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Bondar OA, Moustafa GAI, Robertson TBR. Hyperpolarised [2- 13C]-pyruvate by 13C SABRE in an acetone/water mixture. Analyst 2024; 149:5668-5674. [PMID: 39485096 PMCID: PMC11529384 DOI: 10.1039/d4an01005a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2024] [Accepted: 10/08/2024] [Indexed: 11/03/2024]
Abstract
Signal Amplification By Reversible Exchange (SABRE) can provide strong signal enhancement (SE) to an array of molecules through reversible exchange of parahydrogen (pH2) derived hydrides and a suitable substrate coordinated to a transition metal. Among the substrates that can be used as a probe for hyperpolarised NMR and MRI, pyruvate has gained much attention. SABRE can hyperpolarise pyruvate in a low cost, fast, and reversible fashion that does not involve technologically demanding equipment. Most SABRE polarization studies have been done using methanol-d4 as a solvent, which is not suitable for in vivo application. The main goal of this work was to obtain hyperpolarized pyruvate in a solvent other than methanol which may open the door to further purification steps and enable a method to polarize pyruvate in water in future. This work demonstrates hyperpolarization of the [2-13C]pyruvate as well as [1-13C]pyruvate by SABRE in an acetone/water solvent system at room temperature as an alternative to methanol, which is commonly used. NMR signals are detected using a 1.1 T benchtop NMR spectrometer. In this work we have primarily focused on the study of [2-13C]pyruvate and investigated the effect of catalyst concentration, DMSO presence and water vs. acetone solvent concentration on the signal enhancement. The relaxation times for [2-13C]-pyruvate solutions are reported in the hope of informing the development of future purification methods.
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Maklad RM, Moustafa GAI, Aoyama H, Elgazar AA. Controlling (E/Z)-Stereoselectivity of -NHC=O Chlorination: Mechanism Principles for Wide Scope Applications. Chemistry 2024; 30:e202400785. [PMID: 38958609 DOI: 10.1002/chem.202400785] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2024] [Revised: 07/02/2024] [Accepted: 07/03/2024] [Indexed: 07/04/2024]
Abstract
Organic halogen compounds are cornerstones of applied chemical sciences. Halogen substitution is a smart molecular design strategy adopted to influence reactivity, membrane permeability and receptor interaction. Chiral bioreceptors may restrict the stereochemical requirements in the halo-ligand design. Straightforward (but expensive) catalyzed stereospecific halogenation has been reported. Historically, PCl5 served access to uncatalyzed stereoselective chlorination although the stereochemical outcomes were influenced by steric parameters. Nonetheless, stereochemical investigation of PCl5 reaction mechanism with carbamoyl (RCONHX) compounds has never been addressed. Herein, we provide the first comprehensive stereochemical mechanistic explanation outlining halogenation of carbamoyl compounds with PCl5; the key regioselectivity-limiting nitrilimine intermediate (8-Z.HCl); how substitution pattern influences regioselectivity; why oxadiazole byproduct (P1) is encountered; stereo-electronic factors influencing the hydrazonoyl chloride (P2) production; and discovery of two stereoselectivity-limiting parallel mechanisms (stepwise and concerted) of elimination of HCl and POCl3. DFT calculations, synthetic methodology optimization, X-ray evidence and experimental reaction kinetics study evidence all supported the suggested mechanism proposal (Scheme 2). Finally, we provide mechanism-inspired future recommendations for directing the reaction stereoselectivity toward elusive and stereochemically inaccessible (E)-bis-hydrazonoyl chlorides along with potentially pivotal applications of both (E/Z)-stereoisomers especially in medicinal chemistry and protein modification.
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Dagys L, Bengs C, Moustafa GAI, Levitt MH. Deuteron-Decoupled Singlet NMR in Low Magnetic Fields: Application to the Hyperpolarization of Succinic Acid. Chemphyschem 2022; 23:e202200274. [PMID: 35925559 PMCID: PMC9804268 DOI: 10.1002/cphc.202200274] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2022] [Revised: 06/23/2022] [Indexed: 01/05/2023]
Abstract
The reaction of unsaturated substrates with hydrogen gas enriched in the para spin isomer leads to products with a high degree of nuclear singlet spin order. This leads to greatly enhanced NMR signals, with important potential applications such as magnetic resonance imaging (MRI) of metabolic processes. Although parahydrogen-induced polarization has the advantage of being cheap, compact, and mobile, especially when performed in ultralow magnetic fields, efficiency is lost when more than a few protons are involved. This strongly restricts the range of compatible substances. We show that these difficulties may be overcome by a combination of deuteration with the application of a sinusoidally modulated longitudinal field as a well as a transverse rotating magnetic field. We demonstrate a six-fold enhancement in the 13 C hyperpolarization of [1-13 C, 2,3-d2 ]-succinic acid, as compared with standard hyperpolarization methods, applied in the same ultralow field regime.
