1- -pyridinium bromid

Amino-5-nitrosopyrimidines also condense with benzoylacetonitrile, phenacyl-pyridinium bromide and acetonylpyridinium chloride in the presence of sodium cyanide to produce. 7-amino-6-pteridinyl ketones (63JOC1197). Pteridine syntheses from pyridinium salts are not limited to the preparation of pteridyl ketones since pyridinium acetamide... 

Pyridinium bromide, N-phenacyl-NMR, 2, 121 reactions, 2, 336 Pyridinium cations metabolism, 1, 234 reactivity, 2, 167 Pyridinium chloride hydrogenation, 2, 284 Pyridinium chloride, N-acyl-as acylating agent, 2, 180 Pyridinium chloride, cetyl-as antiseptic, 2, 519... 

Pyridine hydrobromide perbromide (pyridinium bromide perbromide) [39416-48-3] M 319.9, m 130 (dec), 132-134 (dec). It is a very good brominating agent - liberating one mol. of Br2. Purified by recrystn from glacial acetic acid (33g from lOOmL of AcOH). [Fieser and Fieser Reagents for Organic Chemistry Vol 1 967 1967.]... 

Acetoxyandrost-5-en-17-one (59) is converted into the ethylene ketal (60) by treatment with ethylene glycol, triethylorthoformate and p-toluenesulfonic acid. The ketal is brominated with pyridinium bromide perbromide in THF and then treated with sodium iodide to remove bromine from the 5 and 6 positions. This gives the 16a-bromo compound (61) which is hydrolyzed in methanol to the free alcohol (62). Dehydrobromination is effected with potassium Fbutoxide in DMSO to give the -compound (63). Acid catalyzed hydrolysis of the ketal in aqueous acetone gives the title compound (64). ... 

Intramolecular nucleophilic displacement of the bromo group by an azine-nitrogen occurs in the cyclization of A-2-quinaldyl-2-bromo-pyridinium bromide (248) to give the naphthoimidazopyridinium ring system. The reaction of 2-bromopyridine and pyridine 1-oxide yields l-(2-pyridoxy)pyridinium bromide (249) which readily undergoes an intramolecular nucleophilic substitution in which departure of hydrogen as a proton presumably facilitates the formation of 250 by loss of the JV-oxypyridyl moiety. 

The intramolecular cyclization of enolate of l-tryptophyl-3-((3-ketobutyl) pyridinium bromide (160) afforded enamine 161, which undergoes stereoselective acid cyclization with cone. HCl to give the pentacyclic ketone 162 (Catalytic hydrogenation of 162 led to (d,l)-pseudoyohimbone (163) (76JA3645). Again, H3-H15 were found to have the tmns configuration in 162. 

The reaction product (1-carbethoxymethyM-carbomethoxy-pyridinium bromide) was obtained in crystalline form. (It formed prisms melting at 166°-169°C after recrystallization from a mixture of isopropanol and acetone.) It was not necessary to isolate it. For the following reduction step, the reaction mixture was brought into solution by the addition of about 1 liter of warm ethyl alcohol. It was then hydrogenated at about 30 atm pressure in the presence of 2 g of platinum oxide. The temperature rose during this reaction to about 40°C. 

Benzamido-1 -[2-(3-indolyl)ethyl] pyridinium bromide Hydrogen... 

To a solution of 60 g of potassium xanthogenate in 240 cc of water there is added dropwise, while being cooled with ice, a solution of 42 g of 3,4-bis-bromomethyl-4-hydroxy-5-methyl-pyridinium-bromide In 1 liter of water so that the temperature remains between 2°C and 5°C. After stirring for 1 hour at the same temperature, the water is decanted off and the residue is triturated with acetone. Yield 25 g of 4-hydroxymethyl-5-hydroxy-6-methyl-pyridyl-(3)-methy I xanthogenate melting point 170°C to 171°C (alcohol, decomposition). 

Treatment of 2,7-di-/ert-butylthiepin (1) either directly with bromine at — 78 °C, or with pyridinium bromide perbromide at room temperature, gives the thiophene compound 2. In contrast, bromination with bromine-1,4-dioxane complex or pyridinium bromide perbromide in the presence of acetic acid leads to the thiopyran derivative 3.87 To account for these results a homothiopyrylium ion has been proposed as a common intermediate, formed by electrophilic bromination at C4 in the first step. 

