Phosphorus labeled, preparation

Fig. 31. SIMS plots of total deuterium density for n-type silicon specimens with various donor concentrations, deuterated by plasma gases at 300°C. Full curves are from recent measurements with one hour deuteration (Johnson, 1989) dashed curves are older data with two hour deuteration (Johnson, 1987). The donor for both these sets was phosphorus. The dotted curve shows data for one hour deuteration of a wafer with antimony doping. Each curve is labeled with its donor concentration in atoms/cm3. All sample surfaces were prepared in the same manner as those of Fig. 29. 

Kas, J., Rauch, P. Labeled Proteins, Their Preparation and Application, 112, 163-230 (1983). Keat, R. Phosphorus(III)-Nitrogen Ring Compounds. 102, 89-116 (1982). 

The phosphine 1-(1,2-C2BxoHii)P(CHs)2 was prepared and reacted with an iridium (I) complex, as shown in Fig. 27. Spectroscopic evidence strongly supported the view that the complexed Ir(I) had inserted into a B—H bond with the formation of an iridium-boron bond and an iridium-hydride link (58). Specific deuterium labels attached to the carborane moiety of the phosphine clearly proved this point. Thus, the B-H vertices of the icosahedral carborane group that are nearest the carbon atom bearing phosphorus were shown to be involved, although a distinction could not be made between the 3,6 or 4,5 sets of BH groups. 

Subsequent to recovery of the total lipids of a cellular preparation as a chloroform-soluble fraction, the total phosphorus content can be determined (see Chapter 3) and then, depending on the amount of lipid phosphorus (or whether the preparation is radiolabeled or not, see below), analytical and/or preparative thin-layer chromatography can be undertaken. In either case, if the experimental protocol is centered on a signal-transduction process, then there may be insufficient material for a phosphorus analysis. In the latter instance, the cellular preparation is prelabeled with 32P or [3H]inositol and the labeled products are located by autoradiography. A preferred type of adsorbent (for thin-layer chromatography) is Merck silica gel 60 (oxalate impregnated). An effective solvent for separation of the phosphatidylinosi-tols and other lipids is chloroform-acetone-methanol-acetic acid-water (80 30 26 24 14, v/v). The approximate / values of cellular phospholipids under these conditions are presented as follows ... 

Tagging DNA. (a) Suppose that you want to radioactively label DNA but not RNA in dividing and growing bacterial cells. Which radioactive molecule would you add to the culture medium (b) Suppose that you want to prepare DNA in which the backbone phosphorus atoms are uniformly labeled with 32p Which precursors should be added to a solution containing DNA polymerase I and primed template DNA Specify the position of radioactive atoms in these precursors. 

Buchwald, Friedman and Knowles succeeded in preparing 2,4-dinitrophenyl phosphate in which the three free oxygen atoms on phosphate were labeled stereospecifically with different isotopes of oxygen. Solvolysis of this compound in methanol and analysis of the methyl phosphate product showed that the reaction had proceeded with inversion of configuration at phosphorus (79). This remarkable experiment supports a concerted bimolecular displacement mechanism, with no metaphosphate intermediate, for the solvolysis of 2,4-dinitrophenyl phosphate in methanol. However, it does not rigorously exclude a stepwise mechanism in which a metaphosphate intermediate with a very short lifetime is formed and reacts with methanol faster than it rotates, and it does not provide direct evidence for a bimolecular, concerted reaction with solvent water. 

Synthesis of Phosphoric Acids and Their Derivatives. - A series of monoalkyl and dialkyl phosphorus acid chiral esters have been synthesised for use as carriers for the transport of aromatic amino acids through supported liquid membranes. The compounds acted as effective carriers but enantio-separation was at best moderate. A range of phosphono- and phosphoro-fluoridates have been prepared by treatment of the corresponding thio- or seleno- phosphorus acids with aqueous silver fluoride at room temperature (Scheme 1). In some cases oxidation rather than fluorination occurred. Stereospecifically deuterium-labelled allylic isoprenoid diphosphates, e.g. (1), have been synthesised from the corresponding deuterium-labelled aldehyde by asymmetric reduction, phosphorylation and Sn2 displacement with pyrophosphate (Scheme 2). ... 