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Whipham JW, Moustafa GAI, Sabba M, Gong W, Bengs C, Levitt MH. Cross-correlation effects in the solution NMR spectra of near-equivalent spin-1/2 pairs. J Chem Phys 2022; 157:104112. [DOI: 10.1063/5.0107221] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The nuclear magnetic resonance (NMR) spectra of spin-1/2 pairs contain four peaks, with two inner peaks much stronger than the outer peaks in the near-equivalence regime. We have observed that the strong inner peaks have significantly different linewidths when measurements were performed on a 13C2-labelled triyne derivative. This linewidth difference may be attributed to strong cross-correlation effects. We develop the theory of cross-correlated relaxation in the case of near-equivalent homonuclear spin-1/2 pairs, in the case of a molecule exhibiting strongly anisotropic rotational diffusion. Good agreement is found with the experimental NMR lineshapes.
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Ajavakom V, Pandokrak P, Salim SS, Moustafa GAI, Bellingham RK, Hill-Cousins JT, Ajavakom A, Brown R. Formation of seven-membered rings by RCM of vinyl bromides. Synlett 2022. [DOI: 10.1055/a-1845-4195] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Grubbs II catalyst mediated ring-closing metathesis (RCM) of mono-brominated dienes is reported to proceed in moderate to good yields (40–80%) where the linking chain contains five atoms, leading to carbocyclic and heterocyclic 7-membered bromo-olefins. Notably, RCM to form 5-, 6- or 8-membered bromo-olefins was unsuccessful, with the exception of one example where RCM afforded diethyl 3-bromocyclohex-3-ene-1,1-dicarboxylate. In this case a bromomethyl-substituted cyclohexene was obtained as a byproduct. The utility of selected bromo-olefin RCM products was demonstrated through their participation in Suzuki-Miyaura reactions. Vinyl halide exchange (BrCl) was noted as a side reaction under RCM conditions.
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Kasama K, Hinami Y, Mizuno K, Horino S, Nishio T, Yuki C, Kanomata K, Moustafa GAI, Gröger H, Akai S. Lipase-Catalyzed Kinetic Resolution of <i>C</i><sub>1</sub>-Symmetric Heterocyclic Biaryls. Chem Pharm Bull (Tokyo) 2022; 70:391-399. [DOI: 10.1248/cpb.c22-00021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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Roy SS, Iali W, Moustafa GAI, Levitt MH. Tuning of pH enables carbon-13 hyperpolarization of oxalates by SABRE. Chem Commun (Camb) 2022; 58:2291-2294. [PMID: 35080536 DOI: 10.1039/d1cc06973j] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Nuclear spin hyperpolarization transforms typically weak NMR responses into strong signals paving the way for low-gamma nuclei detection within practical time-frames. SABRE (Signal Amplification by Reversible Exchange) is a particularly popular hyperpolarization technique due to its simplicity but the pool of molecules it can polarize is limited. The recent advancement in the form of co-ligands has made SABRE applicable towards molecules with O-donor sites e.g. pyruvate, a key step towards its potential clinical application. Here we explore the SABRE hyperpolarization of another compound with an alpha-keto motif, namely oxalate. We show that hyperpolarization of oxalate may be achieved by adjusting the pH in the presence of sulfoxide co-ligands. The SABRE effect for oxalate in methanol solutions is most effective for the mono-protonated form, which is dominant in the solution around pH ∼2.8. The polarization levels become markedly lower at both higher and lower pH. Employing 50% enriched pH2 we achieve up to 0.33% net 13C polarization in mono-protonated oxalate. In an alternative procedure we show that the hyperpolarization effect in oxalates can also be realised by synthesizing an esterified version of it, without any substantive pH implications. Further, the procedures to create hyperpolarized singlet orders in such substrates are also investigated.
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Miller IR, McLean NJ, Moustafa GAI, Ajavakom V, Kemp SC, Bellingham RK, Camp NP, Brown RCD. Transition-Metal-Mediated Chemo- and Stereoselective Total Synthesis of (-)-Galanthamine. J Org Chem 2022; 87:1325-1334. [PMID: 35007075 DOI: 10.1021/acs.joc.1c02638] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
An asymmetric synthetic route to (-)-galanthamine (1), a pharmacologically active Amaryllidaceae alkaloid used for the symptomatic treatment of early onset Alzheimer's disease, was successfully established with very high levels of stereocontrol. The key to achieving high chemo- and stereo-selectivity in this approach was the use of transition-metal-mediated reactions, namely, enyne ring-closing metathesis, Heck coupling, and titanium-based asymmetric allylation.
