A new and improved synthesis of 19-iodocholesterol 3-acetate

Hadd, Harry E.

doi:10.1016/0039-128x(78)90027-2

Cited by 7 publications

(3 citation statements)

References 20 publications

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“…Under certain conditions 19-iodocholesterol has been shown to rearrange to 6fl-iodomethyl-19norcholest-5(10)-en-3fl-ol [12,13]. However, the nmr spectrum for 19-iodochoiesterol used in these studies agreed with published data [12,14]. The subsequent isotope exchange reaction was performed in refluxing acetone, conditions which are known to not cause rearrangement [15].…”

Section: Preparation Of 19=iodocholest-5-en-3fl-ol Oleatesupporting

confidence: 67%

A comparison of cholesteryl oleate and 19-iodocholesteryl oleate as substrates for adrenal cholesterol esterase

Nordblom

Schappa

Floyd

et al. 1980

Journal of Steroid Biochemistry

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Radiolabeled 19-iodocholesterol is widely used to obtain images of human adrenals. We have shown in rats and mice that 85-95% of the radiolabel is present in the esterified form. Using rat adrenal cytosolic cholesterol esterase, the kinetic parameters K~t and V were determined for commercially available cholesteryl [l-14C]-oleate (!) and [125I]-19-iodocholesteryl oleate (It). The Kra and V were found to be 16.2/zM and 602 pmol/min/mg prot. respectively for I compared to 76.2 ttM and 37.6 pmol/min/mg prot. for II. Since V/Ku is 37.3 ml/min/mg prot. for the normal ester and 0.49ml/min/mg prot. for the iodinated analog, it appears that the normal substrate is 76 times more specific than II. In addition, direct competition experiments were run in which 67/~M I was used as substrate. The addition of 65 and 325/tM 19-iodocholesteryl oleate caused 20 and 49% inhibition, respectively. On the basis of these studies, it is not surprising that 19-iodocholesterol would accumulate in the adrenals in an esterified form and thus provide an effective agent for adrenal visualization.

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Section: Preparation Of 19=iodocholest-5-en-3fl-ol Oleatesupporting

confidence: 67%

A comparison of cholesteryl oleate and 19-iodocholesteryl oleate as substrates for adrenal cholesterol esterase

Nordblom

Schappa

Floyd

et al. 1980

Journal of Steroid Biochemistry

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“…The synthesis of the novel detergent CHAPSTEROL requires inexpensive starting material and can be performed by a combination of well‐known and relatively simple synthetic steps [22,25–27]. The absorption spectrum of CHAPSTEROL in water consists of one peak at 210 nm due to the secondary amide function.…”

Section: Discussionmentioning

confidence: 99%

“…Starting with cholesteryl 3‐acetate, 19‐hydroxycholest‐5‐en‐3β‐yl acetate was prepared as described [25–27]. The further synthesis was similar to the synthesis of the bile acid derivative CHAPS described by Hjelmeland [22] and is shown in Fig.…”

Section: Synthesis Of Chapsterolmentioning

confidence: 99%

A novel cholesterol‐based detergent

Gehrig‐Burger¹,

Kohout

Gimpl³

2005

The FEBS Journal

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The plasma membrane of eukaryotic cells is a highly organized and dynamic structure. Lipids and proteins are asymmetrically distributed between the leaflets of the membrane bilayer. Several findings also indicate an asymmetrical distribution of lipids between lateral subdomains of the membrane. One such putative subdomain represent rafts, i.e. cholesterol-and sphingolipid-rich domains which can be isolated due to their resistance to solubilization with Triton X-100 at 4°C and their light buoyant density. A special form of rafts are caveolae, flask-shaped invaginations of the plasma membrane that are enriched in the scaffolding protein caveolin. Rafts and caveolae have been implicated in receptor-mediated signal transduction, receptor internalization, intracellular trafficking of cholesterol and cholesterol efflux. Several G protein-coupled receptors The study of integral membrane proteins often requires their purification. The first step in purifying membrane-spanning proteins is to solubilize them from the membrane. Water-soluble amphiphilic molecules (detergents) are used for this purpose. At low concentrations in aqueous solution, detergents exist as monomers. An important parameter of a detergent is its critical micelle concentration (CMC). Above the CMC, micelles are formed due to the amphiphilic nature of the detergent molecules. Amphiphilic membrane components, such as lipids and transmembrane proteins, become incorporated into these detergent micelles, and

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Replacement of Alcoholic Hydroxyl Groups by Halogens and Other Nucleophiles via Oxyphosphonium Intermediates

Castro

1983

Organic Reactions

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The Michaelis–Arbuzov reaction involves the formation of dialkyl alkylphosphonates by heating alkyl halides with trialkyl phosphites, via an intermediate phosphonium salt. In recent years it has been found that phosphonium salts can be formed by reaction of a variety of trivalent phosphorus compounds with oxidizing electrophiles, and that the resulting phosphonium intermediates can be trapped with an alcohol to form alkoxyphosphonium cations. These cations can then undergo nucleophilic displacements, either with their own counterions or with added nucleophiles. This chapter is limited to species formed in situ from trivalent phosphorus compounds and various oxidants. The most commonly used trivalent phosphorus compounds are triphenyl phosphite, triphenylphosphine, and tris(dimethylamino)phosphine. The most commonly used oxidants are molecular halogens, alkyl halides, carbon tetrahalides, N ‐haloamides, N ‐haloamines, and diethyl azodicarboxylate (DEAD). Other oxidants that have been used include mercuric salts, peroxides, dithioesters, and sulfenamides. The more common combinations of phosphorus(III) compounds and oxidants are summarized. The replacement of hydroxyl groups by halogen, the most common use of oxyphosphonium intermediates, is the principal subject of this chapter. However, the replacement of hydroxyl groups by oxygen, nitrogen, sulfur, and carbon nucleophiles is also discussed. This review is restricted to alcoholic hydroxyl groups, and does not include a discussion of carboxylic hydroxyl groups. The principal combinations covered are triphenylphosphine–diethyl azodicarboxylate, triphenyl phosphite–methiodide, triphenylphosphine–halogen, triphenylphosphine–tetrahalomethane, triphenylphosphine–N‐haloimide, and tris(dimethylamino)phosphine–tetrahalomethane. Some of these combinations have been discussed in recent reviews.

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A new and improved synthesis of 19-iodocholesterol 3-acetate

Cited by 7 publications

References 20 publications

A comparison of cholesteryl oleate and 19-iodocholesteryl oleate as substrates for adrenal cholesterol esterase

A comparison of cholesteryl oleate and 19-iodocholesteryl oleate as substrates for adrenal cholesterol esterase

A novel cholesterol‐based detergent

Replacement of Alcoholic Hydroxyl Groups by Halogens and Other Nucleophiles via Oxyphosphonium Intermediates

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