13 results match your criteria Arkivoc[Journal]

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When nucleoside chemistry met hypervalent iodine reagents.

ARKIVOC 2018 21;2018(Pt II):252-279. Epub 2017 Dec 21.

Department of Chemistry & Biochemistry, The City College of New York, 160 Convent Avenue, New York, NY 10031, USA, and The Ph.D. Program in Chemistry, The Graduate Center of the City University of New York, New York, NY 10016, USA.

There has been increasing use of hypervalent iodine reagents in the field of nucleoside chemistry. Applications span: (a) synthesis of nucleoside analogues with sulfur and seleno sugar surrogates, (b) synthesis of unusual carbocyclic and ether ring-containing nucleosides, (c) introduction of sulfur and selenium into pyrimidine bases of nucleosides and analogues, (d) synthesis of isoxazole and isoxazoline ring-containing nucleoside analogues, (e) involvement of purine ring nitrogen atoms for remote C-H bond oxidation, and (f) metal-catalyzed and uncatalyzed synthesis of benzimidazolyl purine nucleoside analogues by intramolecular C-N bond formation. This review offers a perspective on developments involving the use of hypervalent iodine reagents in the field of nucleoside chemistry that have appeared in the literature in the 2003-2017 time frame. Read More

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http://dx.doi.org/10.24820/ark.5550190.p010.281DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6135263PMC
December 2017
2 Reads

New cytotoxic cyclic peroxide acids from sp. marine sponge.

ARKIVOC 2015;2015(5):164-175. Epub 2015 Apr 5.

Department of Chemistry, Faculty of Science, King Abdulaziz University, P.O. Box 80203, Jeddah 21589, Saudi Arabia; Department of Chemistry, Faculty of Science, Damietta University, Damietta, Egypt.

Bioassay-guided fractionation of the extract of Jamaican marine sponge sp. followed by preparative TLC and HPLC yielded several known methyl ester cyclic peroxides (), known plakortides (), known bicyclic lactone () and new cyclic peroxide acids (). The chemical structures were elucidated by extensive interpretation of their spectroscopic data. Read More

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http://dx.doi.org/10.3998/ark.5550190.p008.948DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4732738PMC
April 2015
9 Reads

The [5+5] route to the phenanthrene skeleton.

ARKIVOC 2016 21;2016(1):276-306. Epub 2016 Jun 21.

Department of Chemistry and Biochemistry, New Mexico State University, Las Cruces, New Mexico, 88003, USA.

This account describes the historical development of the coupling of γ,δ-unsaturated Fischer carbene complexes and -alkynylbenzaldehydes, which directly affords hydrophenanthrene ring systems in a process where each reactant contributes five carbons to the newly-formed bicyclo[4.4.0]decane ring system. Read More

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http://dx.doi.org/10.3998/ark.5550190.p009.611DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5340207PMC

Novel ynamide structural analogues and their synthetic transformations.

ARKIVOC 2014;2014(1):127-141

This Highlight accounts for a recent phenomenon in which a series of novel ynamide structural analogues have emerged and caught the attention of the synthetic community. Preparations and reactions of these ynamide variants are delineated here to demonstrate their accessibility as well as their reactivity. This Highlight should help reveal that these unique N-containing alkynes can become highly versatile building blocks in organic syntheses. Read More

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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4535823PMC
January 2014
3 Reads

Formal synthesis of the bisbenzylisoquinoline alkaloid berbamunine by asymmetric substitution of chiral organolithium compounds.

ARKIVOC 2011 Jan;2011(Pt 5):167-179

Department of Chemistry and Biochemistry, University of Arkansas, Fayetteville, AR 72701, U.S.A.

Asymmetric alkylation of enantiomeric tetrahydroisoquinolyl oxazolines was achieved with 96-97% diastereoselectivity. Removal of the oxazoline chiral auxiliary and further transformations provide a straightforward synthesis of the two synthetic intermediates that were previously synthesized by resolution, and which comprise a formal synthesis of berbamunine by Ullman coupling. Read More

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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3192450PMC
January 2011
5 Reads

Modulation of an n→π* interaction with α-fluoro groups.

ARKIVOC 2010 Jul;2010:251-262

Noncovalent interactions play an essential role in biological and chemical processes. In the main chain of common protein secondary structures, the lone pair (n) of a carbonyl oxygen is delocalized into the antibonding orbital (π*) of the subsequent carbonyl group. Herein, experimental and computational data reveal that this n→π* interaction can be attenuated by the inductive electron withdrawal of one or two α-fluoro groups in the donor. Read More

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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3107012PMC
July 2010
2 Reads

Pseudomonas aeruginosa porphobilinogen synthase assembly state regulators: hit discovery and initial SAR studies.

