92 results match your criteria Synthesis[Journal]


Formal (4+1)-Cyclization of Ammonium Ylides with Vinylogous para-Quinone Methides.

Synthesis (Stuttg) 2018 Oct 5;50(20):4047-4054. Epub 2018 Sep 5.

Institute of Organic Chemistry, Johannes Kepler University Linz, Altenberger Straße 69, 4040 Linz, Austria.

The formal (4+1)-cyclization between in situ generated achiral carbonyl-stabilized ammonium ylides and vinylogous p-quinone methides can be carried out under operationally simple conditions, leading to two different double bond regioisomers depending on the used conditions. Besides these racemic approaches, also a first proof-of-concept for enantioselective versions of these reactions has been obtained. Read More

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October 2018
2 Reads

Vinylation of Benzylic Amines via C-N Bond Functionalization of Benzylic Pyridinium Salts.

Synthesis (Stuttg) 2018 Aug 8;50(16):3231-3237. Epub 2018 Jun 8.

Department of Chemistry and Biochemistry, University of Delaware, 19716, USA.

Cross-couplings of benzylic pyridinium salts and vinylboronic acids or esters have been developed. Via these benzylic pyridinium intermediates, benzylic amines can be engaged in these cross-couplings via C-N bond functionalization. This method boasts mild reaction conditions and excellent tolerance for heteroaryl substituents and a range of functional groups. Read More

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August 2018
1 Read

Lewis Acid Mediated Cyclizations: Diastereoselective Synthesis of Six- to Eight-Membered Substituted Cyclic Ethers.

Synthesis (Stuttg) 2017 Sep 25;49(18):4229-4246. Epub 2017 Jul 25.

Department of Chemistry, Purdue University, 560 Oval Drive, West Lafayette, IN, 47907, USA.

Cyclic ethers are widely abundant in natural products. Cyclic ether templates are also utilized in drug design and medicinal chemistry. Although the synthetic processes for this class of compounds have been studied extensively with respect to five- and six-membered rings, medium-sized cyclic ethers are synthetically more challenging due to a variety of factors. Read More

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September 2017

Synthesis of 2-Alkenyl-Tethered Anilines.

Synthesis (Stuttg) 2017 Jul 4;49(13):2873-2888. Epub 2017 May 4.

Roger Adams Laboratory, Department of Chemistry, University of Illinois, Urbana, IL 61801, USA.

Three general routes for the synthesis of ()-2-alkenyl-tethered anilines have been developed. The first route involves a 3-aza-Cope rearrangement of -allylic anilines in the presence of a Lewis acid. The requisite -allylic anilines were prepared by the addition of vinyl-magnesium reagents to the corresponding aldimines. Read More

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Remote C-H Functionalization via Selective Hydrogen Atom Transfer.

Synthesis (Stuttg) 2018 Apr 12;50(8):1569-1586. Epub 2018 Feb 12.

Department of Chemistry and Biochemistry, The Ohio State University, Columbus, Ohio, 43210, USA.

The selective functionalization of remote C-H bonds via intramolecular hydrogen atom transfer (HAT) is transformative for organic synthesis. This radical-mediated strategy provides access to novel reactivity that is complementary to closed-shell pathways. As modern methods for mild generation of radicals are continually developed, inherent selectivity paradigms of HAT mechanisms offer unparalleled opportunities for developing new strategies for C-H functionalization. Read More

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April 2018
2 Reads

Scalable Synthesis of Hydrido-Disiloxanes from Silanes: A One-Pot Preparation of 1,3-Diphenyldisiloxane from Phenylsilane.

Synthesis (Stuttg) 2018 Jan 26;50(2):278-281. Epub 2017 Sep 26.

University of Minnesota, Department of Medicinal Chemistry, Weaver-Densford Hall, 308 Harvard St. SE Minneapolis, MN 55455, USA.

A simple, one-pot, and high-yielding synthesis of 1,3-diphenyldisiloxane is presented. The preparation of similar symmetrical disiloxane materials is also accomplished with this same protocol. This mechano-chemical procedure is efficient and highly scalable, furnishing a convenient route to hydrido-disiloxanes from widely accessible commercially available silanes. Read More

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January 2018
1 Read

A general protocol for radical anion [3 + 2] cycloaddition enabled by tandem Lewis acid photoredox catalysis.

Synthesis (Stuttg) 2018 19;50(3):539-547. Epub 2017 Oct 19.

Department of Chemistry, University of Wisconsin-Madison, 1101 University Avenue, Madison, WI 53706 USA.

We report herein a method for intermolecular [3 + 2] cycloaddition between aryl cyclopropyl ketones and alkenes involving the combination of Lewis acid and photoredox catalysis. In contrast to other more common methods for [3 + 2] cycloaddition, these conditions operate using a broad range of both electron-rich and electron-deficient reaction partners. The critical factors predicting the success of these reactions is the redox potential of the cyclopropyl ketone and the ability of the alkene to stabilize a key radical intermediate. Read More

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October 2017
3 Reads

1,3,4-Oxadiazole and Heteroaromatic-Fused 1,2,4-Triazole Synthesis using Diverted Umpolung Amide Synthesis.

