The chemistry of 2-methyltetrahydropyran-4-one: An L-Selectride reaction that gives predominantly the equatorial alcohol

1978 ◽  
Vol 56 (6) ◽  
pp. 789-793 ◽  
Author(s):  
Donald C. Wigfield ◽  
Steve Feiner
Keyword(s):  
Proton Nmr ◽  
Reducing Agents ◽  
Cyclic Ether ◽  
Nmr Analysis ◽  
Ether Oxygen

The stereoisomers of 2-methyltetrahydropyran-4-ol have been separated and identified by carbon-13 and proton nmr analysis of the trideuteriomethyl-2,6,6-trideuterio analogue. Stereoisomeric product ratios of reduction of 2-methyltetrahydropyran-4-one (1) by NaBH4, KBH4, L-Selectride, K-Selectride, and LiBH(nBu)3 have been determined and compared with reductions of 3-methylcyclohexanone. Product ratios in the reduction of the two substrates by the borohydride reducing agents are similar but are quite different in the reduction by the Selectride reducing agents, 1 being reduced by Selectride to give 73% equatorialalcohol. Two possible mechanisms of reduction of 1 are proposed, involving intramolecular assistance by the cyclic ether oxygen.

Participation of 19-ester groups in the cleavage of 2α,3α- and 5α,6α-steroid epoxides. A case of competition between participation and external nucleophile attack

1979 ◽  
Vol 44 (5) ◽  
pp. 1496-1509 ◽  
Author(s):  
Pavel Kočovský ◽  
Václav Černý
Keyword(s):  
Perchloric Acid ◽  
Hydrobromic Acid ◽  
Ester Group ◽  
Carbonyl Oxygen ◽  
Cyclic Carbonate ◽  
Cyclic Ether ◽  
Normal Reaction ◽  
Neighboring Group ◽  
Ether Oxygen ◽  
The Difference

Acid cleavage of the acetoxy epoxide IIIa with aqueous perchloric acid or hydrobromic acid gave two types of products, i.e. the diol Va or the bromohydrin VIa, and the cyclic ether VIII. The latter compound arises by participation of ether oxygen of the ester group. On reaction with perchloric acid the epoxide IVa gave the diol XIIIa as a product of a normal reaction and the isomeric diol Xa as a product arising by intramolecular participation of the carbonyl oxygen of the 19-acetoxy group. Participation of the 19-ester group is confirmed by the formation of the cyclic carbonate XI when the 19-carbonate IVb is treated analogously. On reaction with hydrobromic acid, the epoxide IVa gave solely the bromohydrin XIVa as a product of the normal reaction course. Discussed is the similarity of these reactions with electrophilic additions to the related 19-acetoxy olefins I and II, the mechanism, the difference in behavior of both epoxides III and IV, the dependence of the product ratio on the nucleophility of the attacking species, and the competition between participation of an ambident neighboring group and an external nucleophile attack.

scholarly journals NMR lipid profiles of cells, tissues, and body fluids: proton NMR analysis of human erythrocyte lipids.

1994 ◽  
Vol 35 (11) ◽  
pp. 1925-1931
Author(s):  
R K Adosraku ◽  
G T Choi ◽  
V Constantinou-Kokotos ◽  
M M Anderson ◽  
W A Gibbons
Keyword(s):  
Human Erythrocyte ◽  
Proton Nmr ◽  
Body Fluids ◽  
Lipid Profiles ◽  
Nmr Analysis ◽  
Erythrocyte Lipids

Proton NMR analysis of plasma is a weak predictor of coronary artery disease

2006 ◽  
Vol 12 (6) ◽  
pp. 705-710 ◽  
Author(s):  
Heide L Kirschenlohr ◽  
Julian L Griffin ◽  
Sarah C Clarke ◽  
Ranyl Rhydwen ◽  
Andrew A Grace ◽  
...  
Keyword(s):  
Coronary Artery Disease ◽  
Coronary Artery ◽  
Proton Nmr ◽  
Nmr Analysis ◽  
Artery Disease

Carbon-13 and proton NMR analysis of isotopically labeled benzo[a]pyrenes

1983 ◽  
Vol 105 (4) ◽  
pp. 733-735 ◽  
Author(s):  
Clifford J. Unkefer ◽  
Robert E. London ◽  
Thomas W. Whaley ◽  
Guido H. Daub
Keyword(s):  
Proton Nmr ◽  
Nmr Analysis

A Quantitative NMR Method for Silyllithium Analysis

Synlett ◽  
2017 ◽  
Vol 28 (18) ◽  
pp. 2449-2452
Author(s):  
Scott Sieburth ◽  
Yingjian Bo
Keyword(s):  
Proton Nmr ◽  
Relative Quantification ◽  
Nmr Analysis ◽  
Quantitative Nmr ◽  
Simple Method ◽  
Nmr Method

A rapid and extremely simple method for silyl anion analysis is presented. The progress of silyllithium reagent preparation can be determined by quenching an aliquot with neat chloro(trimethyl)silane, evaporation, dilution with CDCl3, and direct proton NMR analysis. This procedure is fast, simple, and allows for identification and relative quantification of the starting reagent, intermediates, and the silyllithium product.

Ex Vivo Proton NMR Analysis and Characterization of Thymus Lipid Metabolites and their Variation with Age in C57BL/6 Mice

2011 ◽  
Vol 4 (1) ◽  
pp. 57-69
Author(s):  
Iago Pinal-Fernandez ◽  
Manuel Martin-Pastor ◽  
Pedro Ferro-Gallego ◽  
Lourdes Dominguez-Gerpe
Keyword(s):  
Ex Vivo ◽  
Proton Nmr ◽  
Nmr Analysis ◽  
Lipid Metabolites

A proton NMR analysis of the OCH3 group conformation in 2-methoxypyridines

1982 ◽  
Vol 20 (1) ◽  
pp. 40-41 ◽  
Author(s):  
R. H. Contreras ◽  
J. C. Facelli ◽  
D. G. de Kowalewski
Keyword(s):  
Proton Nmr ◽  
Nmr Analysis ◽  
Och3 Group
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