Publications by authors named "Artis Kinens"

7 Publications

  • Page 1 of 1

Metal-free glycosylation with glycosyl fluorides in liquid SO.

Beilstein J Org Chem 2021 29;17:964-976. Epub 2021 Apr 29.

Institute of Technology of Organic Chemistry, Faculty of Materials Science and Applied Chemistry, Riga Technical University, P. Valdena str. 3, Riga, LV-1048, Latvia.

Liquid SO is a polar solvent that dissolves both covalent and ionic compounds. Sulfur dioxide possesses also Lewis acid properties, including the ability to covalently bind Lewis basic fluoride ions in a relatively stable fluorosulfite anion (FSO). Herein we report the application of liquid SO as a promoting solvent for glycosylation with glycosyl fluorides without any external additive. By using various temperature regimes, the method is applied for both armed and disarmed glucose and mannose-derived glycosyl fluorides in moderate to excellent yields. A series of pivaloyl-protected - and -mannosides, as well as one example of a -mannoside, are synthesized to demonstrate the scope of the glycosyl acceptors. The formation of the fluorosulfite species during the glycosylation with glycosyl fluorides in liquid SO is proved by F NMR spectroscopy. A sulfur dioxide-assisted glycosylation mechanism that proceeds via solvent separated ion pairs is proposed, whereas the observed α,β-selectivity is substrate-controlled and depends on the thermodynamic equilibrium.
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http://dx.doi.org/10.3762/bjoc.17.78DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8093551PMC
April 2021

Acylative Dynamic Kinetic Resolution of Secondary Alcohols: Tandem Catalysis by HyperBTM and Bäckvall's Ruthenium Complex.

J Org Chem 2021 May 11;86(10):7189-7202. Epub 2021 May 11.

Latvian Institute of Organic Synthesis, Aizkraukles 21, Riga LV-1006, Latvia.

Non-enzymatic dynamic kinetic resolution (DKR) of secondary alcohols by enantioselective acylation using an isothiourea-derived HyperBTM catalyst and racemization of slowly reacting alcohol by Bäckvall's ruthenium complex is reported. The DKR approach features high enantioselectivities (up to 99:1), employs easy-to-handle crystalline 4-nitrophenyl isobutyrate as the acylating reagent, and proceeds at room temperature and under an ambient atmosphere. The stereoinduction model featuring cation-π system interactions between the acylated HyperBTM catalyst and π electrons of an alcohol aryl subunit has been elaborated by DFT calculations.
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http://dx.doi.org/10.1021/acs.joc.1c00545DOI Listing
May 2021

-Fluorine Effect in Cyclopropane: Diastereoselective Synthesis of Fluorocyclopropyl Cabozantinib Analogs.

ACS Med Chem Lett 2020 Nov 11;11(11):2146-2150. Epub 2020 Sep 11.

Latvian Institute of Organic Synthesis, Aizkraukles 21, Riga LV-1006, Latvia.

Investigation of the -fluorine effect on the hydrolysis rate of diethyl 2-fluorocyclopropane-1,1-dicarboxylate provides synthetic access to both diastereomers of the fluorocyclopropyl analog of cabozantinib, a c-Met and VEGFR-2 inhibitor used as a first-line treatment for thyroid cancer and as a second-line treatment for renal cell carcinoma. Despite some known potent examples, there are only a few drug molecules that contain fluorocyclopropane moieties. Herein, we present a case study in which the monofluoro analog of a known cyclopropane-containing drug molecule displays an improved profile compared to the parent nonfluorinated structure. The fluorocyclopropane moiety may offer valuable fine-tuning options for lead optimization in drug discovery.
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http://dx.doi.org/10.1021/acsmedchemlett.0c00220DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7667865PMC
November 2020

Cation-π interactions secure aggregation induced emission of planar organic luminophores.

Chem Commun (Camb) 2019 Oct;55(84):12663-12666

Latvian Institute of Organic Synthesis, Aizkraukles 21, Riga, LV-1006, Latvia.

The use of non-covalent intermolecular π+-π interactions between quaternary pyridinium or imidazolium cations and aromatic π systems is an efficient approach to achieve AIE in planar purely organic luminophores.
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http://dx.doi.org/10.1039/c9cc06829eDOI Listing
October 2019

Preparative-Scale Synthesis of Vedejs Chiral DMAP Catalysts.

J Org Chem 2018 Oct 10;83(20):12449-12459. Epub 2018 Oct 10.

Latvian Institute of Organic Synthesis , Aizkraukles 21 , LV-1006 Riga , Latvia.

A scalable synthesis of chiral Vedejs-type DMAP catalysts is reported. The key step of the synthesis is amination of the enantiomerically pure 4-chloropyridine derivative using well-defined ZnCl(amine) complexes. A series of Zn(II)-amine complexes have been synthesized to explore the scope of the ZnCl-mediated amination of 4-halopyridines. Mechanistic studies support a Zn(II)-facilitated nucleophilic aromatic substitution as a plausible mechanism for the chlorine-to-amine exchange.
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http://dx.doi.org/10.1021/acs.joc.8b01687DOI Listing
October 2018

Development of a Chiral DMAP Catalyst for the Dynamic Kinetic Resolution of Azole Hemiaminals.

J Org Chem 2017 01 11;82(2):869-886. Epub 2017 Jan 11.

Latvian Institute of Organic Synthesis , Aizkraukles 21, LV-1006 Riga, Latvia.

A new catalyst for the dynamic kinetic resolution of azole hemiaminals has been developed using late-stage structural modifications of the tert-leucinol-derived chiral subunit of DMAP species.
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http://dx.doi.org/10.1021/acs.joc.6b02955DOI Listing
January 2017

Unsaturated syn- and anti-1,2-amino alcohols by cyclization of allylic bis-trichloroacetimidates. stereoselectivity dependence on substrate configuration.

J Org Chem 2015 Jan 22;80(2):920-7. Epub 2014 Dec 22.

Latvian Institute of Organic Synthesis , Aizkraukles 21, Riga LV-1006, Latvia.

Disubstituted allylic bis-imidates undergo Lewis acid catalyzed or spontaneous cyclization to oxazolines, which are precursors of unsaturated amino alcohols. Stereoselectivity of the cyclization is mainly determined by the substrate configuration. Highly selective cis-oxazoline formation is achieved starting from anti-E-bis-imidates while trans-oxazoline predominantly forms from anti-Z-bis-imidates. On the basis of DFT calculations, the stereoselectivity trends can be explained by the formation of the energetically most stable carbenium ion conformation, followed by the cyclization via most favorable bond rotations.
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http://dx.doi.org/10.1021/jo502404yDOI Listing
January 2015