Synthesis (Stuttg) 2017 Oct 7;49(20):4670-4675. Epub 2017 Aug 7.

Department of Chemistry, and Institute of Chemical Biology, Vanderbilt University, Nashville, TN 37235.

Umpolung Amide Synthesis (UmAS) has emerged as a superior alternative to conventional amide synthesis methods based on carbonyl electrophiles in a range of situations, particularly when epimerization-prone couplings are prescribed. In an unanticipated development during our most recent studies, it was discovered that diacyl hydrazide products from UmAS were not formed as intermediates when using an acyl hydrazide as the amine acceptor. This resulted in a new preparation of 1,3,4-oxadiazoles from α-bromonitroalkane donors. Read More

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October 2017
3 Reads

Detrifluoroacetylative Generation of Halogenated Enolates: Practical Access to Perhalogenated Ketones and Alkenes.

Synthesis (Stuttg) 2016 Aug 20;48(15):2376-2384. Epub 2016 Apr 20.

Georgetown University, Chemistry Department, Washington, DC, USA.

Sequential chlorination/fluorination of aromatic trifluoroacetylated ketones gives 1-aryl 2-chloro-2,4,4,4-tetrafluoro-butan-1,3-dione hydrates that are used for the synthesis of ketones and alkenes exhibiting a terminal bromochlorofluoromethyl group. The hydrates undergo detrifluoroacetylative cleavage and subsequent bromination in the presence of a copper(II)bisoxazoline catalyst, KCO and NBS at room temperature. The corresponding bromochlorofluoromethyl ketones can be applied in Wittig and Horner-Wadsworth-Emmons reactions and dibromoalkenylations. Read More

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August 2016
8 Reads

N-Heterocyclic Carbene and Chiral Brønsted Acid Cooperative Catalysis for a Highly Enantioselective [4+2] Annulation.

Synthesis (Stuttg) 2017 Jan 18;49(2):293-298. Epub 2016 Nov 18.

Department of Chemistry, Columbia University, New York, New York 10027, United States.

A chiral NHC/Brønsted acid cooperative catalysis system has been developed for asymmetric annulation of functionalized benzaldehydes and activated ketones through dearomative generation of dienolate. Read More

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January 2017
2 Reads

Practical Synthetic Procedures for the Iron-Catalyzed Intermolecular Olefin Aminohydroxylation Using Functionalized Hydroxylamines.

Synthesis (Stuttg) 2016 Sep 25;48(18):3031-3041. Epub 2016 Jul 25.

Department of Chemistry, Georgia State University, 100 Piedmont Avenue SE, Atlanta, GA 30303, USA.

A set of practical synthetic procedures for the iron-catalyzed intermolecular olefin aminohydroxylation reactions in gram scale is reported. In these transformations, a bench-stable functionalized hydroxylamine is applied as the amination reagent. This method is compatible with a broad range of synthetically valuable olefins including those that are incompatible with the existing aminohydroxylation methods. Read More

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September 2016
4 Reads

Asymmetric Synthesis of Dipropionate Derivatives through Catalytic Hydrogenation of Enantioenriched -Ketene Heterodimers.

Synthesis (Stuttg) 2016 Aug 12;48(16):2619-2626. Epub 2016 Apr 12.

Department of Chemistry, Oakland University, 2200 N. Squirrel Road, Rochester, MI 48309-4477, USA.

A highly diastereoselective approach to dipropionate derivatives through Pd/C-catalyzed hydrogenation of enantioenriched -ketene heterodimers is described. Catalytic hydrogenation of the -isomer of ketene heterodimer β-lactones (12 examples) provides access to ,-β-lactones (dipropionate derivatives) bearing up to three stereogenic centers (dr up to 49:1), and with excellent transfer of chirality (ee up to >99%). Read More

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August 2016
7 Reads

Improved Synthesis of MDL 73811 - a Potent AdoMetDC Inhibitor and Anti-Trypanosomal Compound.

Synthesis (Stuttg) 2016 Jul;48(13):2065-2068

Department of Biochemistry, The University of Texas Southwestern Medical Center at Dallas, 5323 Harry Hines Boulevard, Dallas, Texas 75390-9038, United States.

An improved synthesis of MDL 73811 - a potent AdoMetDC (S-adenosylmethionine decarboxylease) inhibitor and anti-trypanosomal compound with in vivo activity has been completed in four steps from commercially available 2',3'--isopropylideneadenosine. Utilization of Mitsunobu chemistry was crucial for the reliable and scalable introduction of the 5'-methylamine moiety, which was problematic using traditional activation/displacement chemistry as previously reported. All reactions in this synthesis were run on gram-scale resulting in a five-fold increase in yield over the original synthesis. Read More

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July 2016
3 Reads

Synthesis of 5-Hydroxymethylcytidine- and 5-Hydroxymethyl-uridine-Modified RNA.

