System silver perchlorate

Several other examples have been reported in which thioglycosides were used as glycosyl acceptors. Thus, thioglycosides containing free hydroxyls can be coupled chemoselectively with glycosyl bromides and chlorides in the presence of silver triflate or tin(II) chloride-silver perchlorate as the promoter system [12,53,56,162,218-221]. 

The solvolysis of 7,7-dibromo-bicyclo[4.1.0]heptane in methanol in the presence of silver perchlorate leads to ( -2-bromo-3-methoxycyeloheptene [172, 173]. A more detailed study of this reaction — having been performed by Ito in 1986 [174] — has revealed that the stereochemical result of the solvolysis depends on the length of the polymethylene chain in these bicyclic dihalides. For the lower homologs (n = 2 to 4) it is the ( )-isomer XIII that is produced, whereas for the more extended systems (n = 5 to 8) the Z-bromoethers XIV are produced. 

The acylation of aromatic ethers by acyl chlorides is highly regioselective in the presence of 10 mol% Sml3.53 Some aromatic compounds are efficiently acylated by acid anhydrides catalysed by niobium pentachloride with silver perchlorate.54 Arenes of a range of reactivity are acylated by acetic anhydride in a fluorous biphasic system catalysed by Hfps SCLCgFn L (1 mol%)55 The catalyst is easily recoverable and can usually be used again without decrease in activity. 

Mukaiyama, T, Takashima, T, Katsurada, M, Aizawa, H, A highly stereoselective synthesis of a-glucosides from 1-0-acetyl glucose by use of tin(lV) chloride-silver perchlorate catalyst system, Chem. Lett., 533-536, 1991. 

Toshima, K, Matsuo, G, Tatsuta, K, Efficient C-arylglycosylation of 1-O-methyl sugar by novel use of TMSOTf silver perchlorate catalyst system, Tetrahedron Lett., 33, 2175-2178, 1992. 

In some limited solvent systems, a metathetical reaction between triphenyl-bismuth dichloride and silver perchlorate results in the formation of oxybis-(triphenylbismuth) diperchlorate [72JOM(36)323]. This type of compound is only obtained when a mixture of water-benzene is used as the reaction medium. When the same reaction is carried out in absolute ethanol or in pure acetone, tetraphenylbismuthonium perchlorate and acetonyltriphenylbismuthonium perchlorate are obtained as the respective product (Section 3.3.1). 

Preparation of Macromolecular Dioxolenium Salts. Living polystyrene prepared by the polymerization of styrene in THF with a-methylstyrene tetramer dianion reacted with a 2.1-molar amount of ethylene oxide for three hours at room temperature a 6.6-molar amount of adipoyl chloride was added, and the mixture was stirred for 20 horns a 20-molar amount of ethylenebromohydrin was added. This mixture was stirred for 44 hours. The bromoethylated polystyrene was precipitated in excess methanol and freeze-dried from benzene in a vacuum system. A 1-nitropropane solution of polystyrene dioxolenium salt was prepared by reaction of bromoethylated polystyrene with silver perchlorate in 1-nitropropane. Silver bromide was removed from the reaction mixture by filtration. Molecular weight of the product was measured by a vapor-pressure osmometer it was 1910 for living polystyrene and 5190 for the bromoethylated polystyrene. Bromine analysis of the bromoethylated polystyrene showed 67.9% of the calculated value. 

Experimental conditions were developed that require the use of indium(lll) triflate (1% mol) in the acetylation of anisole with AAN in combination with silver perchlorate in acetonitrile at 50°C. 3 The reaction gives para-methoxyacetophenone in 82% yield, and better results, namely, 96% yield, can be achieved by increasing the lithium perchlorate amount (from 25% to 100%) in nitromethane at 50°C for 1 h. The catalytic system is highly effective for the acetylation of electron-rich aromatic and... 

Use of iodine-silver perchlorate may accomplish cation-radical formation before the oxidizing pair can themselves react. In modern usage, silver ion (as the perchlorate usually) is added to a solution of the substrate and iodine, and the complexity of the iodine-silver perchlorate system is avoided, provided that the substrate undergoes reasonably fast oxidation. Such is the case with perylene (Sato et al., 1969 Ristagno and Shine, 1971) and pheno-thiazine, but not the case with diphenylanthracene and thianthrene (Shine et al., 1972). 

Silver also has been demonstrated to be reactive in solution systems. Thus, silver perchlorate has been shown to influence the photochemical reactivity of stilbene in acetonitrile and methanol. The fluorescence of the stilbene is quenched on addition of the perchlorate and this is good evidence for the enhancement of the So-Ti crossing induced by the heavy ion Ag+. It seems likely that an Ag+/stilbene complex is formed. The perturbation of the system is better in methanol than in acetonitrile. However, cis.trans isomerism of the stilbene is reduced within the excited Ag+/stilbene complex since it is difficult for the geometrical isomerism to occur. Enhanced isomerism is observed with the Ag+/azobenzene system. In this complex there are steiic problems encountered in the nitrogen rehybridization process that is operative in the isomerism . Enhanced So-T crossing is also seen in the Ag+/1 1 complex with tryptophan where the fluorescence is quenched and there is a threefold increase in phosphorescence . Complexes between Ag+ and polynucleotides and DNA cause quenching of the fluorescence. Enhancement of phosphorescence and a 20-fold increase in the dimerization of thymine moieties has also been observed when silver ions are added to the reaction system . ... 

C-1. The product distribution was found to depend upon the amount of water present in the system, more 6-(bromomethylene)cyclodecanone being obtained with less water present. This observation was explained in terms of capture of the carbonium ion formed from (56 = 2). There would seem to be no examples yet where an intramolecular shift process competes with ring-opening of a cyclopropyl cation. Solvolysis of 10,10-dibromo[4,3,l]propellane in acetic acid-sodium acetate-acetic anhydride gave products formed via the strained bicyclic acetate (56 n = 1, R = Ac). In the absence of acetic anhydride products derived from the corresponding alcohol (56 n = 1, R — H) were obtained as well. Solvolyses of 10,10-dibromo[4,3,l]propell-3-ene in acetic acid-sodium acetate, in the presence and absence of acetic anhydride, and in acetic acid-silver perchlorate, were also reported. Most of the products may have been formed by reaction pathways similar to those observed for (55). ... 

Silica microrods with nanosized pores were explored by Li et al. [115] templated in the microemulsion system with water/TX-100/[bmim][PFJ. Synthesis of silver (Ag) nanoparticles by the photoreduction of silver perchlorate (AgClO ) in water-in-ionic liquid microemulsions of water/Tween-20/([bmim][BFJ) and l-octyl-3-methylimid-azolium tetrafluoroborate ([omim][BFJ) was reported by Harada et al. [116]. The average diameters of the metalhc Ag particles were 8.9 and 4.9nm in the water-in-([bmim][BF ]) and water-in-([omim][BFJ) microemulsions, respectively. We have [117] synthesized CdS nanoparticles in a bicontinuous-type microemulsion in the system comprising water/lL-2-HlP (1 l-wt./wt.)/IPM as 6.8/86.6/6.6wt.%. Particle diameter of approximately 3.2 nm had marginal semiconductivity and moderate antibacterial activity against E. coli. Li et al. [118] synthesized tetragonal ZrO ... 

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