Benzophenone derivatives

Nitrobenzotrichloride is also obtained in high yield with no significant hydrolysis when nitration with a mixture of nitric and sulfuric acids is carried out below 30°C (31). 2,4-Dihydroxybenzophenone [131 -56-6] is formed in 90% yield by the uncatalyzed reaction of benzotrichloride with resorcinol in hydroxyHc solvents (32) or in benzene containing methanol or ethanol (33). Benzophenone derivatives are formed from a variety of aromatic compounds by reaction with benzotrichloride in aqueous or alcohoHc hydrofluoric acid (34). 

Since acetal resins are degraded by ultra violet light, additives may be included to improve the resistance of the polymer. Carbon black is effective but as in the case of polyethylene it must be well dispersed in the polymer. The finer the particle size the better the ultra violet stability of the polymer but the poorer the heat stability. About 1.5% is generally recommended. For white compounds and those with pastel colours titanium dioxide is as good in polyacetals as most transparent ultraviolet absorbers, such as the benzophenone derivatives and other materials discussed in Chapter 7. Such ultraviolet absorbers may be used for compounds that are neither black, white nor pastel shade in colour. 

The efficiency of reduction of benzophenone derivatives is greatly diminished when an ortho alkyl substituent is present because a new photoreaction, intramolecular hydrogen-atom abstraction, then becomes the dominant process. The abstraction takes place from the benzylic position on the adjacent alkyl chain, giving an unstable enol that can revert to the original benzophenone without photoreduction. This process is known as photoenolization Photoenolization can be detected, even though no net transformation of the reactant occurs, by photolysis in deuterated hydroxylic solvents. The proton of the enolic hydroxyl is rapidly exchanged with solvent, so deuterium is introduced at the benzylic position. Deuterium is also introduced if the enol is protonated at the benzylic carbon by solvent ... 

Ultraviolet absorptions ofvinylogous lactams were found by MOLCAO calculations and compared with experimental values (663). Infrared spectroscopic studies of vinylogous amides (664) and some fifty vinylogous urethanes (665) allowed configurational and structural assignments. The effect of enamine-imine equilibrium in a series of benzophenone derivatives was established (666) and the effect of structure on enamine basicity studied (667). 

Chloro-5-nitrobenzaldehyde, -acetophenone, or -benzophenone derivatives treated with 2-aminothiophenol under alkaline conditions provided good yields of the corresponding dibenzo[(3,/][l,4]thiepins. Similar treatment of 2-chloro-3,5-dinitrobenzophenone (318) provided 58% of dibenzo[(3,/][l,4]thiepin 321 and 20% of phenothiazine 323. Its formation can be easily explain by the Smiles rearrangement of the initially formed intermediate 320 into diphenylamine derivative 322, followed by denitrocyclization reaction leading to the corresponding product of denitrocyclization 323 (Scheme 49). When the reaction was done in pyridine, only this product was isolated in 50% yield (57JCS3818). 

El fazepam (80) not only is a tranquilizer, but also stimulates feeding in satiated animals. One of several syntheses involves reaction of benzophenone derivative with a glycine equivalent masked as an oxazolidine-2,5-dione (79). ... 

Photo-induced grafting onto wood cellulose with several vinyl monomers using phenyl acetophenone and benzophenone derivatives as photosensitizers has been reported [72]. A fast increase in grafting was observed for short irradiation times, whereas longer ones resulted in a decreased percent grafting. 

The benzophenone derivative 18 (0.100 g. 0.311 mmol) in MeCN (6mL) was treated with Nal (0.047 g, 0.311 mmol) and (NH4)2C03 (0.400 g, large excess) and the mixture was stirred at 20 C for 24 h and then filtered. The solid was washed with CH2C12 the combined filtrate and washings were washed with H,0, dried and evaporated in vacuo. Chromatography of the residue (16% EtOAc/CH,Cl,) gave 19a yield. 0.80 g (90%). 

Phenylbenzisothiazolescan be photochemically transformed to benzophenone derivatives however. depending on the solvent, 1,5-diazocine systems, generated by dimerization of the primarily formed product, can be isolated.36... 

Titanium(III) chloride (particularly in slightly alkaline medium) reduces the p-nitro groups of the thiophosphate insecticides to amino groups, which are then reacted with nitrite in acid mediiun in a second step to yield a diazonium compound as intermediate. This is then coupled to N-(l-naphthyl)-ethylenediamine dihydrochloride to yield an azo dye [3]. In the case of benzodiazepines the first reaction step includes an additional acid hydrolysis to the corresponding benzophenone derivative [2]. 

