- Synthesis of treprostinil: Key claisen rearrangement and catalytic pauson-khand reactions in continuous flow
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A new synthesis of treprostinil is described using a plug flow reactor in two of the key steps. First, a Claisen rearrangement reaction is described in scaled flow at multigram amounts. Yields and selectivity of this step are sharply improved compared to those from previous syntheses. Second, the key Pauson-Khand reaction in flow is described under catalytic conditions with 5 mol% of cobalt carbonyl and only 3 equiv. of CO. Scaling up of this reaction safely ensures a good yield of an advanced intermediate which is transformed into treprostinil in three steps. Other improvements are the introduction of the carboxymethyl chain into the phenol from the beginning to reduce the protection-deprotection steps. The synthesis is completed in 14% global yield after 12 linear steps from (S)-epichlorhydrin.
- García-Lacuna, Jorge,Domínguez, Gema,Blanco-Urgoiti, Jaime,Pérez-Castells, Javier
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Read Online
- TBuO 2H/Cu(acac) 2-Mediated Intramolecular Oxidative Lactonization of o -Allyl Arylaldehydes: Synthesis of 1-Oxoisochromans
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A concise route for the tBuO 2H/Cu(acac) 2-mediated synthesis of 1-oxoisochromans is described. This includes: (i) oxidation of oxygenated o -allyl arylaldehydes and (ii) sequential intramolecular lactonization of the resulting olefin-containing benzoic acids. A plausible mechanism is proposed and discussed.
- Chang, Meng-Yang,Lai, Kai-Xiang,Chen, Kuan-Ting
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p. 527 - 537
(2020/10/19)
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- Turn on chemiluminescence-based probes for monitoring tyrosinase activity in conjunction with biological thiols
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We report a chemiluminescent probe (CLPT1) that permits the paired detection of tyrosinase (Tyr) and biological thiols. Tyr only leads to a poor chemiluminescence response, a finding ascribed to the formation of a stableo-benzoquinone intermediate. The addition of glutathione (GSH), or ascorbate to theo-benzoquinone intermediate results in thiol conjugation or reduction to this intermediate, respectively. This produces a strong chemiluminescence response. Thiol co-dependence was demonstrated in live cells using the cell permeable analogue,CLPT3. The present chemiluminescence-based strategy allows the concurrent detection of tyrosinase activity and biological thiols.
- Shelef, Omri,Sedgwick, Adam C.,Pozzi, Sabina,Green, Ori,Satchi-Fainaro, Ronit,Shabat, Doron,Sessler, Jonathan L.
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supporting information
p. 11386 - 11389
(2021/11/09)
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- Ancillary ligands switch the activity of Ru–NHC-based oxidation precatalysts
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Herein we demonstrate how the inner-sphere coordinating ligands switch the activity of Ru–NHC-based oxidation precatalysts in the oxidative conversion of olefins to carbonyl compounds, with the help of a series of systematically varied imidazolydene-NHC (Im-NHC) and triazolydene-NHC (Tz-NHC)-based ruthenium(II)-complexes. It is shown that the catalytic activity of the para-cymene-containing precatalysts varies in the order of [(Tz-NHC)Ru(para-cymene)Cl]+ > [(Im-NHC)Ru(para-cymene)Cl]+, while the order of activity of the MeCN-containing precatalysts is found to be reversed, i.e., [(Im-NHC)Ru(MeCN)4]2+ > [(Tz-NHC)Ru(MeCN)4]2+. Along with the electronic influence of the NHC ligands, the effect of the lability of the para-cymene and MeCN ligands, and the overall charge of the complexes might be attributed toward such a switching of catalytic activity. This finding led to develop a new precatalyst with improved activity which was further utilized in selective oxidation of a series of styrene substrates containing other oxidation-sensitive functionalities.