Synthesis (Stuttg) 2016 Apr;48(8):1108-1116

Institute of Organic Chemistry and Center for Molecular Biosciences, CMBI, Leopold-Franzens University, Innrain 80-82, 6020 Innsbruck, Austria.

We report on the syntheses of 5-hydroxymethyl-uridine [5hm(rU)] and -cytidine [5hm(rC)] phosphoramidites and their incorporation into RNA by solid-phase synthesis. Deprotection of the oligonucleotides is accomplished in a straightforward manner using standard conditions, confirming the appropriateness of the acetyl protection used for the pseudobenzylic alcohol moieties. The approach provides robust access to 5hm(rC/U)-modified RNAs that await applications in pull-down experiments to identify potential modification enzymes. Read More

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April 2016
5 Reads

Acetoxy-Substituted Cyclopropane Dicarbonyls as Stable Donor-Acceptor-Acceptor Cyclopropanes.

Synthesis (Stuttg) 2015 Oct;47(19):3020-3026

Department of Chemistry, Mississippi State University, Mississippi State, MS 39762, USA.

A study of cyclopropanations of oxy-substituted ethenes with ethyl α-diazoaroyl acetates is described. Whereas trimethylsilyl vinyl ether and ethyl vinyl ether gave dihydrofuran products, stable cyclopropanes were isolated when vinyl acetate was used. Yields ranged from 0-87%, depending on the nature and position of the aryl ring substituent. Read More

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October 2015
1 Read

Efficient Syntheses of Vitamin K Chain-Shortened Acid Metabolites.

Synthesis (Stuttg) 2015 Apr;47(7):944-948

Department of Medicinal Chemistry, School of Pharmacy, University of Washington, Seattle, WA 98195.

Vitamin K sequentially undergoes ω-oxidation followed by successive rounds of β-oxidation to ultimately produce two chain-shortened carboxylic acid metabolites, vitamin K acid 1 and vitamin K acid 2. Two facile syntheses of these acid metabolites are described, each starting from commercially available menadione-cyclopentadiene adduct . Vitamin K acid 1 was synthesized in five steps alkylation with a geranyl halide followed by subsequent oxidation reactions, while fully retaining the configuration of the side chain 2',3'-double bond. Read More

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April 2015
6 Reads

Iron-Catalyzed Diastereoselective Intramolecular Olefin Aminobromination with Bromide Ion.

Synthesis (Stuttg) 2015 Jun;47(12):1709-1715

Department of Chemistry, Georgia State University, 100 Piedmont Avenue SE, Atlanta, GA 30303, USA.

A new iron-catalyzed diastereoselective aminobromination method is reported for both internal and terminal olefins (yield up to 90% and dr up to >20:1). In this transformation, a functionalized hydroxylamine and bromide ion were used as the nitrogen and bromine source, respectively. This method is compatible with a broad range of olefins and provides a convenient approach to synthetically valuable vicinal bromo primary amines. Read More

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June 2015
1 Read

An Asymmetric Organocatalytic Quadruple Domino Reaction Employing a Vinylogous Friedel-Crafts/Michael/Michael/Aldol Condensation Sequence.

Synthesis (Stuttg) 2015 Apr;47(16):2377-2384

Institute of Organic Chemistry, RWTH Aachen University, Landoltweg 1, 52074 Aachen, Germany.

An organocatalytic quadruple cascade initiated by a Friedel-Crafts-type reaction is described. The ()-diphenylprolinol trimethylsilyl ether catalyzed reaction yields highly functionalized cyclohexenecarbaldehydes bearing a 1,1-bis[4-(dialkylamino)phenyl]ethene moiety and three contiguous stereogenic centers. The reaction tolerates various functional groups and all products are obtained with very good diastereoselectivity and with virtually complete enantiomeric excess. Read More

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April 2015
2 Reads

Organocatalytic Asymmetric Domino Michael/Henry Reaction of Indolin-3-ones with -Formyl-β-nitrostyrenes.

Synthesis (Stuttg) 2015 Apr;47(7):1024-1031

Institute of Organic Chemistry, RWTH Aachen University, Landoltweg 1, 52074 Aachen, Germany.

A highly diastereo- and enantioselective domino Michael/Henry reaction of 1-acetylindolin-3-ones with -formyl-()-β-nitrostyrenes catalyzed by low loading of a quinine-derived amine-squaramide provides the corresponding indolin-3-one derivatives bearing four adjacent stereogenic centers in good to high yields and with excellent stereoselectivities. Read More

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April 2015
3 Reads
2.690 Impact Factor

Organocatalytic Asymmetric Synthesis of Dihydroisoquinolinones via a One-Pot Aza-Henry-Hemiaminalization-Oxidation Sequence.

