target chiral compounds even after the reaction is completed and can be also reused without catalyst regeneration treatment, and its economical preparation method to mass manufacture chiral compounds of high optical purity, which can be used as raw materials for chiral food additives, chiral drugs, or chiral crop protection agents, etc., using the new chiral salen catalysts.
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Page/Page column 39; 40
(2009/01/24)
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- Solid-phase synthesis of [5.5]-spiroketals
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An efficient and reliable multi-step synthesis of 251 natural product-like [5.5]-spiroketals on solid supports has been developed. As central key step, a double intramolecular hetero-Michael (DIHMA) reaction to alkynones was applied. The sequence allows for introduction of numerous substituents on the scaffold and for variation of stereochemistry. [5.5]-Spiroketals bearing an additional ketone were obtained in high overall yields. Further diversification was achieved by reduction of the ketone and reductive amination using polymer-supported borohydride, Grignard reaction and conversion to oxime derivatives in the solution phase.
- Sommer, Stefan,Kuehn, Marc,Waldmann, Herbert
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supporting information; experimental part
p. 1736 - 1750
(2009/08/14)
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- Synthesis and biological evaluation of γ-aminophosphonates as potent, subtype-selective sphingosine 1-phosphate receptor agonists and antagonists
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The synthesis of N-arylamide phosphonates and related arylether and arylamine analogues provided potent, subtype-selective agonists and antagonists of the five known sphingosine 1-phosphate (S1P) receptors (S1P1-5). To this end, the syntheses of phosphoserine mimetics-selectively protected and optically active phosphonoserines-are described. In vitro binding assays showed that the implementation of phosphonates as phosphate mimetics provided compounds with similar receptor binding affinities as compared to their phosphate precursors. meta-substituted arylamide phosphonates were discovered to be antagonists of the S1P1 and S1P3 receptors. When administered to mice, an antagonist blocked the lymphopenia evoked by a S1P receptor agonist and caused capillary leakage in both lung and kidney.
- Foss Jr., Frank W.,Snyder, Ashley H.,Davis, Michael D.,Rouse, Michael,Okusa, Mark D.,Lynch, Kevin R.,Macdonald, Timothy L.
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p. 663 - 677
(2007/10/03)
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- Self-assembled nanoreactors as highly active catalysts in the hydrolytic kinetic resolution (HKR) of epoxides in water
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CoIII(salen) complexes have been immobilized on amphiphilic block copolymers, which self-assemble in water to give micellar aggregates with a hydrophobic Co(salen) core and a water-soluble shell (see picture). These aggregates were used to catalyze the hydrolytic kinetic resolution (HKR) of racemic aromatic epoxides over four consecutive cycles and gave the epoxides in up to 99 % ee. H2salen = N,N′-bis(salicylidene)ethylenediamine. (Chemical Equation Presented).
- Rossbach, Benjamin M.,Leopold, Kerstin,Weberskirch, Ralf
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p. 1309 - 1312
(2007/10/03)
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- Chemical variation of natural product-like scaffolds: Design and synthesis of spiroketal derivatives
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The design and synthesis of spiroketal structures and their chemical modification, leading to a collection of new small molecules for biological evaluation as orally-bioavailable lead compounds is described. Both [6,5]- and [6,6]-membered ring spiroketal units have been prepared in a stereochemically-varying fashion starting from commercially available (R)- or (S)-glycidol, in ten, eleven and twelve linear steps, in overall yields of 45, 40 and 20%, respectively. Further elaboration according to Lipinski's guidelines has given a collection of structurally-diverse, new spiroketal derivatives in high yields and with high purity. The Royal Society of Chemistry 2006.
- Zinzalla, Giovanna,Milroy, Lech-Gustav,Ley, Steven V.
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p. 1977 - 2002
(2008/02/04)
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- Synthesis of the bis-spiroacetal moiety of the shellfish toxins spirolides B and D using an iterative oxidative radical cyclization strategy
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The enantioselective synthesis of the bis-spiroacetal fragment of the shellfish toxins, spirolides B 1 and D 2, is reported. The carbon framework was constructed via a Barbier reaction of dihydropyran 10 with aldehyde 11, followed by two oxidative radical cyclizations to construct the bis-spiroacetal ring system. A silyl-modified Prins cyclization and enantioselective crotylation successfully installed the stereocenters in the cyclization precursor 21. The initial unsaturated bis-spiroacetals 9a-d underwent equilibration during epoxidation to trans-epoxide 24 that was converted to tertiary alcohol 7. The Royal Society of Chemistry 2006.
