Stereochemistry of Reduction of Ketones by Complex Metal Hydrides

Wheeler, Owen H.; Mateos, J. L.

doi:10.1139/v58-210

Cited by 36 publications

(14 citation statements)

References 16 publications

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“…The very long chain fatty acids occur predominantly in the acyl chain. Deuterated cholesterol (3␣,3␤-ol-cholesterol-d2) was prepared from cholest-5-en-3␤-on essentially according to a published procedure (Wheeler and Mateos, 1958). The product purity was checked by TLC and 1 H-NMR.…”

Section: Methodsmentioning

confidence: 99%

A Solid-State NMR Study of Phospholipid-Cholesterol Interactions: Sphingomyelin-Cholesterol Binary Systems

Guo

Kurze

Huber

et al. 2002

Biophysical Journal

103

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We used solid-state NMR techniques to probe the interactions of cholesterol (Chol) with bovine brain sphingomyelin (SM) and for comparison of the interactions of Chol with dipalmitoylphosphatidylcholine (DPPC), which has a similar gel-to-liquid crystalline transition temperature. (1)H-, (31)P-, and (13)C-MASNMR yielded high-resolution spectra from multilamellar dispersions of unlabeled brain SM and Chol for analysis of chemical shifts and linewidths. In addition, (2)H-NMR spectra of oriented lipid membranes with specific deuterium labels gave information about membrane ordering and mobility. Chol disrupted the gel-phase of pure SM and increased acyl chain ordering in the liquid crystalline phase. As inferred from (13)C chemical shifts, the boundaries between the ordered and disordered liquid crystalline phases (L and L) were similar for SM and DPPC. The solubility limit of Chol in SM was ~50 mol %, the same value as previously reported for DPPC membranes. We found no evidence for specific H-bonding between Chol and the amide group of SM. The order parameters of a probe molecule, d31-sn1-DPPC, in SM were slightly higher than in DPPC for all carbons except the terminal groups at 30 mol % but were not significantly different at 5 and 60 mol % Chol. These studies show a general similarity with some subtle differences in the way Chol interacts with DPPC and SM. In the environment of a typical biomembrane, the higher proportion of saturated fatty acyl chains in SM compared to other phospholipids may be the most significant factor influencing interactions with Chol.

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Section: Methodsmentioning

confidence: 99%

A Solid-State NMR Study of Phospholipid-Cholesterol Interactions: Sphingomyelin-Cholesterol Binary Systems

Guo

Kurze

Huber

et al. 2002

Biophysical Journal

103

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“…Cholesterol, cholest-5-en-3-on, LiAlD 4 and deuterated tert-butanol ((CH 3 ) 3 COD) were also purchased from Sigma-Aldrich. Deuterated cholesterol (␤-(3-2 H)-cholesterol) was prepared from cholest-5-en-3-on essentially according to a published procedure (Wheeler and Mateos, 1958). Briefly, 100 mg LiAlD 4 was dissolved in 8 ml carefully dried tetrahydrofuran, and 0.5 ml (CH 3 ) 3 COD was slowly added while stirring at 0°C.…”

Section: Chemicalsmentioning

confidence: 99%

A 2H NMR Study of Macroscopically Aligned Bilayer Membranes Containing Interfacial Hydroxyl Residues