Synthesis (Stuttg) 2015 Feb;47(4):472-480

Institute of Organic Chemistry, RWTH Aachen University, Landoltweg 1, 52074 Aachen, Germany.

The asymmetric organocatalytic one-pot synthesis of -3,4-disubstituted 3,4-dihydroisoquinolin-1(2)-ones is described. Starting from 2-(nitromethyl)benzaldehydes and various N-protected aldimines, 5 mol% of a quinine-based squaramide organocatalyst was used to synthesize the title compounds as virtually single diastereomers via an aza-Henry-hemiaminalization-oxidation sequence. Moderate to good yields (39-78%) and moderate to very good enantioselectivities (40-95% ee) were reached. Read More

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February 2015
3 Reads

Synthesis of a Series of Novel 3,9-Disubstituted Phenanthrenes as Analogues of Known NMDA Receptor Allosteric Modulators.

Synthesis (Stuttg) 2015 Jun;47(11):1593-1610

School of Physiology & Pharmacology, Medical Sciences Building, University Walk, University of Bristol, Bristol, BS8 1TD, UK.

9-Substituted phenanthrene-3-carboxylic acids have been reported to have allosteric modulatory activity at the NMDA receptor. This receptor is activated by the excitatory neurotransmitter L-glutamate and has been implicated in a range of neurological disorders such as schizophrenia, epilepsy and chronic pain and neurodegenerative disorders such as Alzheimer's disease. Herein, the convenient synthesis of a wide range of novel 3,9-disubstituted phenanthrene derivatives starting from a few common intermediates is described. Read More

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June 2015
9 Reads

Rhodium-Catalyzed Intermolecular [5+1] and [5+2] Cycloadditions Using 1,4-Enynes with an Electron-Donating Ester on the 3-Position.

Synthesis (Stuttg) 2015 May 3;47(8):1076-1084. Epub 2015 Feb 3.

School of Pharmacy, University of Wisconsin, Madison, WI 53706 ; Department of Chemistry, University of Wisconsin, Madison, WI 53705.

Various 3-acyloxy-1,4-enynes could be employed in rhodium-catalyzed intermolecular [5+1] and [5+2] cycloadditions with CO or alkynes, respectively. The rate of these cycloadditions could be accelerated significantly by using 1,4-enynes with an electron-donating ester on the 3-position. The scope of rhodium-catalyzed [5+1] and [5+2] cycloadditions were examined by using 1,4-enynes bearing an electron-donating ester. Read More

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May 2015
2 Reads

(3+2)-Cycloaddition Reactions of Oxyallyl Cations.

Authors:
Hui Li Jimmy Wu

Synthesis (Stuttg) 2015 Jan;47(1):22-33

Department of Chemistry, Dartmouth College, Hanover, NH 03755, USA.

The (3+2)-cycloaddition reaction involving oxyallyl cations has proven to be a versatile and efficient approach for the construction of five-membered carbo- and heterocycles, which are prevalent frameworks in natural products and pharmaceuticals. The following article will provide a brief summary of recent disclosures on this process featuring chemo-, regio- and diastereoselective oxyallyl cycloadditions with both electron-rich and electron-deficient 2π partners. Read More

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January 2015
1 Read

Effect of Substituents and Stability of Transient Aluminum-Aminals in the Presence of Nucleophiles.

Synthesis (Stuttg) 2015 Jan 5;47(2):175-180. Epub 2014 Dec 5.

Department of Chemistry, Purdue University, 560 Oval Drive, West Lafayette, Indiana 47907; Department of BioMolecular Sciences, University of Mississippi, 317 Faser Hall, P. O. Box 1848, University, Mississippi 38677.

Disubstituted hydroxylamines were synthesized and used to form aluminum-amide complexes. These reagents masked carbonyl groups in situ from nucleophilic addition. The stability and utility of the aluminum-aminals are presented in the context of selectively controlling nucleophilic addition on substrates with multiple carbonyl groups. Read More

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January 2015
4 Reads

Asymmetric N-Heterocyclic Carbene Catalyzed Annulation of 2-Alkenylbenzothiazoles with α-Chloro Aldehydes.

Synthesis (Stuttg) 2014 Nov;47(3):421-428

Institute of Organic Chemistry, RWTH Aachen University, Landoltweg 1, 52074 Aachen, Germany.

Diastereo- and enantioselective N-heterocyclic carbene catalyzed 1-azadiene Diels-Alder reactions of ()-2-styrylbenzothiazoles with α-chloro aldehydes are reported. This annulation strategy provides an efficient access to medicinally important dihydrobenzothiazolopyridin-1-ones in good to excellent yields (44-97%) with very good to excellent stereoselectivities (up to 9:1 dr, 98% ee) and tolerates quite a range of substituents. Read More

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November 2014
7 Reads

Nickel-Mediated Synthesis of Isoindolinones at Room Temperature.