As mentioned in the Section 1, physico-chemical methodology for quantitative analysis of plant hormone focuses primarily on GC-SIM, although HPLC with selective fluorescence detection continues to be used for lAA analysis in some laboratories. Procedures, such as the 2-methylindolo-a-pyrone assay for lAA analysis [82], are now rarely utilised. With the exception of ethylene quantification [2] there is little use of non-MS-based GC detection techniques, despite the fact that selective analysis at the picogram level is achieved for ABA with an electron capture detector [83], and lAA and cytokinins with a nitrogen phosphorus detector [84,85]. The reason for the demise of these GC procedures is that the detectors are destructive and this precludes the reliable recovery of labelled internal standards for radioassay and isotopic dilution analysis. The usual compromise was to take two aliquots of the purified samples, one for GC analysis and the other for the determination of radioactivity. The accuracy of this approach is dependent upon the questionable assumption that the radioactivity in the purified sample is associated exclusively with the compound under study. In an attempt to circumvent this problem, a double standard isotope dilution procedure was devised for the quantitative analysis of lAA in which one internal standard was used to correct for losses during sample preparation and a second for GC quantification [86]. This procedure was used in several... 

A simple procedure for the preparation of [ P]-labelled phosphorus oxychloride by equilibration of the unlabelled oxychloride with [ P]-orthophos-phoric acid has been described. This procedure should be extremely useful for the preparation of a variety of [ P]-labelled compounds and, for example, [ P]-labelled dolichyl phosphate has been prepared using this reagent. 

Chemical Synthesis.—Purine nucleoside 5 -monophosphates enriched with or 0 on the phosphate group are conveniently prepared by treating phosphorus pentachloride in dry triethyl phosphate with one equivalent of the appropriately labelled water to give PO]- or P 0]P0Cl3, which is not isolated but mixed with adenosine or guanosine in the same solvent. Work-up of the resulting 5 -phos-phorodichloridate in similarly labelled water permits the formation of pO]-or P 0]AMP (or GMP) in fair yield with good enrichment. The 5 -monophos-phates of the 5 -C-methyl uridines derived from 6-deoxy-D-allose and 6-deoxy-L-talose have been prepared via phosphorylation of the 2, 3 -0,0-ethoxymethyl-idene derivative of the nucleosides (1) with -cyanoethyl phosphate and DCC or TPS-Cl. The same method has been used to phosphorylate iV -benzoylated 2, 3 -0,C -isopropylidene derivatives of various 5 -C-alkyladenosine species (2) and also 4 -allyladenosine (3) as part of a study in which derivatives of AMP... 

Phosphorus-based olefin synthesis continues to be the method of choice for the preparation of retinals and related compounds. Reports include the s mthesis of retinal Schiff bases (115), the photoaffinity-labelled retinal (116), retinoic esters (117), and the acyclic analogue (118). However, earlier reports of the... 

Lowe and Tuck (1986) used PIX in the case of a nonenzymic substitution reaction at phosphorus that possibly involved a metaphosphate intermediate. These workers prepared ADP with label in the bridge position and incubated samples under a variety of reaction conditions. Should the P—O bond break and re-form, as expected if an ion pair involving metaphosphate formed, then PIX could be expected to occur. No PIX is observed in aqueous solution, but it does occur when acetonitrile is used as a solvent. However, the result in acetonitrile establishes the existence of an intermediate, but does not define its structure. The possibilities for the intermediate include an ion pair of metaphosphate and AMP, but do not preclude phosphorylated solvent and AMP as an alternative set of intermediates. 

When the polyene chain is extended from the ends towards the centre, acetic acid (9) is used as starting material. In a two-step, one-pot procedure, this can be converted into ethyl bromoacetate (10) by reaction with phosphorus tribromide and bromine in a Hell-Vollhardt-Zelinsky reaction [20,41], yielding the bromoacetyl bromide, which is subsequently quenched by adding ethanol, to give the labelled ethyl bromoacetate (W) in a yield of 86% [42]. Ethyl bromoacetate (10) is also available commercially in labelled form, but its preparation from acetic acid is an economically attractive alternative. 

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