- Gupta, Suraj K.,Mandal, Tanmoy,Gangber, Tejaswinee,Singh, Vivek,Choudhury, Joyanta
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supporting information
(2019/10/28)
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- PdCl2/CuCl2/Bi(OTf)3-promoted Construction of Sulfonyl Dibenzooxabicyclo[3.3.1]nonanes and Arylnaphthalenes via Intramolecular Annulation of Sulfonyl o-Allylarylchromanones
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PdCl2/CuCl2/Bi(OTf)3-promoted intramolecular domino annulation of sulfonyl o-allylarylchromanones provides tetracyclic sulfonyl dibenzooxabicyclo[3.3.1]nonanes and bicyclic arylnaphthalenes with good to excellent yields in MeOH at room (25 °C) and refluxing (65 °C) temperature, respectively. The starting sulfonyl o-allylarylchromanones can be easily obtained from the intermolecular cyclocondensation of α-sulfonyl o-hydroxyacetophenones and o-allylbenzaldehydes. The uses of various catalysts and solvent systems are investigated herein for convenient transformation. A plausible mechanism is proposed and discussed. This protocol provides one-pot ring closure via carbon-carbon (C?C) bond formation. (Figure presented.).
- Chang, Meng-Yang,Hsueh, Nai-Chen
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supporting information
p. 5736 - 5750
(2020/12/01)
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- Visible-light mediated facile dithiane deprotection under metal free conditions
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Visible light mediated facile and selective dithiane deprotection under metal free conditions is developed. Eosin Y (1 mol%) proved to be an effective catalyst for the dithiane deprotection under the ambient photoredox conditions. The standard household compact fluorescent light source (CFL bulb) proved to be effective under open-air conditions in aqueous acetonitrile at room temperature. The protocol that exhibits a broad substrate scope and functional group tolerance has been shown to expand to a range of transformations for the electron-rich and -deficient thioacetals and thioketals. The synthetic utility of this protocol has also been demonstrated by gram-scale application.
- Dharpure, Pankaj D.,Bhowmick, Anindita,Warghude, Prakash K.,Bhat, Ramakrishna G.
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- A molybdenum based metallomicellar catalyst for controlled and chemoselective oxidation of activated alcohols in aqueous medium
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A surfactant based oxodiperoxo molybdenum complex, which could activate molecular oxygen, has been employed as a catalyst for controlled oxidation of benzylic alcohols to corresponding carbonyls. The oxidation reactions were carried out under aqueous environment, however, in the absence of any extraneous base or co-catalyst. Sensitive/oxidizable functional groups like cyano, sulfide, hydroxyl, aryl-hydroxyl, alkene (internal/terminal), alkyne (internal/terminal), and acetal were tolerated during the transformations. Such selectivity is attributed to the mild nature of the catalyst. The methodology could also be scaled-up for multi-gram synthesis and the protocol is likely to find practical use since it requires an inexpensive recyclable-catalyst and easily available oxidant (under green conditions). A plausible mechanism is proposed with the help of preliminary computational study.
- Thiruvengetam, Prabaharan,Chakravarthy, Rajan Deepan,Chand, Dillip Kumar
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p. 123 - 133
(2019/07/19)
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- Coordination Booster-Catalyst Assembly: Remote Osmium Outperforming Ruthenium in Boosting Catalytic Activity
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Presented herein is a set of bimetallic and trimetallic “coordination booster-catalyst” assemblies in which the coordination complexes [RuII(terpy)2] and [OsII(terpy)2] acted as boosters for enhancement of the catalytic activity of [RuII(NHC)(para-cymene)]-based catalytic site. The boosters accelerated the oxidative loss of para-cymene from the catalytic site to generate the active catalyst during the oxidation of alkenes and alkynes into corresponding aldehydes, ketones and diketones. It was found that the boosting efficiency of the [OsII(terpy)2] units was considerably higher than its congener [RuII(terpy)2] unit in these assemblies. Mechanistic studies were conducted to understand this unique improvement.
- Mandal, Tanmoy,Singh, Vivek,Choudhury, Joyanta
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supporting information
p. 4774 - 4779
(2019/11/11)
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- Diethylaminosulfur Trifluoride (DAST)-Mediated Intramolecular Benzannulation of o-Allylchalcones: Synthesis of 3-Fluorotetralins
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A concise route for the synthesis of 3-fluorotetralines is described, including: (i) NaBH 4 -mediated reduction of oxygenated o -allylchalcones and (ii) sequential DAST-mediated intramolecular annulation of the resulting alkenols. A plausible m
- Chang, Meng-Yang,Chen, Han-Yu,Tsai, Yu-Lin
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p. 2553 - 2563
(2019/06/08)
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- Synthesis of 3-Azidopiperidine Skeleton Employing Ceric Ammonium Nitrate (CAN)-Mediated Regioselective Azidoalkoxylation of Enol Ether: Total Synthesis of D2 Receptor Agonist (±)-Quinagolide
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The total synthesis of (±)-quinagolide, which is a D2 receptor agonist, was accomplished via a ceric ammonium nitrate (CAN)-mediated regioselective azidoalkoxylation of enol ether route. Key features of the synthesis include Claisen rearrangement, PPTS (pyridinium p-toluenesulfonate)-catalyzed one-pot acetal deprotection, followed by a diastereoselective Henry reaction, which enables construction of the required trans ring junction and CAN-mediated regioselective azidoalkoxylation of enol ether. The PPTS-catalyzed intramolecular diastereoselective Henry reaction to fix three contiguous stereocenters on tetrahydronaphthalene and the first-of-its-kind synthesis of the 3-azidopiperidine skeleton, using a CAN-mediated regioselective azidoalkoxylation of enol ether, are important findings of the present work.
