A-Nitroacetophenones

Aldehydes react with a-nitroacetophenone in refluxing toluene to generate a 3-acetyl-2-isoxazoline (78USP4092327), while a-nitroacetophenone oxides react with alkenes to provide 2-isoxazolines (Scheme 121) (79ZOR735, 79ZOR2408, 80CPB479>. 

The use of dinitrogen pentoxide in the Ponzio reaction for the oxidation-iutration of oximes to em-dinitro groups has been reported by Russian chemists. Millar and co-workers extensively investigated these reactions and reported the synthesis of 2,4,5,7,9,9-hexanitrofluorene (2), a thermally stable explosive with an oxygen balance better than TNT. Other energetic materials containing gem-dinitro functionality were synthesized from the oximes of acetophenone, 4-nitroacetophenone, a-nitroacetophenone and 2-hydroxyacetophenone. 

The addition to alkenes of radicals derived from an a-nitroketone is also catalysed by manganese(III) [30]. During the reaction between a-nitroacetophenone 8 and m-but-2-ene, the stereochemical relationship between the methyl substituents is not preserved. The process terminates with the formation of a nitrone. A related process will generate nitromethyl radicals from nitromethane and these add to benzene to give phenyinitromethane [31],... 

Condensation of a-bromo-a-nitroacetophenone with JV-arylselenoureas has given 5-nitroselenazoles (73) [Eq. (23)].64... 

Nitro alcohols from the condensation of aromatic aldehydes with sodium salts of nitroparaffins are oxidized to a-nitro ketones with chromic-acetic acids, as illustrated by the preparation of a-nitroacetophenone, CjHsCOCHjNOj (80%). ... 

The Ni(acac)2/MAO/Et3N system produces partially isotactic polystyrene with moderate molecular weight (Mw = 9,000-25,000 Mw/A/n = 1.6-4.2 75-85% m diads). Ni(a-naph)2 (a-naph = a-nitroacetophenonate. Figure 14.21, 101) and Ni(hfacac)2 (hfacac = hexafluoroacetylacetonate. Figure 14.21, 102) in combination with MAO and PCys as an ancillary ligand (PCys ligates in situ Cy = cyclohexyl) can also catalyze the polymerization of styrene to produce partially isotactic... 

Formic acid is a good reducing agent in the presence of Pd on carbon as a catalyst. Aromatic nitro compounds are reduced to aniline with formic acid[100]. Selective reduction of one nitro group in 2,4-dinitrotoluene (112) with triethylammonium formate is possible[101]. o-Nitroacetophenone (113) is first reduced to o-aminoacetophenone, then to o-ethylaniline when an excess of formate is used[102]. Ammonium and potassium formate are also used for the reduction of aliphatic and aromatic nitro compounds. Pd on carbon is a good catalyst[103,104]. NaBH4 is also used for the Pd-catalyzed reduction of nitro compounds 105]. However, the ,/)-unsaturated nitroalkene 114 is partially reduced to the oxime 115 with ammonium formate[106]... 

The catalyst used throughout this study was a 1% w/w palladium on graphite powder (S.A. 10 mV ) supplied by Johnson Matthey. 2-nitroacetophenone, 3-nitroacetophenone and 4-nitroacetophenone (all Aldrich >99 %) were used without further purification. No significant impurities were detected by GC. Gases (BOG, >99.99 %) were used as received. 

The hydrogenation of nitroacetophenones has been studied and considerable kinetic and mechanistic information obtained. Differences in reaction rate, bonding and selectivity have been observed. The formation of 1-indolinone from 2-NAP was unexpected and revealed the presence of a surface nitrene. This intermediate has not been postulated in nitroaromatic hydrogenation previously. Hydrogenation in the presence of deuterium revealed, as well as a kinetic isotope effect, that it is likely that... 

