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Article ; Online: Reactions of Allylmagnesium Reagents with Carbonyl Compounds and Compounds with C═N Double Bonds: Their Diastereoselectivities Generally Cannot Be Analyzed Using the Felkin-Anh and Chelation-Control Models.

Bartolo, Nicole D / Read, Jacquelyne A / Valentín, Elizabeth M / Woerpel, K A

2020 Volume 120, Issue 3, Page(s) 1513–1619

Abstract: This review describes the additions of allylmagnesium reagents to carbonyl compounds and to imines, focusing on the differences in reactivity between allylmagnesium halides and other Grignard reagents. In many cases, allylmagnesium reagents either react ... ...

Abstract	This review describes the additions of allylmagnesium reagents to carbonyl compounds and to imines, focusing on the differences in reactivity between allylmagnesium halides and other Grignard reagents. In many cases, allylmagnesium reagents either react with low stereoselectivity when other Grignard reagents react with high selectivity, or allylmagnesium reagents react with the opposite stereoselectivity. This review collects hundreds of examples, discusses the origins of stereoselectivities or the lack of stereoselectivity, and evaluates why selectivity may not occur and when it will likely occur.
MeSH term(s)	Alcohols/chemical synthesis ; Aldehydes/chemistry ; Allyl Compounds/chemistry ; Ketones/chemistry ; Magnesium/chemistry ; Organometallic Compounds/chemistry ; Stereoisomerism
Chemical Substances	Alcohols ; Aldehydes ; Allyl Compounds ; Ketones ; Organometallic Compounds ; Magnesium (I38ZP9992A)
Language	English
Publishing date	2020-01-06
Publishing country	United States
Document type	Journal Article ; Research Support, N.I.H., Extramural ; Research Support, Non-U.S. Gov't ; Review
ZDB-ID	207949-5
ISSN	1520-6890 ; 0009-2665
ISSN (online)	1520-6890
ISSN	0009-2665
DOI	10.1021/acs.chemrev.9b00414
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Article: Reactions of Allylmagnesium Reagents with Carbonyl Compounds and Compounds with C═N Double Bonds: Their Diastereoselectivities Generally Cannot Be Analyzed Using the Felkin–Anh and Chelation-Control Models

Bartolo, Nicole D / Read, Jacquelyne A / Valentín, Elizabeth M / Woerpel, K. A

Chemical reviews. 2020 Jan. 06, v. 120, no. 3

2020

Abstract	This review describes the additions of allylmagnesium reagents to carbonyl compounds and to imines, focusing on the differences in reactivity between allylmagnesium halides and other Grignard reagents. In many cases, allylmagnesium reagents either react with low stereoselectivity when other Grignard reagents react with high selectivity, or allylmagnesium reagents react with the opposite stereoselectivity. This review collects hundreds of examples, discusses the origins of stereoselectivities or the lack of stereoselectivity, and evaluates why selectivity may not occur and when it will likely occur.
Keywords	Grignard reagents ; carbonyl compounds ; chemical bonding ; diastereoselectivity ; halides ; imines ; models
Language	English
Dates of publication	2020-0106
Size	p. 1513-1619.
Publishing place	American Chemical Society
Document type	Article
ZDB-ID	207949-5
ISSN	1520-6890 ; 0009-2665
ISSN (online)	1520-6890
ISSN	0009-2665
DOI	10.1021/acs.chemrev.9b00414
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Article: Diastereoselective Additions of Allylmagnesium Reagents to α-Substituted Ketones When Stereochemical Models Cannot Be Used

Bartolo, Nicole D. / Demkiw, Krystyna M. / Valentín, Elizabeth M. / Hu, Chunhua T. / Arabi, Alya A. / Woerpel, K. A.

Journal of organic chemistry. 2021 May 12, v. 86, no. 10

2021

Abstract: The stereoselectivities of reactions of allylmagnesium reagents with chiral ketones cannot be easily explained by stereochemical models. Competition experiments indicate that the complexation step is not reversible, so nucleophiles cannot access the ... ...