- Chavan, Subhash P.,Kadam, Appasaheb L.,Lasonkar, Pradeep B.,Gonnade, Rajesh G.
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supporting information
p. 7011 - 7014
(2018/11/23)
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- Synthesis of Polysubstituted 3-Methylisoquinolines through the 6π-Electron Cyclization/Elimination of 1-Azatrienes derived from 1,1-Dimethylhydrazine
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A convenient one pot microwave-assisted 6π-electron cyclization/aromatization approach toward 3-methylisoquinolines is reported. The starting 1-azatriene derivatives were prepared in situ by reaction of 2-propenylbenzaldehydes with 1,1-dimethylhydrazine, which exhibited superior performance when compared with other hydrazine derivatives. Minor amounts of the related 3,4-dihydro isoquinolines were formed concomitantly with the isoquinolines, and a mechanism for their generation was proposed. The reaction conditions were optimized, and its scope and limitations were explored. In general, the transformation proceeded in moderate to good yields.
- Vargas, Didier F.,Larghi, Enrique L.,Kaufman, Teodoro S.
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supporting information
p. 5605 - 5614
(2018/10/09)
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- A novel complexity-to-diversity strategy for the diversity-oriented synthesis of structurally diverse and complex macrocycles from quinine
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Recent years have witnessed a global decline in the productivity and advancement of the pharmaceutical industry. A major contributing factor to this is the downturn in drug discovery successes. This can be attributed to the lack of structural (particularly scaffold) diversity and structural complexity exhibited by current small molecule screening collections. Macrocycles have been shown to exhibit a diverse range of biological properties, with over 100 natural product-derived examples currently marketed as FDA-approved drugs. Despite this, synthetic macrocycles are widely considered to be a poorly explored structural class within drug discovery, which can be attributed to their synthetic intractability. Herein we describe a novel complexity-to-diversity strategy for the diversity-oriented synthesis of novel, structurally complex and diverse macrocyclic scaffolds from natural product starting materials. This approach exploits the inherent structural (including functional) and stereochemical complexity of natural products in order to rapidly generate diversity and complexity. Readily-accessible natural product-derived intermediates serve as structural templates which can be divergently functionalized with different building blocks to generate a diverse range of acyclic precursors. Subsequent macrocyclisation then furnishes compounds that are each based around a distinct molecular scaffold. Thus, high levels of library scaffold diversity can be rapidly achieved. In this proof-of-concept study, the natural product quinine was used as the foundation for library synthesis, and six novel structurally diverse, highly complex and functionalized macrocycles were generated.
- Ciardiello,Stewart,Sore,Galloway,Spring
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p. 2825 - 2843
(2017/05/29)
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- PROCESS FOR PREPARATION OF PROSTACYCLIN DERIVATIVES
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Disclosed is an improved method of synthesis for Treprostinil comprising condensation reaction of compound (4) with a hydroxyl-protected alkynol (5) to give the condensation product, compound (6). Subjecting compound (6) to oxidation, reduction, hydroxyl protection and carbonylation, cyclization reactions gives the tricyclic derivative (10). Further reactions comprising reduction, hydrogenation and deprotection of the phenolic and side-chain hydroxyl groups, wherein the sequence and choice of reagents is governed by protecting groups, give the triol intermediate, compound (14). Cyanoalkylation at phenolic hydroxyl functionality and further hydrolysis yields the prostacyclin compound, Treprostinil (1) and its pharmaceutically acceptable salts with desired purity.