CINNOLINES AND QUINOXALINES Replacement of a methine in oxolinic acid (46) by nitrogen is apparently consistent with retention of antibacterial activity. One approach begins with reduction of nitroacetophenone 144 to afford the corresponding aminoketone (145). Treatment of this intermediate with nitrous acid leads to the diazonium salt the diazonium group condenses with the ketone methylene group (as its enol form) to lead to the cyclized product, cinnoline 147. Bromination proceeds at the position adjacent the enol grouping (148) ... 

Although 550 suffices to dissolve the w-nitroacetophenone it is desirable to bring the alcoholic solution to a boil to avoid crystallization during filtration. 

The photoreduction of aromatic nitro compounds to the amino compounds can be carried out on the surface of semiconductor particles such as titanium oxide1 with H-atom donors (equation 1). At a shorter duration of the photoinduced reduction of p-nitroacetophenone, the hydroxylamine intermediate can be obtained in about 30% yield. The reaction mechanism proposed is based on the photoexcitation of TiC>2 to generate an electron and a positive hole (equations 2 and 3). Aliphatic nitro compounds such as 12-nitrododecanoic acid can be reduced to 12-amino dodecanoic acid in 90% yield by this method. 

Preferential reduction of a nitro group in the presence of a carbonyl group in 4-nitroacetophenone ISD, intramolecular rearrangements of o-nitro-benzanilides 32) intramolecular cyclizations of o-nitro-ferf-anilines to benzimidazol-1-oxides 153,154) cyclizations of acylated 2-nitrodiphenylamines to phenazine-l-oxides i ), intramolecular additions of nitro groups to double bonds 156) remarkably ef-... 

A variety of aliphatic and aromatic ketones have been investigated (cyclohexanone, cyclopentanone, acetophenone, p-nitroacetophenone) and they all usually lead to 2-R -3-R"-5-nitropyridine in moderate to good yields. Better yields were recorded when enamines of the respective ketones were used. With aldehydes the yields are in general lower than with ketones. 

R = H), and 4-p-nitrophenylpyrimidine (123, R = NO2) by reaction with cyclopentanone, acetophenone, and / -nitroacetophenone, respectively. The yields are, however, quite low (15-30%) and the reaction is found to be applicable to restricted substrates. In some of these reactions A -methyl-a-nitroacetamide could be isolated as the other reaction product. 

The reduction of a dinitro ketone to an azo ketone is best achieved with glucose. 2,2 -Dinitrobenzophenone treated with glucose in methanolic sodium hydroxide at 60° afforded 82% of dibenzo[c,f [i 2]diazepin-l 1-one whereas lithium aluminum hydride yielded 24% of bis(o-nitrophenyl)methanol [575], Conversion of aromatic nitro ketones with a nitro group in the ring into amino ketones has been achieved by means of stannous chloride, which reduced 4-chloro-3-nitroacetophenone to 3-amino-4-chloroacetophenone in 91% yield [178]. A more dependable reagent for this purpose proved to be iron which, in acidic medium, reduced m-nitroacetophenone to m-aminoacetophenone in 80% yield and o-nitrobenzophenone to o-aminobenzophenone in 89% yield (stannous chloride was unsuccessful in the latter case) [903]. Iron has also been used for the reduction of o-nitrochalcone, 3-(o-nitrophenyl)-l-phenyl-2-propen-l-one, to 3-(o-aminophenyl)-l-phenyl-2-propen-l-one in 80% yield [555]. 

However, this reaction possibly does not have a general character (e.g., unsubstituted oc-nitroacetophenone does not react under the described conditions). 

The CCH of p-nitroacetophenone (5) (Scheme 2) was inefficient and unselective giving p-aminoacetophenone (6) in about 20% yield together with some 10-12% of unindentified compounds (30% mass balance). Attempts to recover more material were unsuccessful. The ECH at a RCu cathode in an alkaline (0.28 M KOH, pH 13.5) MeOH-HzO (1.5% of H2O) solution was reported to give exclusively p-amino-acetophenone (6) (79% yield of isolated product) (3,8). 

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