A stirred solution of methyl 2-(benzylamino)benzoate (12.6 g, 52 mmol) and pyridine (4.2 g, 53 mmol) in Et20 (500 inL) was slowly treated with bromoacetyl bromide (10.6 g, 52.5 mmol). Stirring was continued for 2 h, the precipitated pyridinium bromide was filtered off and the filtrate was evaporated under reduced pressure. The resulting syrupy methyl 2-[benzyl(bromoacetyl)aimno]benzoate was dissolved in MeOH (1 L) and the solution was saturated with NH, at 20 C and left for 8 h. The solution was evaporated in vacuo and the residue was crystallized (CH2C12/Et20) yield ll.Og (79%) mp 189-190 C. 

Reaction of 9-vinylcarbazole with bromine in benzene or ethanol gave the 3,6-dibromo derivative [84AHC(35)83]. Pyridinium bromide perbro-mide gave a 72% yield of the 3-bromo derivative of 2,4-dimethoxycarba-zole. With other reagents mixtures of 3- and 5-bromo-, 3,5- and 3,7-dibromo products were formed. The 5-bromo- and 3,6-dibromo- compounds rearranged quantitatively to the 3- and 3,7-isomers [92JCR(S)2]. 

Studies of halogenation of the partially reduced systems (e.g., 148) have shown that the 6- (148) or 8-nitro-2,3-dihydrothiazolo[3,2-a]pyridinium bromides were brominated in hydroxylic solvents with a regiochemistry and ease of reaction consistent with the intermediacy of a pseudo base... 

Further organic storing materials Phenyl bromide [14], pyridine, 1 -picoline, 2,6-lutidine [15-17] Arsonium salts [18, 19] Phosphonium salts [20] Pyridinium bromides [21] Aromatic amines [22] Urotropin-bromine adduct [23] Pyridinium and sulfonium salts [24] Propionitril [25]... 

A merocyanine dye, l-ethyl-4-(2-(4-hydroxyphenyl)ethenyl)pyridinium bromide (M-Mc, 2), exhibits a large spectral change according to the acid-base equilibrium [40, 41]. The equilibrium is affected by the local electrostatic potential and the polarity of the microenvironment around the dye. Hence, this dye is useful as a sensitive optical probe for the interfacial potential and polarity when it is covalently attached to the polyelectrolyte backbone. 

Morishima et al. [42] prepared polyanions (A-x, 3) of various charge densities tagged with the merocyanine dye (Me) by terpolymerization of acrylic acid (AA), acrylamide (AAm), and a small mole fraction of l-(2-methacryloyloxyethyl)-4-(2-(4-hydroxyphenyl)ethenyl)pyridinium bromide (MA-Mc). Since these polyanions carry only 1 mol% of the MA-Mc units, they can practically be treated as copolymers of AA and AAm with a wide range of composition. 

CisHisLNjO 154371-62-7) see Eprosartan tert-butyl 4,4 -dimethoxy-a-stilbenyl sulfide (C20H24O2S) see Raloxifene hydrochloride tert-butyl 4,4 -dimethoxy-a-stilbenyl sulfoxide (C20H24O3S 186408-54-8) see Raloxifene hydrochloride l-butyl-2-(2,6-dimethylanilinocarbonyl)pyridinium bromide... 

Trimethylsilyl iodide 17, which can be generated in situ by reaction of trimethyl-silyl chloride (TCS) 14 with Nal in acetonitrile [1], converts alcohols 11, in high yields at room temperature, into their iodides 773a, HI, and hexamethyldisiloxane (HMDSO) 7 [1-8, 12]. Likewise esters such as benzyl benzoate are cleaved by Me3SiCl 14/NaI in acetonitrile under reflux [Ij. Reactions of alcohols 11 with trimethylsilyl bromide 16 in chloroform or, for in situ synthesis of 16 from liBr and TCS 14 in acetonitrile and with HMDS 2 and pyridinium bromide perbromide, proceed only on heating in acetonitrile or chloroform to give the bromides 773 b in nearly quantitative yield [3, 8, 12] (Scheme 6.1). 

A wide variety of aromatic compounds can be brominated. Highly reactive ones, such as anilines and phenols, may undergo bromination at all activated positions. More selective reagents such as pyridinium bromide perbromide or tetraalkylammonium tribromides can be used in such cases.18 Moderately reactive compounds such as anilides, haloaromatics, and hydrocarbons can be readily brominated and the usual directing effects control the regiochemistry. Use of Lewis acid catalysts permits bromination of rings with deactivating substituents, such as nitro and cyano. 

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