- Bio-derived nanosilica-anchored Cu(II)-organoselenium complex as an efficient retrievable catalyst for alcohol oxidation
-
A new copper(II) complex supported onto rice-husk-derived nanosilica was prepared from 2,6-bis((phenylselanyl)methyl)pyridine, salicylaldehyde and copper acetate monohydrate, Cu(OAc)2·H2O. The as-synthesized complex Cu(II)SeNSe@imine-nanoSiO2 (Complex I) was extensively characterized with FT-IR, powder XRD, SEM-EDX, solid-state UV-Vis, ESR, XPS, TGA and BET surface area analysis. The catalytic activity of the complex was explored for alcohol oxidation reactions using H2O2 as oxidant and acetonitrile as solvent. For comparison, we have also prepared an analogous homogeneous catalyst (Complex II) and characterized it with FT-IR, UV-Vis, LC-MS and ESR analyses. Its catalytic activity was also screened to the same reaction. The immobilized catalyst showed better efficiency with 75%–95% isolated yield compared with the homogeneous one for alcohol oxidation with at least five times recyclability without profound loss in activity.
- Gogoi, Rajjyoti,Borah, Geetika
-
-
- 3-(5-METHOXY-1-OXOISOINDOLIN-2-YL)PIPERIDINE-2,6-DIONE DERIVATIVES AND USES THEREOF
-
The present disclosure relates to compounds of formula (I') and pharmaceutical compositions and their use in reducing Widely Interspaced Zinc Finger Motifs (WIZ) expression levels, or inducing fetal hemoglobin (HbF) expression, and in the treatment of inherited blood disorders (e.g., hemoglobinopathies, e.g., beta-hemoglobinopathies), such as sickle cell disease and beta-thalassemia.
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-
Page/Page column 317-318
(2021/06/26)
-
- Exploring the dNTP -binding site of HIV-1 reverse transcriptase for inhibitor design
-
HIV-1 reverse transcriptase (RT) plays a central role in the viral life cycle, and roughly half of the FDA-approved anti-HIV drugs are targeting RT. Nucleoside analogs (NRTIs) require cellular phosphorylation for binding to RT, and to bypass this rate-limiting path, we designed a new series of acyclic nucleoside phosphonate analogs as nucleoside triphosphate mimics, aiming at the chelation of the catalytic Mg2+ ions via a phosphonate and/or a carboxylic acid group. Novel synthetic procedures were developed to access these nucleoside phosphonate analogs. X-ray structures in complex with HIV-1 RT/dsDNA demonstrated that their binding modes are distinct from that of our previously reported compound series. The impact of chain length, chirality and linker atom have been discussed. The detailed structural understanding of these new compounds provides opportunities for designing new class of HIV-1 RT inhibitors.
- Das, Kalyan,De Jonghe, Steven,Gu, Weijie,Herdewijn, Piet,Martinez, Sergio,Nguyen, Hoai,Rozenski, Jef,Schols, Dominique,Singh, Abhimanyu K.
-
-
- General Asymmetric Synthetic Strategy for the α-Alkylated 2,5,6-Trisubstituted Pyran of Indanomycin and Related Natural Products
-
A general synthetic strategy for convergent asymmetric synthesis of C1–C10 fragment of tetraene-containing natural product indanomycin was achieved starting from 2-(benzyloxy)acetaldehyde which in turn was obtained from very inexpensive material cis-1,4-butene-diol. Key steps include Evans' aldol reaction, HWE olefination, iodine-catalyzed tandem isomerization followed by C–O and C–C bond formation similar to our earlier report in constructing the trans-2,6-disubstituted dihydropyran ring and Evans' asymmetric alkylation.
- Mohapatra, Debendra K.,Padma, Ravishetty,Srinivas, Beduru,Yadav, Jhillu S.
-
-
- SPIRO-LACTAM NMDA RECEPTOR MODULATORS AND USES THEREOF
-
Disclosed are compounds having potency in the modulation of NMDA receptor activity. Such compounds can be used in the treatment of conditions such as depression and related disorders as well as other disorders.
- -
-
-
- Correction to: Nickel-catalyzed asymmetric reductive cross-coupling to access 1,1-diarylalkanes (Journal of the American Chemical Society (2017) 139 (5684-5687) DOI: 10.1021/jacs.7b01705)
-
Pages 5684 and 5685, Table of Contents, and Supporting Information. The stereochemistry of L1, depicted as the (S,S)- enantiomer in Figure 1, Table 1, the TOC graphic (identical to Figure 1), and the Supporting Information of the original publication, was incorrect. (R,R)-L1 was used in this study. The stereochemistry of (R,R)-L1 has been confirmed by singlecrystal X-ray diffraction; the X-ray diffraction data and CIF file for (R,R)-L1 have been added to the Supporting Information. The corrected TOC graphic/Figure 1 is shown here. (R,R)-L4 and (R,R)-L5 were also used in Table 1 and incorrectly depicted as (S,S)-L4 and (S,S)-L5 in the original publication. To reflect that different enantiomeric series of catalysts were used, Table 1 has been updated to indicate that entries 2, 3, and 6 produce (S)-3a. This correction does not change the stereochemical assignment of the diarylalkane products, or the conclusions of the Communication. The stereochemistry of the products was assigned by obtaining an X-ray structure of diarylalkane 3k, and the rest of the compounds were assigned by analogy. (Table Presented).
- Poremba, Kelsey E.,Kadunce, Nathaniel T.,Suzuki, Naoyuki,Cherney, Alan H.,Reisman, Sarah E.