Synthesis (Stuttg) 2014 Nov 21;46(22):3033-3040. Epub 2014 Aug 21.

St. Olaf College, Department of Chemistry, 1520 St. Olaf Ave., Northfield, MN 55057, USA.

This communication describes a method for the Ni(cod) -mediated intramolecular arylation of alkyl C-H bonds adjacent to the nitrogen atom in benzamide substrates. The transformation proceeds at room temperature and exhibits selectivity for functionalization of more substituted C-H bonds. The yields of the desired isoindolinone products are higher with benzamide substrates containing tertiary alkyl groups on the nitrogen atom than with those bearing primary or secondary alkyls. Read More

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November 2014
6 Reads

Copper-Catalyzed Decarboxylative Trifluoromethylation of Propargyl Bromodifluoroacetates.

Synthesis (Stuttg) 2014 Jul;46(14):1938-1946

Department of Medicinal Chemistry, The University of Kansas, 1251 Wescoe Hall Drive, Lawrence, Kansas 66045, United States.

The development of efficient methods for accessing fluorinated functional groups is desirable. Herein, we report a two-step method that utilizes catalytic Cu for the decarboxylative trifluoromethylation of propargyl bromodifluoroacetates. This protocol affords a mixture of propargyl trifluoromethanes and trifluoromethyl allenes. Read More

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July 2014
6 Reads

Asymmetric Synthesis of Functionalized Dihydro- and Tetrahydropyrans via an Organocatalytic Domino Michael-Hemiacetalization Reaction.

Synthesis (Stuttg) 2014 May;46(9):1261-1269

Institute of Organic Chemistry, RWTH Aachen University, Landoltweg 1, 52074 Aachen, Germany.

Starting from α-hydroxymethyl nitroalkenes and various 1,3-dicarbonyl compounds, a one-pot organocatalyzed diastereo- and enantioselective synthesis of polyfunctionalized dihydro- and tetrahydropyran derivatives via a domino Michael-hemiacetalization sequence is reported. The title compounds bearing a variety of functional groups can be synthesized in this way in good yields (59-91%) and with moderate to excellent diastereoselectivities (26-98% de) and enantioselectivities (71-99% ee). Read More

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May 2014
26 Reads

Organocatalytic Asymmetric Synthesis of Functionalized 1,3,5-Triarylpyrrolidin-2-ones via an Aza-Michael/Aldol Domino Reaction.

Synthesis (Stuttg) 2014 Mar;46(6):799-808

Institute of Organic Chemistry, RWTH Aachen University, Landoltweg 1, 52074 Aachen, Germany.

The organocatalytic asymmetric synthesis of functionalized 1,3,5-triarylpyrrolidin-2-ones bearing three contiguous stereocenters through an aza-Michael/aldol domino reaction of α-ketoamides with α,β-unsaturated aldehydes is described. The domino products were further derivatized by aldehyde olefination under one-pot conditions. The reaction proceeds with excellent diastereoselectivities (>20:1) and good to excellent enantioselectivities (60-96% ee). Read More

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March 2014
1 Read

An Asymmetric Organocatalytic Quadruple Cascade to Tetraaryl-Substituted 2-Azabicyclo[3.3.0]octadienones.

Synthesis (Stuttg) 2014 Jun;46(11):1539-1546

Institute of Organic Chemistry, RWTH Aachen University, Landoltweg 1, 52074 Aachen, Germany.

A new asymmetric organocatalytic three-component quadruple cascade of α-ketoamides with α,β-unsaturated aldehydes is described. The reaction is catalyzed by the ()-diphenylprolinol TMS ether catalyst and proceeds via an aza-Michael/aldol condensation/vinylogous Michael/aldol condensation sequence to yield tetraaryl-substituted 2-azabicyclo[3.3. Read More

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June 2014
6 Reads

Substituted 2,2'-bipyridines by nickel-catalysis: 4,4'-di--butyl-2,2'-bipyridine.

Synthesis (Stuttg) 2013 Nov;45(22):3099-3102

Department of Chemistry, University of Rochester, Rochester, NY 14627-0216 USA.

A simple, ligand-free synthesis of the important bipyridyl ligand 4,4'-di--butyl-2,2'-bipyridine is presented. 5,5'-bis(trifluoromethyl)-2,2'-bipyridine is also synthesized by the same protocol. The syntheses efficiently couple the parent 2-chlorpyridies by a nickel-catalyzed dimerization with manganese powder as the terminal reductant. Read More

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November 2013
8 Reads

Syntheses of 3-[(Alkylamino)methylene]-6-methylpyridine-2,4(1,3)-diones, 3-Substituted 7-Methyl-2-pyrano[3,2-]pyridine-2,5(6)-dione Fluorescence Probes, and Tetrahydro-1,9-2,10-dioxa-9-azaanthracen-1-ones.