- Meilert, Kai,Brimble, Margaret A.
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p. 2184 - 2192
(2008/02/05)
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- First total synthesis of 7(S),17(S)-Resolvin D5, a potent anti-inflammatory docosanoid
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The first total synthesis of 7(S),17(S)-Resolvin D5, a lipid mediator derived from docosahexaenoic acid, has been achieved. The chiral centers were generated via a Co-salen hydrolytic kinetic resolution of a terminal epoxide with >99% ee. Key steps include Takai olefination, Pd0/Cu I coupling and simultaneous deprotection and ester cleavage with lipase from Candida rugosa.
- Rodríguez, Ana R.,Spur, Bernd W.
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p. 3623 - 3627
(2007/10/03)
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- An expeditious synthesis of 1-substituted and cyclic taurines
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A series of 1-substituted taurines, including optically active taurines, were synthesized expeditiously from epoxides via episulfidation with potassium sulfocyanate, ring-opening with dibenzylamine, followed by oxidation with performic acid, and hydrogenolysis in the presence of palladium hydroxide on carbon powder. This method was also used for the synthesis of trans-cyclic taurines. Georg Thieme Verlag Stuttgart.
- Huang, Jiaxing,Wang, Fei,Du, Da-Ming,Xu, Jiaxi
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p. 2122 - 2128
(2007/10/03)
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- Mechanistic Investigation Leads to a Synthetic Improvement in the Hydrolytic Kinetic Resolution of Terminal Epoxides
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The mechanism of the hydrolytic kinetic resolution (HKR) of terminal epoxides was investigated by kinetic analysis using reaction calorimetry. The chiral (salen)Co-X complex (X = OAc, OTs, Cl) undergoes irreversible conversion to (salen)Co-OH during the course of the HKR and thus serves as both precatalyst and cocatalyst in a cooperative bimetallic catalytic mechanism. This insight led to the identification of more active catalysts for the HKR of synthetically useful terminal epoxides. Copyright
- Nielsen, Lars P. C.,Stevenson, Christian P.,Blackmond, Donna G.,Jacobsen, Eric N.
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p. 1360 - 1362
(2007/10/03)
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- Highly selective hydrolytic kinetic resolution of terminal epoxides catalyzed by chiral (salen)CoIII complexes. Practical synthesis of enantioenriched terminal epoxides and 1,2-diols
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The hydrolytic kinetic resolution (HKR) of terminal epoxides catalyzed by chiral (salen)CoIII complex 1·OAc affords both recovered unreacted epoxide and 1,2-diol product in highly enantioenriched form. As such, the HKR provides general access to useful, highly enantioenriched chiral building blocks that are otherwise difficult to access, from inexpensive racemic materials. The reaction has several appealing features from a practical standpoint, including the use of H2O as a reactant and low loadings (0.2-2.0 mol %) of a recyclable, commercially available catalyst. In addition, the HKR displays extraordinary scope, as a wide assortment of sterically and electronically varied epoxides can be resolved to ≥ 99% ee. The corresponding 1,2-diols were produced in good-to-high enantiomeric excess using 0.45 equiv of H2O. Useful and general protocols are provided for the isolation of highly enantioenriched epoxides and diols, as well as for catalyst recovery and recycling. Selectivity factors (krel) were determined for the HKR reactions by measuring the product ee at ca. 20% conversion. In nearly all cases, krel values for the HKR exceed 50, and in several cases are well in excess of 200.
- Schaus, Scott E.,Brandes, Bridget D.,Larrow, Jay F.,Tokunaga, Makoto,Hansen, Karl B.,Gould, Alexandra E.,Furrow, Michael E.,Jacobsen, Eric N.
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p. 1307 - 1315
(2007/10/03)
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- A practical synthesis of (R)- and (S)-benzylglycidols by hydrolytic kinetic resolution
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A new synthetic approach to both the enantiomers of O-benzylglycidol, involving hydrolytic kinetic resolution, has been described.