Kurze

Steinbauer

Huber

et al. 2000

Biophysical Journal

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The polar interface of membranes containing phosphatidylglycerol or cholesterol was studied by (2)H nuclear magnetic resonance (NMR) as a function of membrane hydration. The membranes were macroscopically aligned and hydrated with deuterium oxide. Water uptake and membrane annealing was achieved under NMR control, using a novel hydration technique. Well-resolved (2)H quadrupolar doublets were obtained from individual hydroxyl residues and from the interlamellar water. The response of the phosphatidylglycerol headgroup and of the cholesterol molecule to the spontaneous evaporation of interlamellar water could be thus monitored continuously. It is shown that the phosphatidylglycerol headgroup undergoes changes of conformation and average orientation with respect to the membrane surface and that the off-axis motion of the cholesterol molecule decreases. The deuteron exchange between hydroxyl residues and surface-associated D(2)O was determined by an inversion transfer technique. The exchange rates of the hydroxyl residues in the phosphatidylglycerol headgroup were different and depended strongly on the total hydration of the membrane. Significantly lower and almost hydration-independent rates were obtained for cholesterol. These results will be discussed with reference to earlier reports on the headgroup dynamics of phosphatidylglycerol and on the interaction of cholesterol with the membrane-water interface.

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“…Benzyl alcohols which were not commercially available and the a,a-dideuterated analogues of the benzyl alcohols were prepared by reduction of the corresponding benzoic acid or the methyl ester (65,66). …”

Section: Methodsmentioning

confidence: 99%

Solvolysis of 2-substituted-9-(otrho-substituted phenylmethyl)fluoren-9-yltrimethylammonium ions in various solvents. The effect of steric crowding on alkene formation

Smith¹,

Pradhan²

1986

Can. J. Chem.

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The solvolytic reaction of several 9-(ortho-substituted phenylmethy1)fluoren-9-yltrimethylammonium salts has been investigated in several different solvents. Substitution and elimination products were found for the reactions in all the solvents studied, with the exceptions that reaction in both tert-butyl alcohol and chloroform led exclusively to the alkene product. The observed rate constants for alkene formation and the percent alkene were measured and it was found that the di-ortho compounds reacted at a faster rate but produced less alkene than the reaction of the corresponding mono-ortho salts. Hydrogen-deuterium isotope effects were also determined for the various reactions. The results are discussed in terms of the reaction proceeding by way of the El mechanism, where steric acceleration promotes the loss of the bulky ammonium leaving group to give the carbocation intermediate. Op6rant dans plusieurs solvants, on a, ktudik la &action solvolytique de plusieurs sels trimkthylammonium des (phknylmkthyles substituks en ortho)-9 fluorbne-9 yles. A l'exception des rkactions dans l'alcool tert-butylique ou dans le chloroforme, toutes les rkactions ktudikes dans les autres solvants ont conduit L la formation de produits de substitution ainsi que d'klimination. On a mesurk les constantes de vitesse pour la formation des alcbnes ainsi que les pourcentages d'alcbnes formks; on a trouvk que les composks doublement substituks en ortho dagissent plus rapidement mais qu'ils produisent moins d'alcbnes que les rkactions des sels correspondants qui ne portent qu'un substituant en ortho. On a dkkrmink les effets cinktiques hydrogbne-deutkrium pour diverses &actions. On discute des ksultats en fonction d'une reaction qui se produirait par le biais d'un mkcanisme E l et dans lequel l'accklkration stkrique favoriserait le perte du nuclkofuge ammonium encombrant au profit de la formation d'un carbocation intermkdiaire. PETER JAMES SMITH[Traduit par la revue]

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Stereochemistry of Reduction of Ketones by Complex Metal Hydrides

Abstract: The stereochemistry of the reduction of a number of cyclic ketones with complex metal hydrides has been determined. 111 the absence of any large steric effect in the ketones, the reduction is essentially stereospecihc, giving the more stable alcohol.

Cited by 36 publications

References 16 publications

A Solid-State NMR Study of Phospholipid-Cholesterol Interactions: Sphingomyelin-Cholesterol Binary Systems

A Solid-State NMR Study of Phospholipid-Cholesterol Interactions: Sphingomyelin-Cholesterol Binary Systems

A 2H NMR Study of Macroscopically Aligned Bilayer Membranes Containing Interfacial Hydroxyl Residues

Solvolysis of 2-substituted-9-(otrho-substituted phenylmethyl)fluoren-9-yltrimethylammonium ions in various solvents. The effect of steric crowding on alkene formation

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