A One-Step Synthesis of 2-(2-Pyridyl)-3H-indol-3-one N-Oxide:  Is It an Efficient Spin Trap for Hydroxyl Radical?

Unexpected reactions of 4-amino-2-methylsulfonyl-5-nitro-6-phenylethynylpyrimidine with nucleophiles

“…The reaction mixture was kept at room temperature for 2 h. The solvent was evaporated under reduced pressure, the residue was recrystallized from 2-propanol to give compounds 4, 5 or 6. (4). Yield 85%; mp 155-157°C.…”

“…The latter compounds, being aza-analogues of isatogens, attracted our attention as potential traps for free radicals in biological milieu [3][4][5]. In continuing our research aimed on the synthesis of polysubstituted pyrrolo-[3,2-d]pyrimidine 5-oxides via cyclization of 6-arylethynyl-5-nitropyrimidines, we decided to perform modification of the 2-position of the starting 6-arylethynyl-5-nitropyrimidines based on oxidation of methylthio moiety followed by nucleophilic substitution reaction.…”

Preparation of N-aryl-ketonitrone spin traps

“…On the other hand, a survey of the literature data shows that only a few cyclic ketonitrones have been used in spin trapping experiments [16][17][18][19][20][21][22][23], while no linear nitrone has ever been employed as spin trapping agent. This is all the more remarkable since many aldonitrones, derived from either 5,5-dimethyl-3,4-dihydro-2H-pyrrole N -oxide (DMPO) or (Z)-benzylidene(tert-butyl)azane oxide (PBN) have been widely used to detect free radicals in every kind of media [1][2][3][4][5][24][25][26].…”

“…This is partly due to the difficulty encountered in the preparation of these compounds, most of the methods commonly used to prepare aldonitrones being not transposable to the synthesis of ketonitrones [7][8][9][10][11][12][13][14]27]. In addition, when ketonitrones are used as spin trapping agents, the identification of the addend from the adduct EPR spectra is less easy than in the case of spin adducts of aldonitrones, because of the lack of hyperfine coupling between the unpaired electron and a hydrogen nucleus in the β-position towards the nitrogen [5,[16][17][18][19][20][21][22][23]. Note however that the combination of separation techniques and other analytical methods, such as HPLC and mass spectrometry, with spin trapping could provide additional information on the structure of the radical trapped [28][29][30], which should generate a renewal of interest for ketonitrone spin traps.…”

Synthesis of 2,4‐disubstituted 6‐phenyl‐7H‐pyrrolo[3,2‐d]‐pyrimidin‐7‐one 5‐oxides

“…Pyrrolo[3,2-d]pyrimidin-7-one 5-oxides, being azaanalogues of isatogens, attract our attention as potential free radical traps in biological milieu [1][2][3]. Moreover, the pyrrolo [3,2-d]pyrimidine heterosystem is an important class of compounds, possessing notable biological activities, in particular purine nucleoside phosphorylase [4,5] and thymidylate synthase [6,7] inhibitory, neuropeptide Y5 receptor [8] and A 1 ,A 2 -adenoside receptor [9] antagonistic properties.…”