Synthesis of [14α‐methyl‐<sup>3</sup>H]‐24,25‐dihydrolanosterol

Dekeczer, Steve; Kertesz, Denis J.; Parnes, Howard L.

doi:10.1002/jlcr.2580330308

Cited by 6 publications

(4 citation statements)

References 18 publications

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Section: Resultsmentioning

confidence: 99%

“…35 Δ 7,8 -Sterols with a single C-4 methyl group (lophenol) can be found naturally 36,37 and have been the target of recent synthetic work 38 as they act as competitive inhibitors of 14α-demethylases. [39][40][41][42] Both 10 and 11 were obtained alongside their Δ 7,8 -analogues. The two alkene isomers (Δ 7,8 & Δ 8,9 ) for all compounds proved to be inseparable by most chromatographic techniques including argentic TLC.…”

Section: Resultsmentioning

confidence: 99%

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Synthesis of obtusifoliol and analogues as CYP51 substrates

2022

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Synthesis of obtusifoliol and analogues as CYP51 substrates

2022

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“…Tritiated formaldehyde can be prepared at high specific activity in situ either by catalytic reduction of hydrogen cyanide with tritium gas over 5% Pd/BaSO 4 in aqueous methanol 311 , or by reduction of CO 2 in THF with ZrCp 2 Cl 3 H (tritiated Schwartz Reagent) 322 ( Figure 4.98) (see Section 4.3.12 and Reference 272a). The latter procedure can also be used to isolate the reagent in free form by vacuum transfer if THF is replaced by a high-boiling ether 278a .…”

Section: Tritiated Formaldehyde ( 3 Hcho 3 Hc 3 Ho)mentioning

confidence: 99%

Preparation of Tritium‐Labeled Compounds by Chemical Synthesis

2009

Preparation of Compounds Labeled With Tritium and Carbon‐14

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In contrast to isotope exchange methods, which utilize the target compound or a late intermediate as substrate for labeling, chemical synthesis involves transformation of some precursor chemical with concurrent introduction of tritium. Four basic types of transformations are distinguished for discussion each in turn. They are catalytic tritiations (Section 4.1), which usually involve the reduction of a precursor compound using a catalyst and tritium gas; catalytic tritiolyses (Section 4.2), involving the replacement of functional groups by tritium, again using a catalyst and tritium gas; tritide reductions (Section 4.3), utilizing tritiated versions of hydridic reducing reagents; and the use of small tritiated building blocks (Section 4.4) in synthetic operations to construct target molecules.A phenomenon strongly relevant to the catalytic methods discussed in Sections 4.1 and 4.2, and of some relevance also for tritide chemistry (Section 4.3) is solvent exchange. Most catalytic tritiations and tritiolyses are conducted in solution, and a wide variety of solvents have been used, ranging from nonpolar ones to highly polar, hydroxylic media. The properties of the solvent, however, influence not only the course and rate of a heterogeneously catalyzed reaction, but also the extent to which solvent hydrogen may exchange with tritium gas as a side reaction and thereby dilute the isotope introduced into the substrate: solvent exchange. It is commonly recognized that the use of protic solvents for tritiations and tritiolyses increases the risk of obtaining products of less than maximal specific activity, although it is equally clear that such reactions often succeed without dilution of label. The crucial factor in each experiment is the relationship between the rate of the tritium-incorporation reaction and the rate(s) of any tritium-diluting reaction(s). It is documented that the rate of metal-catalyzed exchange between elemental hydrogen and water is significant, especially at low pH 1 , but little quantitative data are available to guide practice. Recently a turnover number of 17.3 h À1 was reported for the exchange between H 2 and 2 H 2 O catalyzed by 10% Pd/C at room temperature and a pressure of 1 atm 2 ; this is rapid enough to provide the basis for an economical method of catalytic deuterium exchange Preparation of Compounds Labeled with Tritium and Carbon-14 Rolf Voges, J. Richard Heys and Thomas Moenius

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“…14 For example, Dekeczer et al have successfully synthesized labeled lanosterol derivatives by electrochemical reduction. 15 In general, electrosynthesis is performed using a beaker-type electrochemical cell. However, the reaction volume is limited to the volume of the beaker-type cell, so that repeated electrolyses are required, if a large amount of the product is necessary.…”

Section: Introductionmentioning

confidence: 99%