-
supporting information
p. 7746 - 7746
(2018/06/26)
-
- Novel compound 6,6-dimethyl tetrahydropyran-2-methanol and preparing method thereof
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The invention discloses a novel compound that is 6,6-dimethyl tetrahydropyran-2-methanol and a preparing method thereof. The method includes preparing benzyloxy ethanol by utilizing a sodium alkoxideprocess; then oxidizing the benzyloxy ethanol into benzyloxy acetaldehyde by utilizing a swern oxidation process; reacting the benzyloxy acetaldehyde and allyltributyltin prepared by utilizing a Grignard reaction to obtain 1-(benzyloxy)-4-penten-2-ol; subjecting the 1-(benzyloxy)-4-penten-2-ol and acetone to cyclization under catalysis of trimethylchlorosilane and potassium iodide to obtain 4-iodo-6,6-dimethyl tetrahydropyran-2-methanol; and subjecting the 4-iodo-6,6-dimethyl tetrahydropyran-2-methanol to hydrogenation to remove iodine to obtain the target product that is the 6,6-dimethyl tetrahydropyran-2-methanol. According to the method, reactions are relatively mild, products can be easily treated and purified, and the method is suitable for batch preparation, and therefore the methodhas important application value.
- -
-
Paragraph 0014; 0017-0018; 0025; 0031
(2018/04/03)
-
- Electrophile-Dependent Alkylations of Lithiated 4-Alkoxyalk-4-enenitriles
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Alkylations of acyclic, lithiated 4-alkoxyalk-4-enenitriles are highly diastereoselective with an unusual electrophile-dependent preference. Alkyl halides, sulfur, chlorine, and acyl cyanide electrophiles intercept a series of lithiated 4-alkoxyalk-4-enenitriles to install contiguous tertiary-quaternary stereocenters with high diastereoselectivity, whereas acylations with ester and carbonate electrophiles are modestly selective. The diastereoselectivity is consistent with electrophilic attack on the most accessible face of the lithated nitrile for most electrophiles except ester and carbonate electrophiles, which likely precoordinate the lithiated nitrile before acylation. Intercepting the lithiated 4-alkoxyalk-4-enenitriles with a range of electrophiles provide insight into the criteria for otherwise challenging diastereoselective alkylations and acylations of acyclic nitriles.
- Pitta, Bhaskar R.,Steward, Omar W.,Fleming, Fraser F.
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p. 2753 - 2762
(2018/03/13)
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- Preparation method of rosuvastatin calcium medicine intermediate
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The invention belongs to the technical field of medicine chemicals, and particularly relates to a preparation method of a rosuvastatin calcium medicine intermediate. The preparation method comprises the following steps of using monochloroacetaldehyde as the raw material; substituting, condensing, and chirally catalyzing, so as to prepare a compound V; protecting by 2,2-dimethoxypropane, and debenzylating, so as to obtain a target compound I. The preparation method has the advantages that the raw materials are easy to obtain; (S)-5-benzyl-2,2,3-trimethyl-4-thioketone is used as a catalyst for stereo selective reduction, the reaction conditions are mild, the yield rate is higher, and the industrialization production of the component I is easy.
- -
-
Paragraph 0030; 0046; 0052
(2018/11/03)
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- Nickel-Catalyzed Asymmetric Reductive Cross-Coupling to Access 1,1-Diarylalkanes
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An asymmetric Ni-catalyzed reductive cross-coupling of (hetero)aryl iodides and benzylic chlorides has been developed to prepare enantioenriched 1,1-diarylalkanes. As part of these studies, a new chiral bioxazoline ligand, 4-heptyl-BiOX (L1), was developed in order to obtain products in synthetically useful yield and enantioselectivity. The reaction tolerates a variety of heterocyclic coupling partners, including pyridines, pyrimidines, indoles, and piperidines.
- Poremba, Kelsey E.,Kadunce, Nathaniel T.,Suzuki, Naoyuki,Cherney, Alan H.,Reisman, Sarah E.
-
supporting information
p. 5684 - 5687
(2017/05/04)
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- Solid supported Hayashi–J?rgensen catalyst as an efficient and recyclable organocatalyst for asymmetric Michael addition reactions
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A comparison of three different catalytic systems for the efficient, asymmetric synthesis of N-({(3R,4R)-4-[(benzyloxy)methyl]pyrrolidin-3-yl}methyl)-N-(2-methylpropyl)benzenesulfonamide 1 (BZN) is described. The presented strategy is based on the organocatalytic Michael addition of aldehyde 2 to trans-nitroalkene 3, and subsequent reductive cyclization. High yields, enantio-, and diastereoselectivities were achieved in the Michael addition by application of a POSS- or Wang resin-supported Hayashi–J?rgensen catalyst.
- Szcze?niak, Piotr,Staszewska-Krajewska, Olga,Furman, Bart?omiej,Mlynarski, Jacek
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supporting information
p. 1765 - 1773
(2017/12/04)
-
- Total Synthesis of Ovafolinins A and B: Unique Polycyclic Benzoxepin Lignans through a Cascade Cyclization
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Ovafolinins A and B, isolated from Lyonia ovalifolia var. elliptica, are lignans that contain a unique bridged structure containing a penta- and tetracyclic benzoxepin and an aryl tetralin. We report the first total synthesis of these natural products in which an acyl-Claisen rearrangement was initially utilized to construct the lignan backbone with correct relative stereochemistry. Judicious use of a bulky protecting group placed reactive moieties in the correct orientation, thereby resulting in a cascade reaction to form the bridged benzoxepin/aryl tetralin from a linear precursor in a single step. Modification of this route allowed the enantioselective synthesis of (+)-ovafolinins A and B, which confirmed the absolute stereochemistry, and comparison of optical rotation suggests that these compounds are found as scalemic mixtures in nature.