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Page/Page column 25
(2017/08/21)
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- Synthesis of cis-enamide macrocycles via ring-closing metathesis
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Herein we report the synthesis of 13-, 14- and 15-membered cyclic lactams, using Grubbs' RCM method in 25, 52 and 46% yields respectively. The cis-enamide functional group was successfully introduced into these cyclic lactams by syn sulfoxide elimination
- Ramírez, Moisés,Ochoa-Terán, Adrián,Somanathan, Ratnasamy,Aguirre, Gerardo
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p. 194 - 209
(2017/06/19)
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- Synthetic methods for phoyunbenes A-D and thunalbene
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Invented is a method for synthesizing thunalbene and phoyunbenes A-D via a Horner-Wadsworth-Emmons (HWE) reaction in a simple and effective way. The compounds of the present invention have shown anti-inflammatory effects in RAW-264.7 macrophage which is induced by lipopolysaccharide.
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Paragraph 0044; 0045
(2017/04/13)
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- Syntheses of phoyunbenes A-D and thunalbene for their anti-inflammatory evaluation
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Simple and efficient first syntheses of phoyunbenes A-D and thunalbene have been developed using Horner- Wadsworth-Emmons reaction as a key step. Later, their anti-inflammatory effects were investigated in lipopolysaccharide-induced RAW-264.7 macrophages. The results revealed that phoyunbenes A-D and thunalbene showed weak inhibitory activities without cytotoxicity on the production of nitric oxide (NO) which is an important inflammatory mediator.
- Moon, Insu,Kim, Jin-Kyung,Jun, Jong-Gab
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p. 2907 - 2914
(2016/01/25)
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- Sodium Perborate: A Facile Catalyst for Allylation of Active Centers
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An efficient and ecofriendly allylation of O-H, N-H, and C-H groups has been achieved successfully with the reaction of allyl bromide by using sodium perborate as a new catalyst in aqueous media. The advantage of this method is operationally simple, short reaction time, good yield, and simple workup conditions over the previously reported conventional methods such as amination, oxyalkylation reactions of allyl bromide, and Friedel-Crafts allylation chemistry.
- Jayaprakash, Soora Harinath,Krishna, Balam Satheesh,Prasad, Sthanikam Siva,Sudha, Sarva Santhi,Reddy, Cirandur Suresh
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supporting information
p. 355 - 362
(2015/10/29)
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- A practical in situ generation of the schwartz reagent. reduction of tertiary amides to aldehydes and hydrozirconation
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A new, highly efficient in situ protocol (Cp2ZrCl2/LiAlH(OBu-t)3) is described for the generation of the Schwartz reagent which provides a convenient method for the amide to aldehyde reduction and the regioselective hydrozirconation-iodination of alkynes and alkenes. Highlighted are chemoselective reductions of benzamides derived by directed ortho metalation (DoM) chemistry, allowing the synthesis of valuable 1,2,3-substituted benzaldehydes. The single-step, three-component process proceeds in a very short reaction time, shows excellent functional group compatibility, and uses inexpensive and long-storage stable reducing reagents.
- Zhao, Yigang,Snieckus, Victor
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supporting information
p. 390 - 393
(2014/04/03)
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- INHIBITORS OF HUMAN IMMUNODEFICIENCY VIRUS REPLICATION
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The disclosure generally relates to compounds of formula I, including compositions and methods for treating human immunodeficiency virus (HIV) infection. The disclosure provides novel inhibitors of HIV, pharmaceutical compositions containing such compounds, and methods for using these compounds in the treatment of HIV infection. Formule (I)
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Page/Page column 99; 100; 124
(2014/10/18)
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- Alkene cleavage by white-rot Trametes hirsuta: Inducing enzyme activity by a fungicide
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Alkene cleavage is a widely employed oxidation reaction in organic chemistry. An enzyme preparation of the wood degrading fungus Trametes hirsuta is known to cleave the CC double bond adjacent to an aromatic ring to give the corresponding carbonyl compound at the expense of molecular oxygen as the sole oxidant. Lab-grown fungus cultures displayed varied activity and lost their alkene cleavage activity over generations of growth. t-Anethole, which is the best accepted substrate by the enzyme, is described as a major component of essential oils produced by certain plants with powerful fungicidal property. We could now show that the alkene cleaving activity was improved by the addition of the fungicide t-anethole during culture growth which represented to be an efficient method to produce cells possessing a consistent level of high alkene cleavage activity.
