- Development and application of a novel acridinium ester for use as a chemiluminescent emitter in nucleic acid hybridisation assays using chemiluminescence quenching
-
Chemiluminescent acridinium esters (AEs) permit the development of high sensitivity ligand binding assays due to a combination of high intensity light emission and very low backgrounds. Here these advantages are exploited for use in homogeneous nucleic acid hybridisation assays using quenched chemiluminescence. AE chemiluminescence is conventionally initiated at highly alkaline pH. Novel "active" AEs were designed that permit initiation under conditions compatible with maintenance of nucleic acid hybrids (i.e. pH less than 9). Methyl red was found to be a dark quencher species capable of functioning at this pH. Practical application of the chemiluminescence quenching assay system has been demonstrated using two model nucleic acid hybridisation assays based on intra- and intermolecular emitter/quencher pairs.
- Brown, Richard C.,Li, Zhaoqiang,Rutter, Andrew J.,Mu, Xiaojing,Weeks, Owen H.,Smith, Keith,Weeks, Ian
-
experimental part
p. 386 - 394
(2009/03/11)
-
- Design and synthesis of asymmetric acyclic phospholipid bolaamphiphiles
-
(Chemical Equation Presented) A synthetic route was devised for the generation of asymmetric lipid bolaamphiphiles through the sequential esterification of an alkyldioic acid, bearing distinct terminal protecting groups, with propanylamine and lyso-phosph
- Kai, Toshitsugu,Sun, Xue-Long,Faucher, Keith M.,Apkarian, Robert P.,Chaikof, Elliot L.
-
p. 2606 - 2615
(2007/10/03)
-
- Synthesis of saturated fatty acids 11C (13C)-labelled in the ω-methyl position
-
A method for the preparation of saturated fatty acids 11C (13C)-labelled in the ω-methyl position is described. A highly reactive zerovalent copper complex was prepared from lithium naphtalenide reduced lithium(2-thienyl)iodocuprate. The labelling precursors were obtained by addition of tert-butyl ω-iodocarboxylates to the organocuprate and these were reacted with [11C]methyl iodide to form 11C-labelled, protected intermediates. The tert-butyl ester protecting group was rapidly removed with trifluoroacetic acid, affording fatty acids 11C-labelled in the ω-methyl position. A solid phase extraction method was developed and preceded final HPLC purification. In a typical run starting with 2.75 GBq of [11C]methyl iodide, 375 MBq (66%) [16-11C]palmitic acid was obtained within 46 min from the end of radionuclide production.
- Neu, Henrik,Kihlberg, Tor,Langstroem, Bengt
-
p. 509 - 524
(2007/10/03)
-
- Synthesis of Very Long Fatty Acid Methyl Esters
-
Phosphoranes, produced by treating alkyltriphenylphosphonium bromides with lithium hexamethyldisilazide, reacted with ω-oxo esters to give modest yields of the corresponding methyl cis-alkenoates.By an alternative method, treatment of ω-iodo esters with the complexes formed from reactions of alkylcopper(I) and Grignard reagents gave methyl alkanoates, cis-alkenoates, and methylene-interrupted cis,cis-alka-dienoates and cis,cis,cis-trienoates.The stereochemical integrity of the esters was determined by 13C NMR spectroscopy.
- Kling, Marcel R.,Easton, Christopher J.,Poulos, Alf
-
p. 1183 - 1190
(2007/10/02)
-
- LACTONIZATION REACTIONS OF (Ω-CARBOXYALKYL)SULFONIUM SALTS
-
The intramolecular cyclizations of sulfonium salts having an ω-carboxyalkyl group were investigated for the synthesis of five- to nine-membered lactones, and five- to seven-membered lactones were obtained in good yields from S-(ω-carboxyalkyl)thiolanium salts.The scope and limitations of the synthetic utility of the reaction are indicated by this study. Key words: Lactonization reactions; (ω-carboxyalkyl)diphenylsulfonium salts; S-(ω-carboxyalkyl)thiolanium salts; medium-sized lactones; large-sized lactones; sulfur-containing lactones.
- Nakamura, Takako,Matsuyama, Haruo,Takahashi, Masaya,Kamigata, Nobumasa
-
-
- TRIMETHYLSILYL ESTERS: TEMPORARY PROTECTION OF CARBOXYLIC ACIDS DURING HYDROBORATION REACTIONS
-
Carboxylic acid are readily protected during hydroboration reactions by converting them to the corresponding trimethylsilyl esters.
- Kabalka, George W.,Bierer, Donald E.
