Indolizines, 2-phenyl-, nitration

Indolizine, hydroxy-conformations, 4, 451 GLC retention times, 4, 451 synthesis, 4, 121 tautomerism, 4, 198, 452 Indolizine, 2-hydroxy-synthesis, 4, 463 Indolizine, 8-hydroxy-conformation, 4, 452 Indolizine, 2-hydroxymethyl-synthesis, 4, 461 Indolizine, 3-hydroxymethyl-synthesis, 4, 461 Indolizine, 6-hydroxymethyl-synthesis, 4, 461 Indolizine, methyl-mass spectra, 4, 187, 450 NM 4, 448 Indolizine, 2-methyl-diazo coupling, 4, 454 mass spectra, 2, 529, 4, 450 nitration, 4, 50, 454 nitrosation, 4, 454 reaction with diaryl disulfide, 4, 460 reaction with nitroethane, 4, 460 Indolizine, 3-methyl-basicity, 4, 454 Indolizine, 5-methyl-acidity, 4, 461 synthesis, 4, 466 Indolizine, 6-methyl-mass spectra, 4, 450 Indolizine, l-methyl-2-phenyl-nitration, 4, 454 nitrosation, 4, 454, 455 Indolizine, 3-methyl-2-phenyl-reaction... 

Nitration of indolizines often runs the risk of oxidation. The orientation of the substitution appears to depend on the experimental conditions nitration of 2-methylindolizine in a mixture of nitric acid and sulfuric acid occurs at the 1 -position (46JCS1075) in acetic anhydride at -70 °C, on the other hand, 2-methyl-3-nitroindolizine is formed (72JCS(P1)2954). The nitration of 2-phenylindolizine with nitric acid in aqueous sulfuric acid gave 2-(4-nitro-phenyl)indolizine (32a) and l-nitro-2-(4-nitrophenyl) indolizine (32b) together with 20% of an unidentified dinitro compound, possibly 3-nitro-2-(4-nitrophenyl)indolizine (32c) <79JCS(P2)312>. 

Nitration of indolizines is seldom attempted in view of accompanying oxidation reactions. Thus the synthesis of 6- and 8-nitro-2-phenyl-indolizine has been achieved by the cyclization of appropriately substituted 2-methyl-1-phenacylpyridinium bromide.179 However, 1-nitro and 1,3-dinitro compounds have been prepared.4 From the behavior of the indolizine nucleus toward other electrophiles, 3-nitroindolizine might be expected to be the primary product. This compound has been synthesized using a dilute solution of nitric acid in acetic acid at - 70°C where the substrate could well be the base and not the 3-protonated cation as in a nitric acid-sulfuric acid mixture.180... 

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