Synthesis (Stuttg) 2014 Aug;46(16):2179-2190

Department of Chemistry, College of Arts and Sciences, Kansas State University, Manhattan, KS 66506-0401, USA.

Various condensation and ring-closing reactions were used for the syntheses of 3-[(alkylamino)methylene]-6-methylpyri-dine-2,4(1,3)-diones, bicyclic pyridinones, and tricyclic morpholinopyrones. For instance, 3-[(dialkylamino)methylene]-6-methylpyridine-2,4(1,3)-diones were synthesized from the condensation of dialkylamines and 3-formyl-4-hydroxy-6-methylpyridin-2(1)-one. 3-Formyl-4-hydroxy-6-methylpyridin-2(1)-one, derived from 3-formyl-4-hydroxy-6-methylpyridin-2(1)-one, was used to construct a number of bicyclic pyridinones via a one-pot Knoevenagal and intramolecular lactonization reaction. Read More

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August 2014
12 Reads
2.690 Impact Factor

Reductive Cyclizations of Nitroarenes to Hydroxamic Acids by Visible Light Photoredox Catalysis.

Synthesis (Stuttg) 2013 Oct;45(19):2699-2705

Department of Chemistry, University of Wisconsin-Madison, 1101 University Avenue, Madison, WI 53706, USA.

We have developed a photocatalytic reduction of nitroarenes as an efficient, chemoselective route to biologically important -phenyl hydroxamic acid scaffolds. Optimal conditions call for 2.5 mol% of a ruthenium photocatalyst, visible light irradiation, and a dihydropyridine terminal reductant. Read More

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October 2013
7 Reads

Efficient and Scalable Synthesis of 4-Carboxy-Pennsylvania Green Methyl Ester: A Hydrophobic Building Block for Fluorescent Molecular Probes.

Synthesis (Stuttg) 2014 Jan;46(2):158-164

Department of Medicinal Chemistry, The University of Kansas, Lawrence, KS 66045, United States.

Fluorinated fluorophores are valuable tools for studies of biological systems. However, amine-reactive single-isomer derivatives of these compounds are often very expensive. To provide an inexpensive alternative, we report a practical synthesis of 4-carboxy-Pennsylvania Green methyl ester. Read More

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January 2014
4 Reads

A Bis(phosphine)-Modified Peptide Ligand for Stable and Luminescent Quantum Dots in Aqueous Media.

Synthesis (Stuttg) 2013 Sep;45(17):2426-2430

Department of Chemistry and Biochemistry, California NanoSystems Institute, and Department of Physiology, University of California at Los Angeles, Los Angeles, CA 90095-1569, USA.

We describe a new class of ligands for semiconductor nanoparticles (quantum dots = QDs), which bind well and allow for their facile dissolution in aqueous solution. As a proof of principle, we have designed and synthesized a novel bis(phosphine)-modified peptide (BPMP) and shown that it has the ability to solubilize quantum dots in aqueous media. We further showed that the corresponding phosphine oxide derivatives of these new ligands are less good at solubilizing the quantum dots. Read More

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September 2013
3 Reads

Synthesis of Cyclic α-Aminophosphonates through Copper Catalyzed Enamine Activation.

Synthesis (Stuttg) 2013 Feb;45(4):463-470

Department of Chemistry, University of Louisville, Louisville, KY 40292, USA.

A copper-catalyzed tandem cyclization triggered addition strategy that relies on electrophilic enamine activation has been used to synthesize various cyclic α-aminophosphonates derivatives in good to excellent yields. Both five and six membered rings can be generated under mild conditions with high regioselectivity. A mechanism based on copper catalyzed enamine activation is proposed. Read More

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February 2013
2 Reads

An Efficient Synthesis of 4(5)-Benzyl-L-Histidines Employing Catalytic Transfer Hydrogenolysis at Elevated Temperatures.

Synthesis (Stuttg) 2014 Feb 10;46(4):515-521. Epub 2013 Dec 10.

Department of Chemistry, Creighton University, 2500 California Plaza, Omaha, NE 68178, U.S.A.

An efficient two-step synthesis of 4(5)-benzyl-L-histidine from L-histidine was developed. A Pictet-Spengler reaction between L-histidine and benzaldehyde in the presence of excess strong base yielded 4-phenylspinacine within one hour. Catalytic transfer hydrogenolysis in methanol at reflux using ammonium formate rapidly converted 4-L-phenylspinacine to 4(5)-benzyl-L-histidine within five minutes. Read More

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February 2014
5 Reads

Facile Access to Ring-Fused Aminals via Direct α-Amination of Secondary Amines with -Aminobenzaldehydes. Synthesis of Vasicine, Deoxyvasicine, Deoxyvasicinone, Mackinazolinone and Ruteacarpine.