- Davidson, Samuel J.,Barker, David
-
p. 9483 - 9486
(2017/08/01)
-
- Total synthesis of (-)-bicubebin A, B, (+)-bicubebin C and structural reassignment of (-)-cis-cubebin
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The first total synthesis of (-)-bicubebin A, and two previously unreported dilignans, (-)-bicubebin B and (+)-bicubebin C has been achieved through the dimerization of (-)-cubebin, confirming the structure and absolute stereochemistry of (-)-bicubebin A. Analysis of the data for (-)-bicubebin B showed it matched that of reported compound (-)-cis-cubebin. The NMR data of the subsequently synthesized proposed structure of cis-cubebin confirmed that its original proposed structure was incorrect.
- Davidson, Samuel J.,Pearce, A. Norrie,Copp, Brent R.,Barker, David
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p. 5368 - 5371
(2017/11/06)
-
- POLYMYXIN ANALOGS USEFUL AS ANTIBIOTIC POTENTIATORS
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The disclosure provides compounds of the formula (I) or a tautomer thereof, or a pharmaceutically acceptable salt of either of the foregoing. The variables A, R1, and R2 are defined in the disclosure. The disclosure further includes pharmaceutical compositions comprising a compound of formula I together with at least one pharmaceutically acceptable carrier. The disclosure also includes a method of sensitizing bacteria to an antibacterial agent, comprising administering to a patient infected with the bacteria, simultaneously or sequentially, a therapeutically effective amount of the antibacterial agent and a compound of formula (I).
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-
- A Divergent Approach for the Synthesis of d - And l -4′-Ethynyl Dioxolane Nucleosides with Potent Anti-HIV Activity
-
Novel 4′-C-ethynyl isomeric dioxolane nucleoside analogues (β-d, α-d, β-l, and α-l, respectively) are successfully synthesized via a divergent strategy from the common starting material, (Z)-but-2-ene-1,4-diol, and are characterized and evaluated for their anti-HIV-1 and anti-HIV-2 activities. The β-d and β-l products display potent in vitro activities against HIV-1 (IIIB) with EC50 values of 0.75 and 0.87 μM, respectively, and against HIV-2 (ROD) with EC50 values of 0.75 and 0.35 μM, respectively, being better in comparison with 3TC [EC50, 5.27 μM (HIV-1) and 1.30 μM (HIV-2)]. The β-d and β-l nucleosides also potently inhibit different drug-resistant strains of the HIV-1 virus (L100I, K103N, Y181C, and V106A). The selectivity indices and cytotoxic profiles of the β-d and β-l nucleosides are much better than those of the standard drugs AZT and d4T.
- Singh, Sarbjit,Gajulapati, Veeraswamy,Kim, Minkyoung,Goo, Ja-Il,Lee, Jae Kyun,Lee, Kyeong,Lee, Chong-Kyo,Jeong, Lak Shin,Choi, Yongseok
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p. 3050 - 3056
(2016/09/09)
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- Percarboxylic Acid Oxidation of α-Hydroxy-Substituted Alkoxyallenes: The Unexpected Formation of Acyloxy-Substituted 1,2-Diketones and the Synthesis of Functionalized Quinoxalines
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Treatment of α-hydroxy-substituted methoxyallene derivatives with meta-chloroperbenzoic acid provided acyloxy-substituted 1,2-diketones in moderate yields. A mechanism for the formation of these unexpected products is proposed. The configuration of the enantiopure compound (S)-1-(3-methylquinoxalin-2-yl)-1-(4-nitrobenzoyl?oxy)propan-2-yl 3-chlorobenzoate - determined by X-ray crystal structure analysis - indicates the intermediacy of a carbenium ion during formation of the 1,2-diketones. The functionalized 1,2-diketones are valuable starting materials for a variety of products as demonstrated by the synthesis of quinoxalines, an imidazole derivative, and electron-deficient alkenes.
- Klemme, Robby,Bentz, Christoph,Zukowski, Tomasz,Schefzig, Luise,Lentz, Dieter,Reissig, Hans-Ulrich,Zimmer, Reinhold
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supporting information
p. 1491 - 1501
(2016/05/24)
-
- Selective Enzymatic Transformation to Aldehydes in vivo by Fungal Carboxylate Reductase from Neurospora crassa
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The enzymatic reduction of carboxylic acids is in its infancy with only a handful of biocatalysts available to this end. We have increased the spectrum of carboxylate-reducing enzymes (CARs) with the sequence of a fungal CAR from Neurospora crassa OR74A (NcCAR). NcCAR was efficiently expressed in E. coli using an autoinduction protocol at low temperature. It was purified and characterized in vitro, revealing a broad substrate acceptance, a pH optimum at pH 5.5–6.0, a Tmof 45 °C and inhibition by the co-product pyrophosphate which can be alleviated by the addition of pyrophosphatase. The synthetic utility of NcCAR was demonstrated in a whole-cell biotransformation using the Escherichia coli K-12 MG1655 RARE strain in order to suppress overreduction to undesired alcohol. The fragrance compound piperonal was prepared from piperonylic acid (30 mM) on gram scale in 92 % isolated yield in >98% purity. This corresponds to a productivity of 1.5 g/L/h. (Figure presented.).
