Pyridyl oxides

A -2-Picolylamine -Oxide R2NCH2-2-pyridyl -Oxide (Chart 10)... 

Recendy, PEN, a-4-pyridyl-oxide-N-t-butyl nitrone (POEN) or 5-5,dimethyl-1, pyrroline-N-oxide (DMPO) were evaluated in models of experimental shock (endo-toxic, traumatic and mesenteric artery occlusion in rats). All three nitrones, when given prior to the insult intraperitoneally, were protective. When the nitrone s spin trapping ability was inactivated by exposure to solar light and air, they were no longer efficacious (Novelli, 1992). 

Relatively little information is available concerning the pharmacokinetics of this series of compound.s. Tripelenna-mine is metabolized in humans by N-glucuronidation. N-otidation. and pyridyl oxidation followed by phenol gluc-utonidation. It is anticipated that other members of this scries IK similarly metabolized. ... 

A sensitive method for the flow injection analysis of Cu + is based on its ability to catalyze the oxidation of di-2-pyridyl ketone hydrazone (DPKH) by atmospheric oxygen. The product of the reaction is fluorescent and can be used to generate a signal when using a fluorometer as a detector. The yield of the reaction is at a maximum when the solution is made basic with NaOH. The fluorescence, however, is greatest in the presence of HCl. Sketch an FIA manifold that will be appropriate for this analysis. 

Derivatives such as 3-fluoro-4-nitropyridine [13505-01 -6] (396) or the 1-oxide [769-54-0] (397) have been used to characteri2e amino acids and peptides. 5-Eluoro-3-pyridinemethanol [22620-32-2] has been patented as an antihpolytic agent (398). A promising antidepressant, l-(3-fluoro-2-pyridyl)pipera2ine hydrochloride [85386-84-1] is based on 2-chloro-3-fluoropyridine [17282-04-1] (399). 

Adenine, 3-methyl-9- -D-ribofuranosyl-synthesis, 5, 586 Adenine, 2-methylthio-oxidation, 5, 561 Adenine, 2-phenyl-synthesis, 5, 569 Adenine, 2- -pyridyl-synthesis, 5, 569 Adenine, 8-ribofuranosyl-synthesis, 5, 585 Adenine, 3- -D-ribofuranosyl-synthesis, 5, 595... 

Ethylene, /3-(dimethylamino)-nitro-in pyrrole synthesis, 4, 334 Ethylene, dithienyl-in photochromic processes, 1, 387 Ethylene, furyl-2-nitro-dipole moments, 4, 555 Ethylene, l-(3-indolyl)-2-(pyridyl)-photocyclization, 4, 285 Ethylene, l-(2-methyl-3-indolyl)-l,2-diphenyl-synthesis, 4, 232 Ethylene, (phenylthio)-photocyclization thiophenes from, 4, 880 Ethylene carbonate C NMR, 6, 754 microwave spectroscopy, 6, 751 photochemical chlorination, 6, 769 synthesis, 6, 780 Ethylene oxide as pharmaceutical, 1, 157 thiophene synthesis from, 4, 899 Ethylene sulfate — see 2,2-dioxide under 1,3,2-Dioxathiolane... 

Pyridine, 2,6-di(2-pyridyl)thiomethyl-synthesis, 2, 435 Pyridine, 2-ethoxy-iV-oxide... 

Pyridinium chloride, N-(4-pyridyl)-hydrochloride quaternization, 2, 175 reactions with amines, 2, 241 Pyridinium chlorochromates as oxidizing agents, 2, 170 reactions, 2, 34 Pyridinium dichromate as oxidizing agent, 2, 170 Pyridinium l-dicyanomethylide... 

S-2-PicoIyl A-Oxide Thioether RSCH2-2-pyridyl N-Oxide (Chart 7)... 

This group has also developed two ring-contraction systems of potential use in crown synthesis. In the first of these, extrusion of a phenylphosphine oxide unit results from treatment with alkoxide ion. In the second, similar conditions initiated decarbonyla-tion of a bis-pyridyl ketone Despite the apparent potential of these methods for crown synthesis, direct formation of crowns by processes which involve them do not appear to have enjoyed great success thus far. 

While pyridine and quinoline N-oxides do not react directly with enamines, they have been found to form a-pyridyl and 2-quinolinyl-2 -cyclohexanones in good yields after prior acylation (371,372). 

In the other extreme, ethyl 3-oxohexanoate 75 required fusion with 3-pyridyl-hydrazide 73a or 3-hydrazinocarbonyl-pyridine-l-oxide 73b at 120°C in order to give the corresponding pyrazol-3-ones 76a,b (92AF1350) (Scheme 22). Depending on the reaction conditions, the reaction of ethyl 3-oxo-3-phenylpropanoate 77 and cyanomethylhydrazide 78 gave different products. Thus, fusion at 140°C gave pyrazol-3-one 79 and N,A -bis(cyanoacetyl)hydrazine 80, while heating in ethanol... 

A variety of silver(I) carbenes can be prepared by interaction of a series of imidazolium salts with silver(I) oxide or silver(I) carbonate (OOJCS(D) 4499). With 3-tert-butyl-l-(2 -pyridylmethyl)imidazolium bromide hydrate and 3-(2", 6"-di-Ao-propylphenyl)-l-(2 -pyridylmethyl)imidazolium bromide hydrate, complexes 85 (R = t-Bu, 2",6"-/-Pr2CgH3) result. 3-(2",4",6"-Trimethylphenyl)-l-(2 -pyridylmethyl)imidazolium bromide in turn leads to 86 (R= 2",4",6"-MejCgH2). 3-(2",6"-Di-wo-propylphenyl)-l-(2 -pyridyl)... 

Cyclization of 3-cyano-2-[(3-hydroxypropyl)amino]-5-(4-pyridyl)pyri-dine-l -oxide (298) in POCI3 yielded 9-cyano-7-(4-pyridyl)-3,4-dihydro-2/f-pyrido[],2-n]-pyrimidine I -oxide (299) (94EJM175). After heating 3-cyano-4-trifluoromethyl-6-phenyl-2-[(3-hydroxypropyl- and 3-hydroxybutyl)-amino] pyridines in boiling POCI3 for 1 h, the product was treated with aqueous NH4OH to yield 6-phenyl-8-trifluoromethyl-9-cyano-3,4-dihydro-2//-pyr-ido-[l,2-n]pyrimidine and its 4-methyl derivative (01CHE329). 

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