Synthesis (Stuttg) 2013 Oct;45(13):1430-1748

Department of Chemistry and Chemical Biology, Rutgers, The State University of New Jersey, Piscataway, New Jersey 08854, USA.

Secondary amines undergo redox-neutral reactions with aminobenzaldehydes under conventional and microwave heating to furnish polycyclic aminals via amine α-amination/-alkylation. This unique α-functionalization reaction proceeds without the involvement of transition metals or other additives. The resulting aminal products are precursors for various quinazolinone alkaloids and their analogues. Read More

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October 2013
33 Reads

A Convenient Synthesis of γ-Amino-Ynamides via Additions of Lithiated Ynamides to Aryl Imines. Observation of an -Meyer-Schuster Rearrangement.

Synthesis (Stuttg) 2013 Jul;45(13):1749-1758

School of Pharmaceutical Science and Technology, and Tianjin Key Laboratory for Modern Drug Delivery & High-Efficiency, Tianjin University, Tianjin 300072 P. R. China.

Efforts in developing an expeditious and convenient method for synthesizing γ-amino-ynamides via nucleophilic addition of lithiated ynamides to aryl imines are described. This work also features an -variant of a Meyer-Schuster rearrangement of γ-amino-ynamides and the synthetic utility of γ-amino-ynamides in an intramolecular ketenimine-[2 + 2] cycloaddition. Read More

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July 2013
10 Reads

Enantioselective Synthesis of the Tricyclic Core of FR901483 Featuring a Rh-Catalyzed [2+2+2] Cycloaddition.

Synthesis (Stuttg) 2013 ;45(6):719-728

Department of Chemistry, Colorado State University, Fort Collins, CO 80523.

An efficient approach to the tricyclic framework of FR901483 is described. The sequence features a [3, 3]-sigmatropic rearrangement of a cyanate into an isocyanate, followed by its subsequent asymmetric rhodium-catalyzed [2+2+2] cycloaddition with a terminal alkyne for the synthesis of the indolizidine core. The -tricyclic core is completed using an intramolecular benzoin reaction to close the last ring of the natural product. Read More

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January 2013
3 Reads

Lead Diversification through a Prins-Driven Macrocyclization Strategy: Application to C13-Diversified Bryostatin Analogues.

Synthesis (Stuttg) 2013 ;45(13):1815-1824

Department of Radiology, Stanford University School of Medicine, Stanford, CA 94305-5105, USA.

The design, synthesis, and biological evaluation of a novel class of C13-diversified bryostatin analogues are described. An innovative and general strategy based on a Prins macrocyclization-nucleophilic trapping cascade was used to achieve late-stage diversification. In vitro analysis of selected library members revealed that modification at the C13 position of the bryostatin scaffold can be used as a diversification handle to regulate biological activity. Read More

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January 2013
1 Read

Recent Developments in Pd-Catalyzed Alkene Aminoarylation Reactions for the Synthesis of Nitrogen Heterocycles.

Synthesis (Stuttg) 2012 ;44(3):351-361

Department of Chemistry, University of Michigan, 930 N. University Avenue, Ann Arbor, MI 48109-1055, USA.

This short review describes new developments in Pd-catalyzed aminoarylation reactions between aryl halides and alkenes bearing pendant nitrogen nucleophiles. These transformations provide a novel and powerful method for accessing numerous 3-, 5-, 6-, and 7-membered nitrogen heterocycles. Read More

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January 2012
24 Reads

Diastereoselective Synthesis of Substituted Tetrahydropyrans by Copper(II)-Bisphosphine-Catalyzed Olefin Migration and Prins Cyclization.

Synthesis (Stuttg) 2012 Dec;44(23):3579-3589

Department of Chemistry and Department of Medicinal Chemistry, Purdue University, West Lafayette, IN 47907, USA, Fax +1(765)4961612.

We developed a copper(II) triflate-bisphosphine complex catalyzed olefin migration and Prins cyclization which lead to the synthesis of substituted tetrahydropyran derivatives. The protocol is convenient and a variety of substituted tetrahydropyrans were obtained in good to excellent yields with excellent diastereoselectivities. Read More

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December 2012

Investigations Concerning the Syntheses of TADDOL-Derived Secondary Amines and Their Use To Access Novel Chiral Organocatalysts.

Synthesis (Stuttg) 2012 Dec;44(23):3661-3670

Institute of Organic Chemistry, Johannes Kepler University Linz, Altenbergerstraße 69, 4040 Linz, Austria.

A structurally carefully diversified library of novel TADDOL-derived chiral secondary amines was synthesized and investigated for their applicability to obtain new organocatalysts like chiral Lewis bases and chiral phase-transfer catalysts. The scope and limitations of the developed syntheses routes to access these catalysts as well their catalytic performance in different benchmark reactions were systematically investigated. The most powerful of the catalysts prepared was found to be highly useful for the phase-transfer catalyzed α-alkylation of glycine Schiff base (high yields and up to 93% ee). Read More

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December 2012
1 Read

Functionalized Cyclopropenes and Methylenecyclopropenes from Dianions of 3-Hydroxymethylcyclopropenes.