- Schwendenwein, Daniel,Fiume, Giuseppe,Weber, Hansj?rg,Rudroff, Florian,Winkler, Margit
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p. 3414 - 3421
(2016/11/13)
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- Reactions of peroxide products of ozonolysis of allyl ethers/esters in the AcOH-CH2Cl2 system on treatment with semicarbazide hydrochloride
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Background: A one-pot method for the preparation of the corresponding alkoxy acetic acids by low-temperature ozonolysis of allyl ethers/esters followed by treatment with semicarbazide hydrochloride has been suggested. The reaction occurs via formation of acetoxyhydroperoxide, subsequent reduction of which depends on the process temperature and the nature of the starting substrate. Objective: The article is aimed at the development of one-pot method for obtaining practically important alkoxy acetic acids, because the ozonolytic cleavage of a ?=? double bond is the key step in full syntheses of many biologically active compounds. Methods: We used a low temperature ozonolysis of functionally substituted olefins in the system acetic acid-methylene dichloride followed by reduction of semicarbazide hydrochloride. To create a method we have used available allyl ethers/esters as starting materials. Results: We investigated reaction of the peroxide products of ozonolysis of monoallyl ethers, ester and diallyl ethers in an AcOH/CH2Cl2 mixture on treatment with semicarbazide hydrochloride at various temperatures. We have discovered that the selectivity of reduction of acetoxyhydroperoxide formed at the first stage depends both on the process temperature and on the nature of the starting substrate. A decrease in temperature favors acid hydrolysis and formation of a carboxylic acid. Conclusion: We have proposed a simple and highly efficient one-pot method for the preparation alkoxy acetic acids without isolation of intermediate peroxides.
- Raskil'dina, Gulnara Z.,Legostaeva, Yuliya V.,Garifullina, Liliya R.,Sultanova, Rimma M.,Ishmuratov, Gumer Y.,Zlotskii, Simon S.
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p. 652 - 656
(2017/01/13)
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- Development of a sensitive bioluminogenic probe for imaging highly reactive oxygen species in living rats
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A sensitive bioluminogenic probe for highly reactive oxygen species (hROS), SO3H-APL, was developed based on the concept of dual control of bioluminescence emission by means of bioluminescent enzyme-induced electron transfer (BioLeT) and modulation of cell-membrane permeability. This probe enables non-invasive visualization of physiologically relevant amounts of hROS generated deep inside the body of living rats for the first time. It is expected to serve as a practical analytical tool for investigating a wide range of biological functions of hROS in vivo. The design concept should be applicable to other in vivo bioluminogenic probes. You light up my life: A sensitive bioluminogenic probe for highly reactive oxygen species (hROS) was developed based on the concept of dual control of bioluminescence emission by means of bioluminescent enzyme-induced electron transfer (BioLeT) and modulation of cell-membrane permeability. This probe enables non-invasive visualization of physiologically relevant amounts of hROS generated deep inside the body of living rats.
- Kojima, Ryosuke,Takakura, Hideo,Kamiya, Mako,Kobayashi, Eiji,Komatsu, Toru,Ueno, Tasuku,Terai, Takuya,Hanaoka, Kenjiro,Nagano, Tetsuo,Urano, Yasuteru
-
supporting information
p. 14768 - 14771
(2016/02/05)
-
- (Z)-Selective enol triflation of α-alkoxyacetoaldehydes: Application to synthesis of (Z)-allylic alcohols via cross-coupling reaction and [1,2]-wittig rearrangement
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The stereoselective transformation of α-alkoxyacetoaldehydes to the corresponding (Z)-vinyl triflates was achieved by treatment with phenyl triflimide and DBU. The stereochemistry was explained by the "syn-effect," which was attributed primarily to an σ → π interaction. The β-alkoxy vinyl triflates obtained were applied to the stereoselective synthesis of structurally diverse (Z)-allylic alcohols via transition metal-catalyzed cross-coupling reaction and [1,2]-Wittig rearrangement.
- Kurosawa, Fumiya,Nakano, Takeo,Soeta, Takahiro,Endo, Kohei,Ukaji, Yutaka
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p. 5696 - 5703
(2015/06/16)
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- An efficient and reusable vanadium based catalytic system for room temperature oxidation of alcohols to aldehydes and ketones
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A simple and efficient vanadium based catalyst system for the oxidation of primary and secondary alcohols to aldehydes or ketones is reported using tert-butyl hydroperoxide as oxidizing agent and vanadyl sulfate as catalyst at room temperature. The versatility of the catalytic protocol is studied with wide variety of substrates.
- Sarmah, Gayatri,Bharadwaj, Saitanya K.,Dewan, Anindita,Gogoi, Ankur,Bora, Utpal
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p. 5029 - 5032
(2015/01/08)
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- Evolution of an oxidative dearomatization enabled total synthesis of vinigrol
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The evolution of the synthetic strategy resulting in a total synthesis of vinigrol is presented. Oxidative dearomatization/intramolecular Diels-Alder cycloaddition has served as the successful cornerstone for all of the approaches. Extensive radical cyclization efforts to form the tetracyclic core resulted in interesting and surprising reaction outcomes, none of which could be advanced to vinigrol. These cyclization obstacles were successfully overcome by using Heck instead of radical cyclizations. The total synthesis features a trifluoroethyl ether protecting group being used for the first time in organic synthesis. The logic of its selection and the group's importance beyond protecting the C8a hydroxyl group is presented along with a discussion of strategies for its removal. Because of the compact tetracyclic cage the route is built around many unusual reaction observations and solutions have emerged. For example, a first of its kind Grob fragmentation reaction featuring a trifluoroethyl leaving group has been uncovered, interesting interrupted selenium dioxide allylic oxidations have been observed as well as intriguing catalyst and counterion dependent directed hydrogenations.