Abstract	The stereoselectivities of reactions of allylmagnesium reagents with chiral ketones cannot be easily explained by stereochemical models. Competition experiments indicate that the complexation step is not reversible, so nucleophiles cannot access the widest range of possible encounter complexes and therefore cannot be analyzed easily using available models. Nevertheless, additions of allylmagnesium reagents to a ketone can still be stereoselective provided that the carbonyl group adopts a conformation that leads to one face being completely blocked from the approach of the allylmagnesium reagent.
Keywords	Lewis bases ; diastereoselectivity ; face ; organic chemistry ; stereochemistry
Language	English
Dates of publication	2021-0512
Size	p. 7203-7217.
Publishing place	American Chemical Society
Document type	Article
ZDB-ID	123490-0
ISSN	1520-6904 ; 0022-3263
ISSN (online)	1520-6904
ISSN	0022-3263
DOI	10.1021/acs.joc.1c00553
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Article: Conformationally Biased Ketones React Diastereoselectively with Allylmagnesium Halides

Bartolo, Nicole D. / Demkiw, Krystyna M. / Read, Jacquelyne A. / Valentín, Elizabeth M. / Yang, Yingying / Dillon, Alexandra M. / Hu, Chunhua T. / Ward, Michael D. / Woerpel, K. A.

Journal of organic chemistry. 2022 Feb. 15, v. 87, no. 5

2022

Abstract: The addition of the highly reactive reagent allylmagnesium halide to α-substituted acyclic chiral ketones proceeded with high stereoselectivity. The stereoselectivity cannot be analyzed by conventional stereochemical models because these reactions do not ...

Abstract	The addition of the highly reactive reagent allylmagnesium halide to α-substituted acyclic chiral ketones proceeded with high stereoselectivity. The stereoselectivity cannot be analyzed by conventional stereochemical models because these reactions do not conform to the requirements of those models. Instead, the stereoselectivity arises from the approach of the nucleophile to the most accessible diastereofaces of the lowest-energy conformations of the ketones. High stereoselectivity is expected, and the stereochemical outcome can be predicted, with conformationally biased ketones that have sterically distinguishable diastereofaces wherein only one face is accessible for nucleophilic addition. The conformations of the ketones can be determined by a combination of computational modeling and, in some cases, structure determination by X-ray crystallography.
Keywords	Lewis bases ; X-ray diffraction ; diastereoselectivity ; face ; organic chemistry ; stereochemistry
Language	English
Dates of publication	2022-0215
Size	p. 3042-3065.
Publishing place	American Chemical Society
Document type	Article
ZDB-ID	123490-0
ISSN	1520-6904 ; 0022-3263
ISSN (online)	1520-6904
ISSN	0022-3263
DOI	10.1021/acs.joc.1c02844
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Article ; Online: Diastereoselective Additions of Allylmagnesium Reagents to α-Substituted Ketones When Stereochemical Models Cannot Be Used.

Bartolo, Nicole D / Demkiw, Krystyna M / Valentín, Elizabeth M / Hu, Chunhua T / Arabi, Alya A / Woerpel, K A

The Journal of organic chemistry

2021 Volume 86, Issue 10, Page(s) 7203–7217

Abstract	The stereoselectivities of reactions of allylmagnesium reagents with chiral ketones cannot be easily explained by stereochemical models. Competition experiments indicate that the complexation step is not reversible, so nucleophiles cannot access the widest range of possible encounter complexes and therefore cannot be analyzed easily using available models. Nevertheless, additions of allylmagnesium reagents to a ketone can still be stereoselective provided that the carbonyl group adopts a conformation that leads to one face being completely blocked from the approach of the allylmagnesium reagent.
MeSH term(s)	Indicators and Reagents ; Ketones ; Stereoisomerism
Chemical Substances	Indicators and Reagents ; Ketones
Language	English
Publishing date	2021-05-12
Publishing country	United States
Document type	Journal Article ; Research Support, N.I.H., Extramural ; Research Support, U.S. Gov't, Non-P.H.S.
ZDB-ID	123490-0
ISSN	1520-6904 ; 0022-3263
ISSN (online)	1520-6904
ISSN	0022-3263
DOI	10.1021/acs.joc.1c00553
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Article ; Online: Conformationally Biased Ketones React Diastereoselectively with Allylmagnesium Halides.

