P- Aminobenzophenone

Antidepressant activity is retained when the two carbon bridge in imipramine is replaced by a larger, more complex, function. Nucleophilic aromatic substitution on chloropyridine 31 by means of p-aminobenzophenone (32) gives the bicyclic intermediate 33. Reduction of the nitro group (34), followed by intramolecular Schiff base formation gives the required heterocyclic ring system 35. Alkylation of the anion from 35 with l-dimethylamino-3-chloropropane leads to tampramine 36 [8]. 

In acidic media p-aminobenzophenone undergoes ready photoreaction... 

Another perturbing influence is introduced by major solvent changes. Cohen has shown that in acidic media p-aminobenzophenone undergoes ready photoreduction with 2-propanol.378 This effect is readily understood since no charge transfer is possible in the protonated ketone, so no such stabilization of a it,it triplet can occur. 

Phthalyl-p-aminobenzophenone.—This compound, by reduction in sulphuric-acid solution, gives a poor yield of pinacone. 

AMINOBENZOL-SULFONAMIDO)-2,4-DIMETHYLPYRIMIDIN (GERMAN) see SNJOOO (p-AMINOBENZOLSULFONYL)-2-AMINO-4,6-DIMETHYLPYRIMIDIN (GERMAN) see SNJOOO (p-AMINOBENZOLSULFONYL)-2-AMINO-4-METHYLPYRIMIDIN (GERMAN) see ALF250 p-AMINOBENZOPHENONE see AIR250... 

Two types of aromatic carbonyl compound give rise to lowest energy excited states not having (n, ti ) character. Amino substituted benzo-phenonra, especially, para-sul tituted compounds, form excited states which are neither (n, n ) nor (n, n ) in character, but which are better described as charge transfer states. A typical case is provided by p-aminobenzophenone whidi yields an excited state structure as shown ... 

The Ti species abstracts hydrogen from the alcohol (p. 347), and then dimerizes. The /PrO radical, which is formed by this process, donates H to another molecule of ground-state benzophenone, producing acetone and another molecule of 51. This mechanism predicts that the quantum yield for the disappearance of benzophenone should be 2, since each quantum of light results in the conversion of 2 equivalents of benzophenone to 51. Under favorable experimental conditions, the observed quantum yield does approach 2. Benzophenone abstracts hydrogen with very high efficiency. Other aromatic ketones are dimerized with lower quantum yields, and some (e.g., p-aminobenzophenone, o-methylacetophenone) cannot be dimerized at all in 2-propanol (although p-aminobenzophenone, e.g., can be dimerized in cyclohexane ). The reaction has also been carried out electrochemically. 

Indole is acetylated at position 3 by acetic anhydride without a catalyst when vinyl acetate is used as reaction medium.557 Heating benzanilide and benzoic anhydride with polyphosphoric acid for 3 hours at 150° leads, after hydrolysis, to an 84% yield of p-aminobenzophenone.558 Trifluoroacetylation of azulenes has been reported by Anderson and Anderson.559... 

Preparation by diazotization of p-aminobenzophenone, followed by hydrolysis of the diazoninm salt obtained [6,61,122,142], (54%) [15]. 

Methyl-2-aminobenzophenone can be prepared similarly by substituting toluene for benzene. The yield of crude material, m.p. 85-88°, is 70%. On recrystallization from 95% ethanol, using 5 ml. per g., there is obtained, in two crops, a 70% recovery of 4/-methyl-2-aminobenzophenone, m.p. 92-93°. Because of the higher temperature required in the steam distillation (cf. Note 5), the sulfonamide is obtained in a form difficult to purify. As a result the crude aminoketone usually contains 1-2 g. of aluminum oxide. 

A one-step synthesis of ( )-rutacridone (37) was achieved by the reaction of acridone (32 R = H) with isoprene dibromide isorutacridone (36), the isomer with linear annelation, was a minor product of the reaction (Scheme 5).19 A full account of the synthesis of acronycine from o-aminobenzophenones has now appeared (c/. Vol. 7, p. 90) and a modified route has been described (Scheme 6).20 Cyclization of the benzophenone derivative (38 R = Me) gave acronycine (39) (38%) and isoacronycine (40) (38%) a similar ring-closure of compound (38 R = H) furnished des-iV-methylacronycine. 

Sulfonamides. In the first step of a synthesis of 2-aminobenzophenone Scheifele and De Tar converted anthranilic acid into p-toluenesuffonylanthranilic acid using sodium carbonate as base if sodium hydroxide is used the main product is the tosic... 

Aluminum amalgam, 7, 275 Aluminum bromide, 7 Aluminum chloride, 6, 7-9, 49, 295, 299 Aluminum hydride, 9-10, 46 Aluminum isopropoxide, 10 Amalgamated aluminum, 7 Amalgamated magnesium, 7 Amidation, 17 Amides, 23, 147, 277 1-Aminoadamantanes, 295 (3-Amino alcohols, 162 p-Aminobenzaldehyde, 272 2,2 -Aminobenzophenones, 166... 

The base-catalyzed reaction of benzyl cyanides with p-chloronitro-benzenes is widely used as a preparative route to 3-arylanthranils (Eq. 8), and hence, by reductive ring opening, o-aminobenzophenones, the valuable precursors of the pharmacologically important benzodiazepinones. By this method 3-phenylanthranils bearing trifluoromethoxy,173 (trifluoromethyl)-thio,173 sulfonamido,174 methoxy- and ethoxycarbonyl,175,176 cyano,175 methylsulfonyl,175 halo,176 difluoromethoxy,177 and acetyl (protected as the... 

The reduction of anthranils is a particularly valuable route to 5-chloro-2-aminobenzophenones, the precursors of benzodiazepinones of the Valium and Librium type. Reductions are successful with ferrous sulfate,209 zinc,190 or iron181 in hydrochloric acid iron in acetic acid1 54,155,175-177 zinc and calcium chloride in boiling ethanol165 and hydrazine hydrate in warm ethanol.154 Phenylhydrazine reduces anthranils of type 134 to diamino-p-benzoquinones, e.g., 133.195... 

Photolysis of 3,5-diphenylanthranil in concentrated hydrochloric acid produces 5-(p-chlorophenyl)-2-aminobenzophenone as expected from a consideration of mesomeric structures (165 R1 = Ph).228 5-Halogeno-3-phenylanthranils under similar conditions yield 3,5-dihalogeno-2-amino-benzophenones, whereas photolysis in concentrated sulfuric acid results in substitution (by hydroxy) and migration of the halogen to give 2-amino-6-halogeno-5-hydroxybenzophenones in 25-35% yield. Irradiation of 3-phenylanthranils in hydrobromic acid is somewhat different in that unsubstituted o-aminobenzophenones are produced in addition to their bromo derivatives.228... 

---