- Yang, Qingliang,Draghici, Cristian,Njardarson, Jon T.,Li, Fang,Smith, Brandon R.,Das, Pradipta
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p. 330 - 344
(2014/01/06)
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- A concise and diastereoselective synthesis of piperidine and indolizidine alkaloids via aza-Prins cyclization
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The synthesis of 2-substituted and 2,4-disubstituted piperidine alkaloids such as (±)-coniine, (±)-hydroxypipecolic acid, (±)-pipecolic acid, (±)-coniceine, and (±)-4-hydroxy-2- hydroxy-methyl piperidine have been accomplished in a highly diastereo-selective manner by employing aza-Prins cyclization as a key step to construct the piperidine core of these alkaloids. Georg Thieme Verlag Stuttgart · New York.
- Reddy, Basi V. Subba,Chaya, Dudhmal N.,Yadav, Jhillu S.,Gree, Rene
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experimental part
p. 297 - 303
(2012/03/26)
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- Palladium-catalyzed asymmetric quaternary stereocenter formation
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An efficient palladium catalyst is presented for the formation of benzylic quaternary stereocenters by conjugate addition of arylboronic acids to a variety of β,β-disubstituted carbocyclic, heterocyclic, and acyclic enones. The catalyst is readily prepared from PdCl2, PhBOX, and AgSbF 6, and provides products in up to 99 % enantiomeric excess, with good yields. Based on this strategy, (-)-α-cuparenone has been prepared in only two steps. Copyright
- Gottumukkala, Aditya L.,Matcha, Kiran,Lutz, Martin,De Vries, Johannes G.,Minnaard, Adriaan J.
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supporting information; experimental part
p. 6907 - 6914
(2012/07/01)
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- Asymmetric synthesis of 2-alkyl-substituted tetrahydroquinolines by an enantioselective aza-Michael reaction
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An optically active tetrahydroquinoline intermediate (5) was prepared in 8 steps from monoprotected ethylene glycol, using a Pd-catalysed aza-Michael reaction to induce chirality. This can be transformed into three Galipea alkaloids (angustureine, galipeine and cuspareine). The proximity of a benzyloxy group is found to exert profound effects in several steps of the synthesis.
- Taylor, Laura L.,Goldberg, Frederick W.,Hii, King Kuok Mimi
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experimental part
p. 4424 - 4432
(2012/07/03)
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- Efficient and convenient method for workup of ozonolysis reaction using sodium hydrosulfite
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An efficient and convenient method is reported for reductive workup of the ozon-olysis reaction using sodium hydrosulfite. Comparisons were made between triethylamine and methyl sulfide for their use as a quenching reagent in the ozonolysis of a variety of alkenes. Taylor & Francis Group, LLC.
- Tyagi, Vipin,Gupta, Ashok Kumar
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experimental part
p. 843 - 848
(2012/02/01)
-
- Synthesis of thietane nucleoside with an anomeric hydroxymethyl group
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Thietane nucleoside 5 with an anomeric hydroxymethyl group was synthesized via the Pummerer reaction. The stereochemistry of the sulfoxide and the nature of the protecting group had no significant effect on the yield of the reaction. When a hypervalent iodine reagent was used, sulfide 16 with O-benzoyl protecting groups gave the ring-expanded nucleoside 21. Unfortunately, synthesized compound 6 did not exhibit anti-HSV activity. Copyright
- Nishizono, Naozumi,Akama, Yuji,Agata, Masayuki,Sugo, Michiyasu,Yamaguchi, Yuki,Oda, Kazuaki
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p. 358 - 363
(2011/03/19)
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- Synthesis of three selectively deuterated propylene oxides
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Three different selectively deuterated propylene oxides have been synthesized for use in quasi-elastic neutron scattering studies of the dynamics of propylene oxide within clathrate hydrate cages. Copyright 2011 John Wiley & Sons, Ltd. Three different selectively deuterated propylene oxides have been synthesized for use in quasi-elastic neutron scattering studies of the dynamics of propylene oxide within clathrate hydrate cages. Copyright
- Otley, Kate D.,Saccomano, Benjamin W.,McKee, Silas A.,Nizialek, Gregory A.,Hamilton, David S.,Sherrow, Leighanne K.,Jones, Camille Y.,Rosenstein, Ian J.
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p. 308 - 311
(2012/02/03)
-
- A catalytic tethering strategy: Simple aldehydes catalyze intermolecular alkene hydroaminations
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Herein we describe a catalytic tethering strategy in which simple aldehyde precatalysts enable, through temporary intramolecularity, room-temperature intermolecular hydroamination reactivity and the synthesis of vicinal diamines. The catalyst allows the formation of a mixed aminal from an allylic amine and a hydroxylamine, resulting in a facile intramolecular hydroamination event. The promising enantioselectivities obtained with a chiral aldehyde also highlight the potential of this catalytic tethering approach in asymmetric catalysis and demonstrate that efficient enantioinduction relying only on temporary intramolecularity is possible.
- MacDonald, Melissa J.,Schipper, Derek J.,Ng, Peter J.,Moran, Joseph,Beauchemin, Andre M.
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supporting information; experimental part
p. 20100 - 20103
(2012/02/01)
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- Synthesis and use of a stable aminal derived from TsDPEN in asymmetric organocatalysis
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A stable aminal formed stereoselectively from (R,R)-N-tosyl-1,2-diphenyl-1, 2-ethylenediamine (TsDPEN) is capable of asymmetric organocatalysis of Diels-Alder and α-amination reactions of aldehydes.