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Hussein AA, Ma Y, Moustafa GAI. Predominance of the second cycle in homogeneous Os-catalyzed dihydroxylation: the nature of Os( vi) → Os( viii) reoxidation and unprecedented roles of amine- N-oxides. Catal Sci Technol 2022. [DOI: 10.1039/d1cy02107a] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Our detailed DFT study of Os-catalyzed alkene dihydroxylation revealed that the reaction predominantly proceeds via a second cycle initiated by the formation of a putative Os(viii)trioxoglycolate as a highly reactive intermediate.
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Iali W, Moustafa GAI, Dagys L, Roy SS. 15 N hyperpolarisation of the antiprotozoal drug ornidazole by Signal Amplification By Reversible Exchange in aqueous medium. MAGNETIC RESONANCE IN CHEMISTRY : MRC 2021; 59:1199-1207. [PMID: 33656772 DOI: 10.1002/mrc.5144] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/20/2020] [Revised: 02/19/2021] [Accepted: 02/24/2021] [Indexed: 06/12/2023]
Abstract
Signal amplification by reversible exchange (SABRE) offers a cost-effective route to boost nuclear magnetic resonance (NMR) signal by several orders of magnitude by employing readily available para-hydrogen as a source of hyperpolarisation. Although 1 H spins have been the natural choice of SABRE hyperpolarisation since its inception due to its simplicity and accessibility, limited spin lifetimes of 1 H makes it harder to employ them in a range of time-dependent NMR experiments. Heteronuclear spins, for example, 13 C and 15 N, in general have much longer T1 lifetimes and thereby are found to be more suitable for hyperpolarised biological applications as demonstrated previously by para-hydrogen induced polarisation (PHIP) and dynamic nuclear polarisation (DNP). In this study we demonstrate a simple procedure to enhance 15 N signal of an antibiotic drug ornidazole by up to 71,000-folds with net 15 N polarisation reaching ~23%. Further, the effect of co-ligand strategy is studied in conjunction with the optimum field transfer protocols and consequently achieving 15 N hyperpolarised spin lifetime of >3 min at low field. Finally, we present a convenient route to harness the hyperpolarised solution in aqueous medium free from catalyst contamination leading to a strong 15 N signal detection for an extended duration of time.
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Bengs C, Dagys L, Moustafa GAI, Whipham JW, Sabba M, Kiryutin AS, Ivanov KL, Levitt MH. Nuclear singlet relaxation by chemical exchange. J Chem Phys 2021; 155:124311. [PMID: 34598559 DOI: 10.1063/5.0066182] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
The population imbalance between nuclear singlet states and triplet states of strongly coupled spin-1/2 pairs, also known as nuclear singlet order, is well protected against several common relaxation mechanisms. We study the nuclear singlet relaxation of 13C pairs in aqueous solutions of 1,2-13C2 squarate over a range of pH values. The 13C singlet order is accessed by introducing 18O nuclei in order to break the chemical equivalence. The squarate dianion is in chemical equilibrium with hydrogen-squarate (SqH-) and squaric acid (SqH2) characterized by the dissociation constants pK1 = 1.5 and pK2 = 3.4. Surprisingly, we observe a striking increase in the singlet decay time constants TS when the pH of the solution exceeds ∼10, which is far above the acid-base equilibrium points. We derive general rate expressions for chemical-exchange-induced nuclear singlet relaxation and provide a qualitative explanation of the TS behavior of the squarate dianion. We identify a kinetic contribution to the singlet relaxation rate constant, which explicitly depends on kinetic rate constants. Qualitative agreement is achieved between the theory and the experimental data. This study shows that infrequent chemical events may have a strong effect on the relaxation of nuclear singlet order.