Synthesis (Stuttg) 2012 ;44(18):2843-2850

Brown Laboratories, Department of Chemistry and Biochemistry, University of Delaware, Newark DE 19716, USA.

1,2-Disubstituted-3-hydroxymethylcyclopropene derivatives have been synthesized by reacting the dianions of 1-alkyl-3-hydroxymethylcyclopropenes with a range of electrophiles. Additionally, a complementary procedure is described for one-pot sequential alkylation/rearrangement to provide a convenient synthesis of a chiral methylenecyclopropane directly from a 1-alkyl-3-hydroxymethylcyclopropene. Read More

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January 2012
3 Reads

Second-Generation Synthesis of (-)-Viriditoxin.

Synthesis (Stuttg) 2012 ;2012(3):362-371

Department of Chemistry, University of California, One Shields Ave, Davis, CA 95616.

Viriditoxin is a secondary metabolite isolated from Aspergillus viridinutans that has been shown to inhibit FtsZ, the bacterial homologue of eukaryotic tubulin. A streamlined, scalable, and highly diastereoselective synthesis of this complex natural product is described. Key advances include a more efficient synthesis of the requisite unsaturated pyranone, scalable assembly of the naphthopyranone monomer, and improved diastereoselectivity in the biaryl-coupling reaction. Read More

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January 2012
2 Reads

Heterocycle Formation Palladium-Catalyzed C-H Functionalization.

Synthesis (Stuttg) 2012 Jun 25;44(12):1778-1791. Epub 2012 May 25.

Department of Chemistry, The Scripps Research Institute, 10550 North Torrey Pines Rd., La Jolla, CA 92037 (USA).

Heterocyclic compounds are ubiquitous in natural products, pharmaceuticals, and agrochemicals. Therefore, the design of novel protocols to construct heterocycles more efficiently is a major area of focus in the organic chemistry. In the past several years, cyclization reactions based upon palladium-catalyzed C-H activation have received substantial attention due to their capacity for expediting heterocycle synthesis. Read More

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June 2012
10 Reads

Multigram Synthesis of a Chiral Substituted Indoline Via Copper-Catalyzed Alkene Aminooxygenation.

Synthesis (Stuttg) 2012 May 22;44(10):1481-1484. Epub 2012 Apr 22.

Department of Chemistry, The State University of New York at Buffalo, Buffalo, New York, 14260, USA.

(S)-5-Fluoro-2-(2,2,6,6-tetramethylpiperidin-1-yloxymethyl)-1-tosylindoline, a 2-methyleneoxy-substituted chiral indoline, was synthesized on multigram scale using an efficient copper-catalyzed enantioselective intramolecular alkene aminooxygenation. The synthesis is accomplished in four steps and the indoline is obtained in 89% ee (>98% after one recrystallization). Other highlights include efficient gram-scale synthesis of the (4R,5S)-di-Ph-box ligand and efficient separation of a monoallylaniline from its bis(allyl)aniline by-product by distillation under reduced pressure. Read More

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May 2012
1 Read

Automated Multistep Continuous Flow Synthesis of 2-(-Indol-3-yl)thiazole Derivatives.

Synthesis (Stuttg) 2012 ;44(16):2537-2546

Apoptosis and Cell Death Research Program & Conrad Prebys Center for Chemical Genomics, Sanford-Burnham Medical Research Institute, 10901 N. Torrey Pines Rd., La Jolla, CA 92037.

The multistep continuous flow assembly of 2-(-indol-3-yl)thiazoles using a Syrris AFRICA synthesis station is reported. Sequential Hantzsch thiazole synthesis, deketalization and Fischer indole synthesis provides rapid and efficient access to highly functionalized, pharmacologically significant 2-(-indol-3-yl)thiazoles. These complex, drug-like small molecules are generated in reaction times of less than 15 min and in high yields (38%-82% over three chemical steps without isolation of intermediates). Read More

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January 2012
3 Reads

Synthetic Routes to a Series of Proximal and Distal 2'-Deoxy Fleximers.

Synthesis (Stuttg) 2012 ;44(22):3496-3504

Department of Chemistry and Biochemistry, University of Maryland Baltimore County, 1000 Hilltop Circle, Baltimore, MD, 21250, USA Fax +1(410)4552608.

Two series of innovative 2'-deoxy nucleoside analogues have been designed where the nucleobase has been split into its imidazole and pyrimidine subunits. This structural modification serves to introduce flexibility into the nucleobase scaffold while still retaining the elements required for recognition. The synthetic efforts to realize these analogues are described within. Read More

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January 2012
4 Reads