M-Nitrobenzophenone

Obtained by electrolytic reduction of m-nitrobenzophenone in concentrated sulfuric acid for 30 h, followed by action of hydrochloric acid gas in ethyl ether on the amino ketone so obtained [567]. 

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]. 

Also obtained from 4-bromo-3-nitrobenzophenone (m.p. 124°) by heating with a mixture of sodium acetate and acetamide at 175-200° for 2 h (good yield) [549],... 

Preparation by saponification of 2-(benzoyloxy)-6-bromo-5-methoxy-4-nitrobenzophenone (SM) with potassium hydroxide in ethanol (71%). SM was obtained by oxidation of 4-bromo-5-methoxy-6-nitro-2,3-diphenylbenzofuran with chromium Irioxide in boiling acetic acid for 30 min [571]. Also obtained by hydrolysis of 6-bromo-5-methoxy-4-nitro-2-(4-nitrobenzoy-loxy)benzophenone [571], m.p. 126° [571] Spectra (NA). 

Preparation by Friedel-Crafts acylation of bromobenzene with m-nitrobenzoyl chloride, reduction of the obtained 4-bromo-3 -nitrobenzophenone and diazotization of the resulting 3-amino-4 -bromobenzophenone, followed by hydrolysis of the diazonium salt [900]. 

Preparation by diazotization of 3-amino-4 -chlorobenzo-phenone (SM), followed by hydrolysis of the diazonium salt obtained (81%) [900], (84%) [634]. SM was obtained by Friedel-Crafls acylation of chlorobenzene with m-nitro-benzoyl chloride, followed by reduction of the resulting 4-chloro-3 -nitrobenzophenone [900]. 

Also obtained by reaction of m-nitrobenzoyl chloride with anisole in the presence of aluminium chloride in refluxing carbon disulfide for 2 h (16%) [959], In this reaction, 4-methoxy-3 -nitrobenzophenone was the major product. 

Preparation by acylation of phenetole with m-nitrobenzoyl chloride in ethyl ether in the presence of alumininm chloride, then dealkylation of the 4-ethoxy-3 -nitrobenzophenone so formed with the same catalyst [141], in boiling carbon disulfide (60-70°) for 8 h [619] according to [139]. Preparation by Fries rearrangement of phenyl m-nitrobenzoate with alumininm chloride [897] without solvent at 120° or at 160° for 2 h (32%) [958]. 

Preparation by demethylation of 2-chloro-2 -methoxy-5 -methyl-4-nitrobenzophenone with excess boiling pyridinium chloride for 30 min (57%) [1073], m.p. 130° [1073] Spectra (NA). 

Also obtained by reduction of 2-methoxy-5-methyl-4 -nitrobenzophenone (m.p. 101-102°) [683],... 

Preparation by demethylation of 3,4 -dime-thoxy-4-hydroxy-5-nitrobenzophenone with hydrobromic acid in refluxing acetic add [1019]. m.p. 212-214° [1019] Spectra (NA). 

Also obtained by reaction of dimethyl sulfate with 5-chloro-2-hydroxy-4 -nitrobenzophenone in the presence of aqueous sodium hydroxide [1684], b.p.jj 265° [1585] m.p. 114° [1684, 1585]. 

Fin 1989 Findeis, M.A. and Kaiser, E.T., Nitrobenzophenone Oxime Based Resins for the Solid-Phase Synthesis of Protected Peptide Segments, J. Org. Chem., 54 (1989) 3478-3482. 

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