- Gurjar,Sarma,Sadalapure,Adhikari
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p. 1424 - 1424
(2007/10/03)
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- Studies directed towards the total synthesis of (+)-himbacine
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A convergent strategy towards himbacine (1), involving a Julia coupling between aldehyde 5 and sulfone 6 was found to be ineffective. The aldehyde 5 was synthesized via the thermal intramolecular cycloaddition of 4 with preferred formation of the endo-adduct. The Diels-Alder precursor 4 was obtained from butenolide 7, the result of a single-step condensation between the enoate derived from the (Z)-conjugated olefin 12 and 2-acetoxypropanal. In the context of the synthesis of sulfone 6 Taber's method for the synthesis of 2,6-trans-disubstituted piperidine was adapted towards a large scale synthesis of 49, a useful intermediate for the synthesis in this area.
- Hofman, Sven,De Baecke, Govert,Kenda, Beno?t,De Clercq, Pierre J.
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p. 479 - 489
(2007/10/03)
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- Total synthesis of (-)-galbonolide B and the determination of its absolute stereochemistry
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Through a trans-lactonization reaction, galbonolide B (1) was converted to 3 with the chiral secondary alcohol at C13 exposed for derivatization. Two independent methods were employed to determine the absolute chirality at C13. Both of these methods established S chirality at C13. Since the relative stereochemistry of galbonolide B had been determined from the X-ray structure, the absolute stereochemistry of galbonolide B was therefore formally established to be structure 1, which contradicted earlier speculations in the literature. A total synthesis of galbonolide B has been completed. A highly selective method was developed for the assembly of the peculiar diene unit using Martin's sulfurane reagent for the dehydration of the preceding tertiary alcohol 20. The chiral center at C4 was installed by 'contra-steric' enolate chemistry. A novel macro-Dieckmann cyclization was employed to generate the macrocycle. The desired configuration at C2 was obtained from the kinetic protonation of the corresponding enolate. Finally, a seldom used protecting group, 2,4,6-trimethylbenzylidene acetal, was employed for the glycol unit. It exhibited extremely facile hydrolysis under mildly acidic conditions without causing any decomposition of synthetic intermediates.
- Tse, Bruno
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p. 7094 - 7100
(2007/10/03)
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- Co-Solvent Enhancement of Enantioselectivity in Lipase-Catalysed Hydrolysis of Racemic Esters. A Process for Production of Homochiral C-3 Building Blocks using Lipase B from Candida antarctica
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Lipase-catalysed hydrolysis of butanoates of 3-methoxy-1-(phenylmethoxy)-2-propanol and 3-chloro-1-(phenylmethoxy)-2-propanol with various lipases gave low enantioselectivity, E.By addition of water miscible organic cosolvents, in particular tert-butanol and acetone, the E-value was raised from 7 to 220 for the useful chloro derivative.This finding has led to proposal of a process for production of homochiral C-3 synthons such as both enantiomers of phenylmethyl glycidyl ether starting from racemic epichlorohydrin.NMR studies of lipase B from Candida antarctica showthat the conformation most likely is not changed upon addition of up to 50percent acetone.Nuclear Overhauser effects were observed upon irradiation of the phenyl protons of the substrate only in the presence of enzyme thus indicating an interaction between the two.
- Hansen, Trond Vidar,Waagen, Viggo,Partali, Vassilia,Anthonsen, Henrik W.,Anthonsen, Thorleif
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p. 499 - 504
(2007/10/02)
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- Enzymatic resolution of butanoic esters of 1-phenylmethyl and 1-[2-phenylethyl]ethers of 3-chloro-1,2-propanediol
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The enzymatic hydrolysis of butanoic esters of 1-phenylmethyl- and 1-[2-phenylethyl] ethers of 3-chloro-1,2-propanediol has been studied by using lipases. Highest enantiomeric ratio was obtained with PPL for the phenylmethyl ether and with Amano SAM II for the phenylethyl ether. The absolute configurations of the products was verified in two ways. Both the produced alcohols and the remaining esters were converted into the corresponding glycidyl ethers which also were synthesised in homochiral forms starting from (S)-epichlorohydrin. The produced alcohols and the remaining esters were prepared independently from (S)-epichlorohydrin.
- Partali,Waagen,Alvik,Anthonsen
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p. 961 - 968
(2007/10/02)
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- A FACILE SYNTHESIS OF (S)-O-BENZYLGLYCIDOL
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A facile synthesis of (S)-O-benzylglycidol has been developed starting from (R)-1-O-benzylglycerol by sequential monohalogenation and cyclization.
- Takano, Seiichi,Sugihara, Takumichi,Kamikubo, Takashi,Ogasawara, Kunio
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p. 1587 - 1591
(2007/10/02)
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