- Rajagopalan, Aashrita,Seisser, Birgit,Mutti, Francesco G.,Schober, Markus,Kroutil, Wolfgang
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p. 118 - 122
(2013/05/08)
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- MACROCYCLIC INHIBITORS OF FLAVIVIRIDAE VIRUSES
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Provided are compounds of Formula I: and pharmaceutically acceptable salts and esters thereof. The compounds, compositions, and methods provided are useful for the treatment of virus infections, particularly hepatitis C infections.
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Page/Page column 145; 149
(2014/01/08)
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- Synthesis Of Treprostinil And Intermediates Useful Therein
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Treprostinil is prepared by a process which involves Pauson-Khan cyclization of an an alkene-substituted, alkyne-substituted benzene corresponding to formula: (I) where PMB represents para-methoxy benzyl protecting group and R1 and R2 are alcohol protecting groups. Following cyclization, the resulting compound can be subjected to several chemical trans-formations followed by alkylation, hydrolysis and salt formation to yield treprostinil sodium. The use of para-methoxybenzyl group as the phenolic protecting group confers several process advantages that result in simplified purification of the final product and improved yields.
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Paragraph 0032; 0033
(2014/01/08)
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- Expanding the regioselective enzymatic repertoire: Oxidative mono-cleavage of dialkenes catalyzed by Trametes hirsuta
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The first report of a biocatalytic regioselective oxidative mono-cleavage of dialkenes was successfully achieved employing a cell-free enzyme preparation from Trametes hirsuta at the expense of molecular oxygen. Selected reactions were performed on a preparative scale affording high to excellent conversions and chemoselectivities. The Royal Society of Chemistry 2012.
- Paul, Caroline E.,Rajagopalan, Aashrita,Lavandera, Ivan,Gotor-Fernandez, Vicente,Kroutil, Wolfgang,Gotor, Vicente
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p. 3303 - 3305
(2012/04/23)
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- SYNTHESIS OF TREPROSTINIL AND INTERMEDIATES USEFUL THEREIN
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Treprostinil is prepared by a process which involves Pauson - Khan cyclization of an an alkene-substituted, alkyne-substituted benzene corresponding to formula : (I) where PMB represents para-methoxy benzyl protecting group and R1 and R2 are alcohol protecting groups. Following cyclization, the resulting compound can be subjected to several chemical transformations followed by alkylation, hydrolysis and salt formation to yield treprostinil sodium. The use of para-methoxybenzyl group as the phenolic protecting group confers several process advantages that result in simplified purification of the final product and improved yields.
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Page/Page column 9-10
(2012/02/05)
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- PROTECTED ALDEHYDES FOR USE AS INTERMEDIATES IN CHEMICAL SYNTHESES, AND PROCESSES FOR THEIR PREPARATION
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A para-methoxy protected benzaldehyde useful in preparation of treprostinil, and of formula:(Formula (1)) is prepared by subjecting to Claisen re-arrangement a substituted benzaldehyde of formula (la): (Formula (Ia)) to form the m-hydroxy-substituted benz
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Page/Page column 6
(2012/02/05)
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- Synthesis of 1-indanonyl oxepanes
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A variety of 1-indanonyl oxepanes with the novel structure of indanonyl oxepanes was prepared from reaction of hydroxybenzaldehydes via a series of reasonable transformations, including the regioselective PhBClmediated allylation (or Claisen rearrangement), one-pot reaction of ring-closing metathesis and the Wittig olefination, hydrogenation, and the Friedel-Crafts intramolecular cyclization. Georg Thieme Verlag Stuttgart . New York.
- Chang, Meng-Yang,Lee, Nien-Chia
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scheme or table
p. 867 - 872
(2012/06/01)
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- Facile synthesis of substituted isoquinolines
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A facile three-step protocol toward methoxy isoquinolines 7 starting with substituted 2-allylbenzaldehydes 9 was described. The overall synthetic process of skeleton 7 was carried out using the Grignard addition, PCC-oxidation, and one-pot oxidative cleavage of the olefinic group of skeleton 9 with OsO 4-NaIO4 followed by the condensation of the resulting 1,5-dicarbonyl compounds with NH4OAc. Skeleton 9 was prepared in high yield via the known Claisen rearrangement of skeleton 8 and O-methylation. Papaverine 2 is also synthesized via the simple three-step synthetic protocol.