- Gosiewska, Silvia,Soni, Rina,Clarkson, Guy J.,Wills, Martin
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supporting information; experimental part
p. 4214 - 4217
(2010/09/12)
-
- Asymmetric total synthesis of glycinoeclepin A: Generation of a novel bridgehead anion species
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The asymmetric total synthesis of glycinoeclepin A, a hatchstimulating agent of the soybean, cyst nematode, was accomplished on the basis of a cyclopentene annulation for constructing the CD ring moiety having contiguous quaternary carbon atoms. Introduction of the A ring moiety was achieved by an alkylation reaction using a 7-oxabicyclo[2.2.1]hex-l-yl anion species.
- Shiina, Yasuhiro,Tomata, Yoshihide,Miyashita, Masaaki,Tanino, Keiji
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scheme or table
p. 835 - 837
(2011/01/10)
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- Asymmetric synthesis of proline-based conformationally constrained tryptophan mimetic
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The synthesis of an optically pure proline-based tryptophan mimetic is described. The strategy involves the in situ generation of an unprecedented allylmetal species containing the indole moiety, and its coupling with a chiral imine. The construction of the 3-substitued proline skeleton is then achieved through a hydrozirconation/iodination sequence applied to the resulting homoallylic amine.
- Delaye, Pierre-Olivier,Vasse, Jean-Luc,Szymoniak, Jan
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supporting information; experimental part
p. 3635 - 3637
(2010/09/06)
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- An expedient procedure for the oxidative cleavage of olefinic bonds with PhI(OAc)2, NMO, and Catalytic OsO4
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(Figure Presented) PhI(OAc)2 In the presence of OsO4 (cat.) and 2,6-lutidine cleaves oleflnlc bonds to yield the corresponding carbonyl compounds, albeit, In some cases, with a-hydroxy ketones as byproduct. A more practical and clean protocol to effect oxidative cleavage of olefinic bonds involves NMO, OsO4 (cat.), 2,6-lutidine, and PhI(OAc) 2.
- Nicolaou,Adsool, Vikrant A.,Hale, Christopher R. H.
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supporting information; experimental part
p. 1552 - 1555
(2010/06/16)
-
- Synthesis of N-heterocycles, beta-amino acids, and allyl amines via aza-payne mediated reaction of ylides and hydroxy aziridines
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An ylide-based aza-Payne rearrangement of 2,3-aziridin-1-ols leads to an efficient process for the preparation of pyrrolidines. The aza-Payne rearrangement under the basic reaction conditions favors the formation of epoxy amines. Subsequent nucleophilic attack of the epoxide by the ylide yields a bis-anion, which upon a 5-exo-tet ring closure yields the desired pyrrolidine, thus completing the relay of the 3-membered the 5-membered nitrogen containing ring system. This process takes place with complete transfer of stereochemical fidelity, and can be applied to sterically hindered aziridinols.
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Page/Page column 24
(2009/01/23)
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- Total synthesis of (+)-azaspiracid-1. An exhibition of the intricacies of complex molecule synthesis
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The synthesis of the marine neurotoxin azaspiracid-1 has been accomplished. The individual fragments were synthesized by catalytic enantioselective processes: A hetero-Diels-Alder reaction to afford the E- and HI-ring fragments, a carbonyl-ene reaction to furnish the CD-ring fragment, and a Mukaiyama aldol reaction to deliver the FG-ring fragment. The subsequent fragment couplings were accomplished by aldol and sulfone anion methodologies. All ketalization events to form the nonacyclic target were accomplished under equilibrating conditions utilizing the imbedded configurations of the molecule to adopt one favored conformation. A final fragment coupling of the anomeric EFGHI-sulfone anion to the ABCD-aldehyde completed the convergent synthesis of (+)-azaspiracid-1.
- Evans, David A.,Kvaerno, Lisbet,Dunn, Travis B.,Beauchemin, Andre,Raymer, Brian,Mulder, Jason A.,Olhava, Edward J.,Juhl, Martin,Kagechika, Katsuji,Favor, David A.
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supporting information; experimental part
p. 16295 - 16309
(2009/05/08)
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- Synthesis, structures, and properties of nine-, twelve-, and eighteen-membered N-benzyloxyethyl cyclic α-peptoids
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N-Benzyloxyethyl cyclic α-peptoids of various size were prepared and their conformational features were investigated by means of computational, spectroscopic, and X-ray crystallographic studies. The Royal Society of Chemistry.
- Maulucci,Izzo,Bifulco,Aliberti,De Cola,Comegna,Gaeta,Napolitano,Pizza,Tedesco,Flot,De Riccardis
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supporting information; experimental part
p. 3927 - 3929
(2009/02/07)
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- Diastereomerically and enantiomerically pure 2,3-disubstituted pyrrolidines from 2,3-aziridin-1-ols using a sulfoxonium ylide: A one-carbon homologative relay ring expansion
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An ylide-based aza-Payne rearrangement of 2,3-aziridin-1-ols leads to an efficient process for the preparation of pyrrolidines. The aza-Payne rearrangement under basic reaction conditions favors the formation of epoxy amines. Subsequent nucleophilic attack of the epoxide by the ylide yields a bis-anion, which upon a 5-exo-tet ring-closure yields the desired pyrrolidine, thus completing the relay of the three-membered to the five-membered nitrogen-containing ring system. This process takes place with complete transfer of stereochemical fidelity and can be applied to sterically hindered aziridinols.