ARKIVOC 2010 Jun;2010:175-188

Fox Chase Chemical Diversity Center, Inc., Pennsylvania Center for Drug Discovery, Pennsylvania Biotechnology Center, Doylestown, PA 18902 USA.

Porphobilinogen synthase (PBGS) catalyzes the first common step in the biosynthesis of the essential heme, chlorophyll and vitamin B(12) heme pigments. PBGS activity is regulated by assembly state, with certain oligomers exhibiting biological activity and others either partially or completely inactive, affording an innovative means of allosteric drug action. Pseudomonas aeruginosa PBGS is functionally active as an octamer, and inactive as a dimer. Read More

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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3106444PMC
June 2010
55 Reads

Synthesis of cycloheptanoid natural products via tandem 5-exo cyclization/Claisen rearrangement process.

Authors:
Timo V Ovaska

ARKIVOC 2011 31;2011(5):34-44. Epub 2010 Oct 31.

Department of Chemistry, Connecticut College, 270 Mohegan Avenue, New London, CT 06320,

This article describes the development of microwave-assisted oxyanionic 5-exo-dig cyclization-Claisen rearrangement sequence as a convenient "one-pot" route to a variety of seven-membered carbocyclic ring systems. This process was used as the key transformation for the construction of several natural products, including frondosins A, B, and C. Read More

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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3327132PMC
October 2010

Cascade carbopalladation-annulation approach toward polycylic derivatives of indole and indolizine.

ARKIVOC 2010 Dec;2011(5):76-91

A convenient method for construction of polycyclic fused nitrogen-containing heterocycles has been developed. The methodology involves palladium-catalyzed intermolecular carbopalladation-annulation cascade reaction of haloaryl heterocyclic derivatives with different alkynes under relatively mild reaction conditions. Thus, the palladium-catalyzed cascade cyclization of bromophenyl derivatives of indolizine and indole with alkynes afforded tetracycles, possessing a newly formed fused six-membered ring. Read More

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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3909657PMC
December 2010
6 Reads

Syntheses of protoporphyrin-IX derivatives bearing extended propionate side-chains.

ARKIVOC 2009 May;2010(5):5-16

In order to investigate the relationship between depth within membranes of singlet oxygen generation and effectiveness of photodynamic therapy of tumors, analogs of protoporphyrin-IX 1 bearing five 4 and seven 5 carbon atoms (in place of the 3-carbon atom chain in 1) were synthesized from monopyrrole precursors. Read More

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http://dx.doi.org/10.1901/jaba.2009.2010-5DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2783647PMC
May 2009
2 Reads

Fluorous Mixture Synthesis (FMS) of Enantiomers, Diastereomers, and Compound Libraries.

Authors:
Wei Zhang

ARKIVOC 2004 May;i:101-109

Fluorous Technologies, Inc. University of Pittsburgh Applied Research Center, 970 William Pitt Way Pittsburgh, PA 15238, USA E-Mail:

Fluorous mixture synthesis (FMS) is a newly developed highly-efficient solution-phase technology. A set of substrates attached to homologous fluorous tags is mixed and taken through a sequence of organic reactions. The final mixtures are demixed by fluorous HPLC and detagged to give individually pure final products. Read More

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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2387003PMC

Approximate H(5) Ring Conformation of 2,3-O-Carbonate Protected α- and β-L-Rhamnopyranosides as Confirmed by X-Ray Crystallography.

ARKIVOC 2005 Aug;2005(6):339-344

2,3-O-Carbonate protected rhamnopyranosides with both the α- and β-anomeric configuration are shown crystallographically to have ring conformations that differ significantly from the chair and which approach the (o)H(5) half-chair. This distortion, which is greatest in the α-anomer, provides a basis for the α-selectivity of 2,3-O carbonate protected manno- and rhamnopyranosyl donors as well as the conformationally related 2,3-O-alkylidene derivatives, in homogeneous solution phase glycosylation reactions. Read More

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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2386999PMC
August 2005
1 Read

An improved synthesis for the (Z)-14-methyl-9-pentadecenoic acid and its topoisomerase I inhibitory activity.

ARKIVOC 2007 ;2007(viii):49-57

An improved synthesis for the (Z)-14-methyl-9-pentadecenoic acid was developed based on the appropriate use of (trimethylsilyl)acetylene as the key reagent in the synthesis. The reported synthesis started with commercially available 8-bromo-1-octanol and furnished the desired acid in seven steps and in a 16% overall yield, a significant improvement over the previous reported synthesis for this fatty acid. The synthesis reported herein afforded sufficient amounts to study the acid topoisomerase I inhibitory potential and it was found that the title acid inhibits the human placenta DNA topoisomerase I enzyme at concentrations of 500 μM. Read More

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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1939943PMC
January 2007
7 Reads
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