- Chang, Meng-Yang,Wu, Ming-Hao,Lee, Nein-Chia,Lee, Ming-Fang
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scheme or table
p. 2125 - 2128
(2012/07/14)
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- Schwartz Reagents: Methods of In Situ Generation and Use
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Embodiments of the invention provide a method of using Schwartz Reagent, Cp2Zr(H)Cl, without accumulating or isolating it. Methods provide mixtures of Cp2ZrCl2, reductants that selectively reduce Cp2ZrCl2, and substrates. After reaction of Cp2ZrCl2 and the reductant, an intermediate reduction product is formed, apparently Schwartz Reagent. The in situ Schwartz Reagent then selectively reduces certain functional groups on the substrate. Substrates include tertiary amides, tertiary benzamides, aryl O-carbamates, and heteroaryl N-carbamates, which are reduced to aldehydes, benzaldehydes, aromatic alcohols, and heteroaromatics, respectively. Compared to prior methods, reagents are inexpensive and stable, reaction times are short, and reaction temperature in certain cases is conveniently room temperature. It has been estimated that using the in situ method described herein instead of synthesized or commercially obtained Schwartz Reagent provides a 50% reduction in cost.
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Page/Page column 16
(2010/06/19)
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- NOVEL SULFONE AMIDE DERIVATIVES CAPABLE OF INHIBITING BACE
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The present invention relates to novel derivatives of sulfone amide of Formula 1 as defined in this disclosure which inhibit the activity of BACE (or beta-secretase). These sulfone amide derivatives are useful for the treatment and prevention of Alzheimer's disease and related diseases caused by production of beta-amyloid, by inhibiting the activity of BACE.
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Page/Page column 189-190
(2010/02/11)
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- Mild and eco-friendly oxidative cleavage of 1,3-dithianes and 1,3-dithiolanes with a catalytic amount of hydrobromic acid and hydrogen peroxide: Synergetic effect of bromonium ion equivalent and hydrogen peroxide
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A combination of a catalytic amount hydrobromic acid (10 mol%) and an excess of hydrogen peroxide is found to be an effective reagent for expeditious regeneration of carbonyl compounds from their 1,3-dithiane as well as 1,3-dithiolane derivatives. Absence of nuclear bromination of aromatic substrates and overoxidation of regenerated oxidation-prone aromatic aldehydes, compatibility with a number of functional groups, such as amino, hydroxy, acetoxy, methylenedioxy and useful phenol-protecting allyl, benzyl and TBDMS ethers, benzoate esters and amino-protecting Cbz carbamate and N-benzylamine (NHBn) moieties are the advantageous features of this protocol.
- Ganguly, Nemai C.,Datta, Mrityunjoy
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p. 218 - 221
(2007/10/03)
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- The synthesis of ventiloquinone L, the monomer of cardinalin 3
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Readily available ethyl-4-acetoxy-6,8-dimethoxynaphthalene-2-carboxylate 27 was converted into 1 -[3-allyl-4(benzyloxy)-6,8-dimethoxy-2-naphthyl)-1-ethanol 31 in seven steps. Subjection of this compound to Wacker oxidation conditions provided 5-benzyloxy-
- Mmutlane, Edwin M.,Michael, Joseph P.,Green, Ivan R.,De Koning, Charles B.
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p. 2461 - 2470
(2007/10/03)
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- Ecofriendly solid-state oxidative deprotection of 1,3-dithianes and 1,3-dithiolanes using ammonium persulfate on wet montmorillonite K-10 clay support under microwave irradiation
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Solid-state microwave-assisted oxidative deprotection of 1,3-dithianes and 1,3-dithiolanes of aromatic aldehydes and ketones, cyclic ketones, α,β-unsaturated aldehydes and aliphatic aldehydes and ketones has been accomplished using ammonium persulfate on wet montmorillonite K-10 clay support.
- Ganguly, Nemai C.,Datta, Mrityunjoy
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p. 659 - 662
(2007/10/03)
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- A simple, efficient and general procedure for acetalization of carbonyl compounds and deprotection of acetals under the catalysis of indium(III) chloride
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Indium (III) chloride efficiently catalyzes the protection of a variety of aldehydes and ketones to their corresponding 1,3-dioxolanes and dialkyl acetals in refluxing cyclohexane. On the other hand, deprotection of acetals is also achieved in refluxing aqueous methanol under the catalysis of indium(III) chloride.