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Aziz HA, Moustafa GAI, Abuo-Rahma GEDA, Rabea SM, Hauk G, Krishna VS, Sriram D, Berger JM, Abbas SH. Synthesis and antimicrobial evaluation of new nitric oxide-donating fluoroquinolone/oxime hybrids. Arch Pharm (Weinheim) 2020; 354:e2000180. [PMID: 32959443 DOI: 10.1002/ardp.202000180] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2020] [Revised: 08/11/2020] [Accepted: 08/31/2020] [Indexed: 01/06/2023]
Abstract
A new series of nitric oxide-donating fluoroquinolone/oximes was prepared in this study. The nitric oxide release from the prepared compounds was measured using a modified Griess colorimetric method. The antitubercular evaluation of the synthesized compounds indicated that ketone derivatives 2b and 2e and oximes 3b and 3d exhibited somewhat higher activity than their respective parent fluoroquinolones. Mycobacterial DNA cleavage studies and molecular modeling of Mycobacterium tuberculosis DNA gyrase were pursued to explain the observed bioactivity. More important, antibacterial evaluation showed that oximes 3c-e are highly potent against Klebsiella pneumoniae, with minimum inhibitory concentration (MIC) values of 0.06, 0.08, and 0.034 µM, respectively, whereas ketone 2c and oxime 4c are more active against Staphylococcus aureus than ciprofloxacin (MIC values: 0.7, 0.38, and 1.6 µM, respectively). Notably, the antipseudomonal activities of compounds 2a and 4c were much higher than those of their respective parent fluoroquinolones.
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Hussein AA, Al-Hadedi AAM, Mahrath AJ, Moustafa GAI, Almalki FA, Alqahtani A, Shityakov S, Algazally ME. Mechanistic investigations on Pinnick oxidation: a density functional theory study. ROYAL SOCIETY OPEN SCIENCE 2020; 7:191568. [PMID: 32257322 PMCID: PMC7062072 DOI: 10.1098/rsos.191568] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/08/2019] [Accepted: 01/13/2020] [Indexed: 05/04/2023]
Abstract
A computational study on Pinnick oxidation of aldehydes into carboxylic acids using density functional theory (DFT) calculations has been evaluated with the (SMD)-M06-2X/aug-pVDZ level of theory, leading to an important understanding of the reaction mechanism that agrees with the experimental observations and explaining the substantial role of acid in driving the reaction. The DFT results elucidated that the first reaction step (FRS) proceeds in a manner where chlorous acid reacts with the aldehyde group through a distorted six-membered ring transition state to give a hydroxyallyl chlorite intermediate that undergoes a pericyclic fragmentation to release the carboxylic acid as a second reaction step (SRS). 1H NMR experiments and simulations showed that hydrogen bonding between carbonyl and t-butanol is unlikely to occur. Additionally, it was found that the FRS is a rate-determining and thermoneutral step, whereas SRS is highly exergonic with a low energetic barrier due to the Cl(III) → Cl(II) reduction. Frontier molecular orbital analysis, intrinsic reaction coordinate, molecular dynamics and distortion/interaction analysis further supported the proposed mechanism.
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Abbass SA, Moustafa GAI, Hassan HA, Abuo-Rahma GEDA. Facile one-pot three-component synthesis of 4,6-diaryl-3,4-dihydropyrimidine-2(1 H)-thiones under ultrasonic irradiation. SYNTHETIC COMMUN 2019. [DOI: 10.1080/00397911.2019.1652759] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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15
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Moustafa GAI, Kasama K, Higashio K, Akai S. Base-promoted lipase-catalyzed kinetic resolution of atropisomeric 1,1′-biaryl-2,2′-diols. RSC Adv 2019; 9:1165-1175. [PMID: 35518007 PMCID: PMC9059663 DOI: 10.1039/c8ra09070j] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2018] [Accepted: 12/24/2018] [Indexed: 12/21/2022] Open
Abstract
Herein we report a dramatic acceleration of the lipase-catalyzed kinetic resolution of atropisomeric 1,1′-biaryl-2,2′-diols by the addition of sodium carbonate. This result likely originates from the increased nucleophilicity of the phenolic hydroxyl group toward the acyl-enzyme intermediate. Under these conditions, various substituted C2-symmetric and non-C2-symmetric binaphthols and biphenols were efficiently resolved with ∼50% conversion in only 13–30 h with excellent enantioselectivity. The addition of a stoichiometric amount of Na2CO3 dramatically accelerates the lipase-catalyzed kinetic resolution of a range of atropisomeric 1,1′-biaryl-2,2′-diols.![]()
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Moustafa GAI, Oki Y, Akai S. Innenrücktitelbild: Lipase-Catalyzed Dynamic Kinetic Resolution of C