-
p. 2783 - 2788
(2007/10/02)
-
- Intramolecular Cyclization of (ω-Carboxyalkyl)sulfonium Salts. A Novel Synthesis of Macrocyclic Lactones
-
A useful method for the synthesis of macrocyclic lactones using (ω-carboxyalkyl)sulfonium salts was developed.Base-catalyzed intramolecular cyclization of (ω-carboxyalkyl)diphenylsulfonium salts 2 gave simple macrocyclic lactones in high yields at high dilution conditions. (ω-Carboxyalkyl)alkylphenylsulfonium salts 8 afforded simple macrocyclic lactone 6a and alkyl carboxylates 9.The reactions of (ω-carboxyalkyl)dialkylsulfonium salts 10 gave only esters without lactonization product 6a.The cyclization of S-(ω-carboxyalkyl)thiolanium salts 3 and S-(ω-carboxyalkyl)-2-methylthiolanium salts 4 took place readily under similar conditions to afford sulfur-containing macrocyclic lactones 13 and 15, respectively, in good yields.To investigate the reaction mechanism, sulfonium salt 25, having an optically active carbon atom, was prepared.The intramolecular cyclization of 25 took place with an inversion of configuration at chiral carbon atom to give ricinelaidic acid lactone (26; optical purity 66percent).
- Matsuyama, Haruo,Nakamura, Takako,Kamigata, Nobumasa
-
p. 5218 - 5223
(2007/10/02)
-
- INTERPRETING SUBSTITUENT EFFECTS ON THE CRYSTAL PACKING OF LONG-CHAIN DIACYL PEROXXIDES. THE CRYSTAL STRUCTURES OF DI(11-BROMOUNDECANOYL) PEROXIDE AND DI(UNDECANOYL) PEROXIDE
-
Although crystals of di(11-bromoundecanoyl) peroxide and di(undecanoyl) peroxide have different space groups (P43212 and C2221), the molecules pack in almost identical layers.They differ only in the nature of stacking across interfaces involving the terminal groups.Because the 90 deg twist about the O-O bond locks neighboring molecules together within the layer, each peroxide shows a single solid phase from 5K to the melting point.Analysis of the stacking pattern in terms of the six possible orientational relationships suggests special stability for an L-shaped motif of C-Br...Br-C.Other substituents create different stackings of the same layer structure to give three crystal classes and five space groups among 14 compounds.Unsymmetrical peroxides are useful both for forcing a variety of substituted chains (particularly odd-even homologues) to pack with identical layer structures, and for controlling the stacking pattern.Because structural differences are localized in the vicinity of the substituents, this series of "substitutional polytypes" will allow systematic investigation of substituent effects on the physical and chemical properties of solids.
- McBride, J. Michael,Bertman, Steven B.,Cioffi, Donna Z.,Segmuller, Brigitte E.,Weber, Bruce A.
-
-
- Preparation of Macrocyclic Lactones by Ring Closure of Cesium Carboxylates
-
A series of ω-halo fatty acids, the longest being 16-iodohexadecanoic acid, was prepared by oxidation of the corresponding ketones with m-chloroperbenzoic acid in boiling chloroform, followed by ring opening usually with hydrogen iodide in acetic acid at 100 deg C.Solutions of these acids in dimethylformamide (DMF) at concentrations of 5E-3 - 5E-2 M were treated with an equivalent amount of dry Cs2CO3.The solutions were stirred at 40 deg C overnight.Workup of the reaction mixture produced a mixture of (macro)cyclic lactone (macrolide) and its dimer (dilide).For the case of 16-iodohexanoic acid the lactone was isolated in 85percent yield.Yields for other large ring macrolides were also excellent.It was demonstrated that substitution by carboxylate on a secondary halide also goes well to afford the corresponding macrolide with no detectable amount of elimination.The effects of ring size, concentration, and solvent on the ring closure of the cesium carboxylates formed in situ were investigated.DMF is the best solvent of those investigated for the ring closure.Cesium carboxylates also undergo more readily ring closure and in far better yield than the carboxylates of lithium, sodium, potassium, rubidium, silver, thallium, magnesium, strontium, or barium.The S-lactone of ricinelaidic acid was prepared optically pure in 80percent yield from optically pure mesylate of R-ricinelaidic acid, which was treated with cesium carbonate in dry DMF.This demonstrates that the ring closure proceeds with the anticipated SN2 inversion at the hydroxyl-bearing carbon atom.With the same approach optically pure S-zearalenone was protected and subjected to ring opening, and the hydroxyl group was activated as mesylate.Some racemization was found to occur in the ring-opening step.On treatment of this material with dry cesium carbonate in DMF, the desired ring closure took place in 80percent yield to provide an excess of the protected R enantiomer of zearalenone.On the basis of these results, some speculations are made concerning the action of cesium in promoting ring closure to macrocyclic lactones.
- Kruizinga, Wim H.,Kellogg, Richard M.
-
p. 5183 - 5189
(2007/10/02)
-