Bartolo, Nicole D / Demkiw, Krystyna M / Read, Jacquelyne A / Valentín, Elizabeth M / Yang, Yingying / Dillon, Alexandra M / Hu, Chunhua T / Ward, Michael D / Woerpel, K A

The Journal of organic chemistry

2022 Volume 87, Issue 5, Page(s) 3042–3065

Abstract	The addition of the highly reactive reagent allylmagnesium halide to α-substituted acyclic chiral ketones proceeded with high stereoselectivity. The stereoselectivity cannot be analyzed by conventional stereochemical models because these reactions do not conform to the requirements of those models. Instead, the stereoselectivity arises from the approach of the nucleophile to the most accessible diastereofaces of the lowest-energy conformations of the ketones. High stereoselectivity is expected, and the stereochemical outcome can be predicted, with conformationally biased ketones that have sterically distinguishable diastereofaces wherein only one face is accessible for nucleophilic addition. The conformations of the ketones can be determined by a combination of computational modeling and, in some cases, structure determination by X-ray crystallography.
MeSH term(s)	Indicators and Reagents ; Ketones/chemistry ; Molecular Conformation ; Stereoisomerism
Chemical Substances	Indicators and Reagents ; Ketones
Language	English
Publishing date	2022-02-15
Publishing country	United States
Document type	Journal Article ; Research Support, N.I.H., Extramural ; Research Support, U.S. Gov't, Non-P.H.S.
ZDB-ID	123490-0
ISSN	1520-6904 ; 0022-3263
ISSN (online)	1520-6904
ISSN	0022-3263
DOI	10.1021/acs.joc.1c02844
Database	MEDical Literature Analysis and Retrieval System OnLINE

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Article ; Online: Heritable nanosilver resistance in priority pathogen: a unique genetic adaptation and comparison with ionic silver and antibiotics.

Valentin, Elizabeth / Bottomley, Amy L / Chilambi, Gayatri S / Harry, Elizabeth J / Amal, Rose / Sotiriou, Georgios A / Rice, Scott A / Gunawan, Cindy

Nanoscale

2020 Volume 12, Issue 4, Page(s) 2384–2392

Abstract: The past decade has seen the incorporation of antimicrobial nanosilver (NAg) into medical devices, and, increasingly, in everyday 'antibacterial' products. With the continued rise of antibiotic resistant bacteria, there are concerns that these priority ... ...

Abstract	The past decade has seen the incorporation of antimicrobial nanosilver (NAg) into medical devices, and, increasingly, in everyday 'antibacterial' products. With the continued rise of antibiotic resistant bacteria, there are concerns that these priority pathogens will also develop resistance to the extensively commercialized nanoparticle antimicrobials. Herein, this work reports the emergence of stable resistance traits to NAg in the WHO-listed priority pathogen Staphylococcus aureus, which has previously been suggested to have no, or very low, capacity for silver resistance. With no native presence of genetically encoded silver defence mechanisms, the work showed that the bacterium is dependent on mutation of physiologically essential genes, including those involved in nucleotide synthesis and oxidative stress defence. While some mutations were uniquely associated with resistance to NAg, the study also found common mutations that could be protective against both NAg and ionic silver. This is consistent with the observation of NAg/ionic silver cross-resistance. These mutations were detected following withdrawal of the silver exposure, denoting heritable characteristics that allow for spread of the resistance traits even with discontinued silver use. Heritable silver resistance in priority pathogen cautions that these nanoparticle antimicrobials should only be used as needed, to preserve their efficacy for treating infections.
MeSH term(s)	Anti-Bacterial Agents/pharmacology ; Ciprofloxacin/pharmacology ; Drug Resistance, Bacterial ; Gene Deletion ; Ions ; Metal Nanoparticles/chemistry ; Microbial Sensitivity Tests ; Mutation ; Oxidative Stress ; Point Mutation ; Silver/pharmacology ; Staphylococcus aureus/drug effects ; Staphylococcus aureus/genetics
Chemical Substances	Anti-Bacterial Agents ; Ions ; colloidal silver ; Silver (3M4G523W1G) ; Ciprofloxacin (5E8K9I0O4U)
Language	English
Publishing date	2020-01-13
Publishing country	England
Document type	Journal Article
ZDB-ID	2515664-0
ISSN	2040-3372 ; 2040-3364
ISSN (online)	2040-3372
ISSN	2040-3364
DOI	10.1039/c9nr08424j
Database	MEDical Literature Analysis and Retrieval System OnLINE

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Article ; Online: Solvent effects in the nucleophilic substitutions of tetrahydropyran acetals promoted by trimethylsilyl trifluoromethanesulfonate: trichloroethylene as solvent for stereoselective C- and O-glycosylations.