1
- and C
2
-Symmetric Racemic Axially Chiral 2,2′-Dihydroxy-1,1′-biaryls (Angew. Chem. 32/2018). Angew Chem Int Ed Engl 2018. [DOI: 10.1002/ange.201806826] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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Moustafa GAI, Oki Y, Akai S. Inside Back Cover: Lipase-Catalyzed Dynamic Kinetic Resolution of C
1
- and C
2
-Symmetric Racemic Axially Chiral 2,2′-Dihydroxy-1,1′-biaryls (Angew. Chem. Int. Ed. 32/2018). Angew Chem Int Ed Engl 2018. [DOI: 10.1002/anie.201806826] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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Moustafa GAI, Oki Y, Akai S. Lipase-Catalyzed Dynamic Kinetic Resolution of C 1 - and C 2 -Symmetric Racemic Axially Chiral 2,2'-Dihydroxy-1,1'-biaryls. Angew Chem Int Ed Engl 2018; 57:10278-10282. [PMID: 29704286 DOI: 10.1002/anie.201804161] [Citation(s) in RCA: 64] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2018] [Indexed: 01/10/2023]
Abstract
We have discovered that the racemization of configurationally stable, axially chiral 2,2'-dihydroxy-1,1'-biaryls proceeds with a catalytic amount of a cyclopentadienylruthenium(II) complex at 35-50 °C. Combining this racemization procedure with lipase-catalyzed kinetic resolution led to the first lipase/metal-integrated dynamic kinetic resolution of racemic axially chiral biaryl compounds. The method was applied to the synthesis of various enantio-enriched C1 - and C2 -symmetric biaryl diols in yields of up to 98 % and enantiomeric excesses of up to 98 %, which paves the way for new developments in the field of asymmetric synthesis.
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Moustafa GAI, Oki Y, Akai S. Lipase-Catalyzed Dynamic Kinetic Resolution of C
1
- and C
2
-Symmetric Racemic Axially Chiral 2,2′-Dihydroxy-1,1′-biaryls. Angew Chem Int Ed Engl 2018. [DOI: 10.1002/ange.201804161] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Moustafa GAI, Saku Y, Aoyama H, Yoshimitsu T. A new route to platencin via decarboxylative radical cyclization. Chem Commun (Camb) 2014; 50:15706-9. [PMID: 25361063 DOI: 10.1039/c4cc07316a] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A new approach to platencin, a potent antibiotic isolated from Streptomyces platensis, has been established. The highly congested tricyclic core of the natural product was successfully constructed by decarboxylative radical cyclization of an alkynyl silyl ester with Pb(OAc)4 in the presence of pyridine in refluxing 1,4-dioxane. The key decarboxylation, which likely takes place via lead(IV) esterification followed by carbon-centered radical generation and subsequent capture of the radical with a triple bond, allows the rapid construction of the twisted polycyclic system.
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Moustafa GAI, Suizu H, Aoyama H, Arai M, Akai S, Yoshimitsu T. Enantiospecific Synthesis and Cytotoxicity Evaluation of Ligudentatol: A Programmed Aromatization Approach to the 2,3,4-Trisubstituted Phenolic Motif via Visible-Light-Mediated Group Transfer Radical Cyclization. Chem Asian J 2014; 9:1506-10. [DOI: 10.1002/asia.201400110] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2014] [Indexed: 11/06/2022]
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Moustafa GAI, Kamada Y, Tanaka T, Yoshimitsu T. Stereoconvergent route to chiral cyclohexenone building blocks: formal synthesis of (-)-dysidiolide. Org Biomol Chem 2013; 10:8609-15. [PMID: 23042006 DOI: 10.1039/c2ob26532j] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A stereoconvergent access to chiral carbocyclic building blocks is reported. 6-(3'-Hydroxy-4'-methylpent-4'-enyl)-3-methoxy cyclohex-2-enone () that consists of four stereoisomers, i.e., racemic ca. 1 : 1 diastereomers, is converted to enantiomerically pure carbocycles through a combination of regioselective catalytic asymmetric reduction and alkylative remote stereoinduction. The present stereoconvergent strategy has allowed the formal synthesis of bioactive (-)-dysidiolide.
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Moustafa GAI, Nojima S, Yamano Y, Aono A, Arai M, Mitarai S, Tanaka T, Yoshimitsu T. Potent growth inhibitory activity of (±)-platencin towards multi-drug-resistant and extensively drug-resistant Mycobacterium tuberculosis. MEDCHEMCOMM 2013. [DOI: 10.1039/c3md00016h] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Moustafa GAI, Kamada Y, Tanaka T, Yoshimitsu T. Stereoselective α-Quaternization of 3-Methoxycycloalk-2-enones via 1,4-Diastereoinduction of Alkoxy Dienolates. J Org Chem 2012; 77:1202-7. [DOI: 10.1021/jo2022789] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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