- Schomaker, Jennifer M.,Bhattacharjee, Somnath,Yan, Jun,Borhan, Babak
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p. 1996 - 2003
(2007/10/03)
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- Tetrasubstituted pyrrolidines via a tandem aza-Payne/hydroamination reaction
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A facile tandem aza-Payne/hydroamination reaction of aziridinol is reported, which yields highly functionalized pyrrolidines. Addition of alkynyl Grignards to 2,3-aziridinals yields, in most cases, high syn to anti ratios of the aziridinol. Treatment of the syn-aziridinol with base leads initially to an aza-Payne rearrangement, which juxtaposes the amine and the alkyne in favorable orientation to complete the hydroamination. The anti-aziridinol undergoes the aza-Payne rearrangement, but cannot proceed further with the hydroamination. Copyright
- Schomaker, Jennifer M.,Geiser, Andrea R.,Huang, Rui,Borhan, Babak
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p. 3794 - 3795
(2008/02/01)
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- An efficient and green oxidation of vicinal diols to aldehydes using polymer-supported (diacetoxyiodo)benzene as the oxidant
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An operationally simple and clean oxidation of a variety of vicinal diols to aldehydes using polymer-supported (diacetoxyiodo)benzene (PSDIB) has been developed in high to excellent yields. Protecting groups such as OAc, OR, OBn, OBz and isopropylidene in the substrates were found to be stable under these reaction conditions. The regenerated PSDIB could be reused for the same reaction, affording oxidation products in high yield and purity. Georg Thieme Verlag Stuttgart.
- Chen, Fen-Er,Xie, Bin,Zhang, Ping,Zhao, Jian-Feng,Wang, Hui,Zhao, Lei
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p. 619 - 622
(2007/10/03)
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- Tishchenko reactions of aldehydes promoted by diisobutylaluminum hydride and its application to the macrocyclic lactone formation
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Aliphatic aldehydes react with catalytic amount of Dibal-H in n-pentane to give the corresponding Tishchenko products in good to excellent yields. On contrary, α-silyloxy aldehydes give α-silyloxy ketones via Oppenauer oxidation under similar condition. Tishchenko reaction of ω-alkene aldehydes followed by RCM and hydrogenation affords a convenient method to prepare the 11-37 membered macrocyclic lactones.
- Hon, Yung-Son,Wong, Ying-Chieh,Chang, Chun-Ping,Hsieh, Cheng-Han
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p. 11325 - 11340
(2008/03/12)
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- Asymmetric synthesis of 4-amino-γ-butyrolactones via lithium amide conjugate addition
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Upon treatment with homochiral lithium (R)-N-benzyl-N-(α-methylbenzyl)amide, γ-benzyloxy but-2-enoates undergo competitive conjugate addition and γ-deprotonation, while γ-tert-butyldimethylsilyloxy but-2-enoates undergo exclusive conjugate addition. Treatment of γ-benzyloxy or γ-tert-butyldimethylsilyloxy but-2-enamides with lithium (R)-N-benzyl-N-(α-methylbenzyl)amide furnishes exclusively the γ-benzyloxy- or γ-tert-butyldimethylsilyloxy-β-amino amide products of conjugate addition in high de. The γ-tert-butyldimethylsilyloxy-β-amino butanoate products of conjugate addition readily undergo O-desilylation and concomitant cyclisation to furnish 4-[N-benzyl-N-(α-methylbenzyl)amino]-γ-butyrolactone, which may be stereoselectively functionalised via deprotonation and alkylation?to give the corresponding trans-3-alkyl-4-amino-γ-butyrolactones. Alternatively, stereoselective alkylation of γ-benzyloxy- or γ-tert-butyldimethylsilyloxy-β-amino butanoates and butanamides through enolate formation and alkylation following a tandem (via the (Z)-lithium enolate) or stepwise (via the (E)-lithium enolate) protocol gives a range of separable syn- and anti-α-alkyl-β-amino esters and amides. O-Silyl deprotection of the syn- and anti-α-alkyl-β-amino butanoates with TBAF and concomitant cyclisation provide trans-3-alkyl-4-amino-γ-butyrolactones, consistent with epimerisation to the thermodynamically favoured trans-lactone occurring upon deprotection.
- Abraham, Elin,Cooke, Jason W.B.,Davies, Stephen G.,Naylor, Alan,Nicholson, Rebecca L.,Price, Paul. D.,Smith, Andrew D.
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p. 5855 - 5872
(2008/02/02)
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- METHOD FOR PRODUCING HEXAHYDROFUROFURANOL DERIVATIVE
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Disclosed is a method for producing a compound (IV) which comprises a step for obtaining a compound (III) by reacting a compound (I) with a compound (II) in the presence of an optionally substituted cyclic secondary amine, and a step for obtaining the compound (IV) by removing R1 and R2 from the compound (III) sequentially or at a time and then cyclizing the compound from which the R1 and R2 are removed. Also disclosed is a method for producing a high-purity compound (IV), an intermediate thereof, and a method for producing the intermediate.
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Page/Page column 29-30
(2008/06/13)
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- Single diastereomers of polyhydroxylated 9-Oxa-1-azabicyclo[4.2.1]nonanes from intramolecular 1,3-dipolar cycloaddition of ω-unsaturated nitrones
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8-Benzyloxymethyl-3,4,5-tribenzoyloxy-9-oxa-1-azabicyclo[4.2.1]nonane has been prepared as the single diastereoisomer 8 from an intramolecular 1,3-dipolar cycloaddition involving 2-(benzyloxy)acetaldehyde and ω-unsaturated hydroxylamine 7 derived from methyl α-D-glucopyranoside. The analogous 8-methoxycarbonyl 9-oxa-1-azabicyclo[4.2.1]nonane was afforded in a similar manner, from methyl D-galactopyranoside and methyl glyoxylate, as a 3:1 mixture of diastereoisomers 15 and 16. When conducted in achiral ionic liquid 17 this ratio increased to 8:1, and in chiral ionic liquid 18, compound 15 was formed exclusively.