Kendale, Joanna C / Valentín, Elizabeth M / Woerpel, K A

Organic letters

2014 Volume 16, Issue 14, Page(s) 3684–3687

Abstract: The selectivities of nucleophilic substitution reactions of tetrahydropyran acetals promoted by trimethylsilyl trifluoromethanesulfonate depend upon the reaction solvent. Polar solvents favor the formation of S(N)1 products, while nonpolar solvents favor ...

Abstract	The selectivities of nucleophilic substitution reactions of tetrahydropyran acetals promoted by trimethylsilyl trifluoromethanesulfonate depend upon the reaction solvent. Polar solvents favor the formation of S(N)1 products, while nonpolar solvents favor S(N)2 products. Trichloroethylene was identified as the solvent most likely to give S(N)2 products in both C- and O-glycosylation reactions.
MeSH term(s)	Acetals/chemistry ; Glycosylation ; Mesylates/chemistry ; Molecular Structure ; Solvents/chemistry ; Stereoisomerism ; Trichloroethylene/chemistry ; Trimethylsilyl Compounds/chemistry
Chemical Substances	Acetals ; Mesylates ; Solvents ; Trimethylsilyl Compounds ; trimethylsilyl trifluoromethanesulfonate (27607-77-8) ; Trichloroethylene (290YE8AR51)
Language	English
Publishing date	2014-07-03
Publishing country	United States
Document type	Journal Article ; Research Support, N.I.H., Extramural
ISSN	1523-7052
ISSN (online)	1523-7052
DOI	10.1021/ol501471c
Database	MEDical Literature Analysis and Retrieval System OnLINE

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Article: Concise epoxide-based synthesis of the C14-C25 bafilomycin A(1) polypropionate chain.

Valentín, Elizabeth M / Mulero, Marlenne / Prieto, José A

Tetrahedron letters

2012 Volume 53, Issue 17, Page(s) 2199–2201

Abstract: An efficient non-aldol convergent synthesis of the C14-C25 polyketide fragment of bafilomycin A(1) was completed in 16% overall yield and 8 steps in its longest linear sequence. This synthesis highlights the formation of the key fragments using a three- ... ...

Abstract	An efficient non-aldol convergent synthesis of the C14-C25 polyketide fragment of bafilomycin A(1) was completed in 16% overall yield and 8 steps in its longest linear sequence. This synthesis highlights the formation of the key fragments using a three-step sequence of epoxide cleavage, alkyne reduction, and epoxidation developed in our laboratory; starting from suitably protected enantiomeric epoxides of trans-2,3-epoxybutanol. This chemistry represents a quick asymmetric and diastereoselective construction of the polyketide chain of bafilomycin A(1), in which every stereogenic center was constructed using solely epoxide chemistry.
Language	English
Publishing date	2012-02-27
Publishing country	England
Document type	Journal Article
ZDB-ID	204287-3
ISSN	1873-3581 ; 0040-4039
ISSN (online)	1873-3581
ISSN	0040-4039
DOI	10.1016/j.tetlet.2012.02.067
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Article: Concise epoxide-based synthesis of the C14–C25 bafilomycin A₁ polypropionate chain

Valentín, Elizabeth M / Mulero, Marlenne / Prieto, José A

Tetrahedron letters. 2012 Apr. 25, v. 53, no. 17

2012

Abstract: An efficient nonaldol convergent synthesis of the C14–C25 polyketide fragment of bafilomycin A₁ was completed in 16% overall yield and 8 steps in its longest linear sequence. This synthesis highlights the formation of the key fragments using a three-step ...

Abstract	An efficient nonaldol convergent synthesis of the C14–C25 polyketide fragment of bafilomycin A₁ was completed in 16% overall yield and 8 steps in its longest linear sequence. This synthesis highlights the formation of the key fragments using a three-step sequence of epoxide cleavage, alkyne reduction, and epoxidation developed in our laboratory; starting from suitably protected enantiomeric epoxides of trans-2,3-epoxybutanol. This chemistry represents a quick asymmetric and diastereoselective construction of the polyketide chain of bafilomycin A₁, in which every stereogenic center was constructed using solely epoxide chemistry.
Keywords	alkynes ; chemical reactions ; chemical structure ; epoxides
Language	English
Dates of publication	2012-0425
Size	p. 2199-2201.
Publishing place	Elsevier Ltd
Document type	Article
ZDB-ID	204287-3
ISSN	1873-3581 ; 0040-4039
ISSN (online)	1873-3581
ISSN	0040-4039
DOI	10.1016/j.tetlet.2012.02.067
Database	NAL-Catalogue (AGRICOLA)

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