- Ranu, Brindaban C.,Jana, Ranjan,Samanta, Sampak
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p. 446 - 450
(2007/10/03)
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- Antimycobacterial activity of 5-arylidene derivatives of hydantoin
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The synthesis of various 5-arylidene-2-thiohydantoins and results of the primary assay in vitro for their antimycobacterial activity is reported. Eight of those compounds exhibited >90% inhibition of Mycobacterium tuberculosis growth and for them the minimum inhibitory concentrations, cytotoxicity (IC50) and the selectivity index values were determined. The most active structure, (5Z)-5-(1,1′-biphenyl-4-ylmethylene)-2-thioxoimidazolidin-4-one, showed MIC=0.78 μg/ml. For all compounds logP and logD (pH 6.5) values were calculated.
- Kiec-Kononowicz,Szymanska
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p. 909 - 916
(2007/10/03)
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- A mild deprotection strategy for allyl-protecting groups and its implications in sequence specific dendrimer synthesis
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A mild deprotection strategy for allyl ethers under basic conditions in the presence of a palladium catalyst is described. Under these conditions, aryl allyl ethers can be cleaved selectively in the presence of alkyl allyl ethers. These conditions are also effective in the deprotection of allyloxycarbonyl groups. The utility of the current methodology in sequence specific dendrimer synthesis is demonstrated.
- Vutukuri, Dharma Rao,Bharathi, Pandi,Yu, Zhouying,Rajasekaran, Karthik,Tran, My-Huyen,Thayumanavan
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p. 1146 - 1149
(2007/10/03)
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- Trisubstituted-N-[(1S)-1,2,3,4-tetrahydro-1-naphthalenyl] benzamides which inhibit P2X3 and P2X2/3 containing receptors
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Compounds of formula (I) are novel P2X3 and P2X2/P2X3 antagonists which are useful in treating pain, urinary incontinence and bladder overactivity.
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- Solid- and solution-phase synthesis of vancomycin and vancomycin analogues with activity against vancomycin-resistant bacteria
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Vancomycin, the prototypical member of the glycopeptide family of antibiotics, is a clinically used antibiotic employed against a variety of drug-resistant bacterial strains including methicillin-resistant Staphylococcus aureus (MRSA). The recent emergence of vancomycin resistance, viewed as a growing threat to public health, prompted us to initiate a program aimed at restoring the potency of this important antibiotic through chemical manipulation of the vancomycin structure. Herein, we describe the development of synthetic technology based on the design of a novel selenium safety catch linker, application of this technology to a solid-phase semisynthesis of vancomycin, and the solid- and solution-phase synthesis of vancomycin libraries. Biological evaluation of these compound libraries led to the identification of a number of in vitro highly potent antibacterial agents effective against vancomycin-resistant bacteria. In addition to aiding these investigations, the solid-phase chemistry described herein is expected to enhance the power of combinatorial chemistry and facilitate chemical biology and medicinal chemistry studies.
- Nicolaou,Cho, Suk Young,Hughes, Robert,Winssinger, Nicolas,Smethurst, Christian,Labischinski, Harald,Endermann, Rainer
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p. 3798 - 3823
(2007/10/03)
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- Development of a novel hapten for radioimmunoassay of the lignan, enterolactone in plasma (Serum). Total synthesis of (±)-trans-5- carboxymethoxyenterolactone and several analogues
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A recently developed method for the analysis of the mammalian lignan, enterolactone 1, is based on time-resolved fluoroimmunoassay (TR-FIA) using an europium chelate as a label. This RIA utilizes enterolactone derivatives carrying a carboxylic acid appendage for the production of antiserum and tracer. The synthesis of 5-carboxymethoxyenterolactone 6 and analogues 5, 7 and 8 is described, and their suitability for the method are discussed. (C) 2000 Elsevier Science Ltd.
- M?kel?, Taru,Matikainen, Jorma,W?h?l?, Kristiina,Hase, Tapio
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p. 1873 - 1882
(2007/10/03)
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- A SIMPLE AND EFFICIENT METHOD FOR PREPARATION OF ALLYL ARYL ETHERS VIA POLYMER SUPPORTED REAGENTS
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Allyl aryl ethers were synthesized in excellent yields and in a state of high purity by reaction of polymer-supported phenoxide ions with allyl bromide in ethanol at room temperature.
- Salunkhe, M.M.,Thorat, M.T.,Mane, R. B.,Sande, A.R.,Wadgaonkar, P.P.
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p. 691 - 694
(2007/10/02)
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