- Padar, Petra,Bokros, Attila,Paragi, Gabor,Forgo, Peter,Kele, Zoltan,Howarth, Nicola M.,Kovacs, Lajos
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p. 8669 - 8672
(2007/10/03)
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- Ester dienolate [2,3]-Wittig rearrangement in natural product synthesis: Diastereoselective total synthesis of the triester of viridiofungin A, A 2, and A4
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An ester dienolate [2,3]-Wittig rearrangement was utilized to access the alkylated citric acid skeleton 6 that is characteristic for the viridiofungins and other members of the alkyl citrate family of secondary natural products. The [2,3]-sigmatropic rearrangement of (Z,Z)-15 provided the rearrangement product (±)-syn-16 in moderate yield and with very good diastereoselectivity. A Julia-Kocienski olefination efficiently served to connect the polar head (±)-syn-26 with the lipophilic tail (32a-c) of the viridiofungins. Amide formation between the racemic viridiofungin precursors 35a-c and the enantiomerically pure amino acid L-tyrosine methyl ester followed by preparative reversed-phase HPLC provided the isopropyl dimethyl ester of viridiofungin A ((+)-39a), A2 ((+)-39b), and A4 ((+)-39c) as well as the nonnatural diastereomers (-)-38a-c.
- Pollex, Annett,Millet, Agnes,Mueller, Jana,Hiersemann, Martin,Abraham, Lars
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p. 5579 - 5591
(2007/10/03)
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- Aza-cope rearrangement-Mannich cyclizations for the formation of complex tricyclic amines: Stereocontrolled total synthesis of (±)-gelsemine
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A detailed examination of the use of aza-Cope rearrangement-Mannich cyclization sequences for assembling the azatricyclo[4.4.0.02,8] decane core of gelsemine is described. Iminium ions and N-acyloxyiminium ions derived from endo-oriented 1-methoxy- or 1-hydroxybicyclo[2.2.2]oct-5-enylamines do not undergo the first step of this sequence, cationic aza-Cope rearrangement, to form cis-hydroisoquinolinium ions. However, the analogous base-promoted oxy-aza-Cope rearrangement does take place to form cis-hydroisoquinolones containing functionality that allows iminium ions or N-acyloxyiminium ions to be generated regioselectively in a subsequent step. Mannich cyclization of cis-hydroisoquinolones prepared in this way efficiently assembles the azatricyclo[4.4.0.02,8]decane unit of gelsemine. Using a sequential base-promoted oxy-aza-Cope rearrangement/Mannich cyclization sequence, gram quantities of azatricyclo[4.4.0.02,8]decanone 18, a central intermediate in our total of (±)-gelsemine, were prepared from 3-methylanisole in 12 steps and 16% overall yield.
- Earley, William G.,Jacobsen, Jon E.,Madin, Andrew,Meier, G. Patrick,O'Donnell, Christopher J.,Oh, Taeboem,Old, David W.,Overman, Larry E.,Sharp, Matthew J.
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p. 18046 - 18053
(2007/10/03)
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- Technical production of aldehydes by continuous bleach oxidation of alcohols catalyzed by 4-hydroxy-TEMPO
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Aldehydes can be easily prepared from the corresponding alcohols in good to excellent yields by oxidation with technical bleach and catalytic amounts of 4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxyl (1b, 4-hydroxy TEMPO, "HOT"). Whereas the well-known batch process performed on lab scale is not suitable for the technical synthesis especially of activated β-substituted aldehydes, this transformation can be performed continuously in a simple tube reactor. This layout meets all requirements necessary for the process, i.e., turbulent mixing of the biphasic mixture, removal of heat, short contact times, and high output. Thus, a single tube of 3 mm diameter renders about 60 mol of aldehyde per day.
- Fritz-Langhals, Elke
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p. 577 - 582
(2012/12/25)
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- Preparation of homoallylic homopropargylic alcohols from 2-vinyloxiranes
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(Chemical Equation Presented) β,γ-Unsaturated aldehydes generated in situ by treatment of 2-vinyloxiranes with a catalytic amount of Sc(OTf)3 or BF·OEt2 are effectively trapped by B-allenyl-9-BBN to afford homoallylic homopropargylic alcohols in high yield. An enantioselective version has been demonstrated, and a convenient synthesis of 9-allenyl-9-BBN is described.
- Maddess, Matthew L.,Lautens, Mark
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p. 3557 - 3560
(2007/10/03)
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- NITRONE COMPOUNDS PRODRUGS AND PHARMACEUTICAL COMPOSITIONS OF THE SAME TO TREAT HUMAN DISORDERS
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Disclosed are aryl, heteroaromatic and bicyclic aryl nitrone compounds and pharmaceutical compositions containing such derivatives. The disclosed compositions are useful for preventing and/or treating pain, neurodegenerative, autoimmune and inflammatory diseases or conditions in mammals.
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Page/Page column 47
(2008/06/13)
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- Synthesis of diastereomerically and enantiomerically pure 2,3-disubstituted tetrahydrofurans using a sulfoxonium ylide
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Nucleophilic substitution reactions of 2,3-epoxy alcohols, easily prepared via Sharpless asymmetric epoxidation chemistry, offer access to a wide variety of enantiomerically pure compounds. In this communication, we describe the use of a Payne rearrangement to control regioselectivity in the ring-opening of a series of 2,3-epoxy alcohols with dimethylsulfoxonium methylide to yield diastereomerically and/or enantiomerically pure disubstituted tetrahydrofuran rings. The factors influencing the success and substitution pattern of the THF ring products are discussed, including steric, electronic, and solvent effects. Copyright
- Schomaker, Jennifer M.,Pulgam, Veera Reddy,Borhan, Babak
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p. 13600 - 13601
(2007/10/03)
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