Hydroxyacetophenone [23] and benzophenone derivatives [24] N-containing glycolate esters [25]... 

Benzo(b)fIuoranthrene la 39, 85 Benzo(k)fluoranthrene la 39, 86 Benzo(ghi)perylene la 39,85 Benzophenone derivatives lb 282 Benzo(a)pyrene la 39,85,103 p-Benzoquinone derivatives la 72 Benzothiazoles lb 237 Benzoyl chloride la 70 Benzoylecgonine lb 32,34,35 3,4-Benzpyrene la 60 Benzthiazide lb 188 Benztriazole, 2-(2-hydroxy-5-methyl-phe-nyl)- la 282... 

Figure 7.39 Structural assignments of a benzophenone derivative based on low- and high-resolution mass spectrometry. After Squirrell [258], From D.C.M. Squirrell, Analyst, 106, 1042-1056 (1981). Reproduced by permission of The Royal Society of Chemistry...

To obtain more information on this point, let us examine the data given in Table 3.6<42-47> for some substituted benzophenones. The data in Table 3.6 indicate that benzophenone derivatives having lowest triplet states of n->TT character undergo very efficient photoreduction in isopropyl alcohol. Those derivatives having a lowest it- -it triplet, on the other hand, are only poorly photoreduced, while those having lowest triplets of the charge-transfer type are the least reactive toward photoreduction. In additon, in some cases photoreduction is more efficient in the nonpolar solvent cyclohexane than in isopropanol. This arises from the solvent effect on the transition energies for -> , ir- , and CT transitions discussed in Chapter 1 (see also Table 3.7). 

As part of their study of enzyme models capable of remote oxidation, Breslow and co-workers have used a benzophenone derivative to function-... 

Benzophenones are distributed scarcely in foods. They are mainly present in the Garcinia genus, such as in fruits of Garcinia indica (Yamaguchi and others 2000) and Garcinia cambogia (Masullo and others 2008), characteristic products of India. Recently, benzophenone derivatives have also been identified in several by-products of mango at low concentrations (0-15 mg/100 g FW) (Barreto and others 2008). 

Berardini N, Carle R and Schieber A. 2004. Characterization of gallotannins and benzophenone derivatives from mango (Mangifera indica L. cv. Tommy Atkins ) peels, pulp and kernels by high-performance liquid chromatography/electrospray ionization mass spectrometry. Rapid Commun Mass Spectrom 18(19) 2208—2216. 

GTP-bound a-subunit activates a cGMP-specific phosphodiesterase as described briefly earlier. A benzophenone derivative of cGMP was prepared and found to inhibit several types of cyclic nucleotide phosphodiesterases at low concentrations. In rod outer segment preparations, the [a-32P]-tagged probe... 

Treatment of the propargylic alcohol 144, readily prepared from condensation between benzophenone (143) and the lithium acetylide 101, with thionyl chloride promoted a sequence of reactions with an initial formation of the chlorosulfite 145 followed by an SNi reaction to produce in situ the chlorinated and the benzannulated enyne-allene 146 (Scheme 20.30) [62], A spontaneous Schmittel cyclization then generated the biradical 147, which in turn underwent a radical-radical coupling to form the formal [4+ 2]-cycloaddition product 148 and subsequently, after a prototropic rearrangement, 149. The chloride 149 is prone to hydrolysis to give the corresponding 11 H-bcnzo h fluoren-ll-ol 150 in 85% overall yield from 144. Several other llff-benzo[fc]fluoren-ll-ols were likewise synthesized from benzophenone derivatives. 

Several researchers have investigated the photoenolization of various o-methyl acetophenone and o-methyl benzophenone derivatives. The mechanism of photoenolization of o-methyl benzophenone, 1, has been studied with laser flash photolysis and can be described as follows (Scheme 2) Irradiating 1 forms its first... 

The interaction of aliphatic a,o)-dicarboxylates and open-chain benzophenone derivatives containing carboxyl or ammonium groups have been described Breslow R, Rajagopalan R, Schwarz J (1981) J Am Chem Soc 103 2905... 

H2N.C6H3(N02)2C0.C6H3(N02)2-NH2 mw 302 24, N 18.54% crysts (from abs ale), red ndls becoming yel on heating, red ndls (from pyridine), mp 289-93° almost insol in all org solvs, except pyridine was prepd by reaction of ale NH3 with 3,3I dinicro-4,4 -dichlorobenzophenone at 150° or in the presence of Na acetate at 125° and by reaction of ale NHj on the dibramo or di-iodo-dinitro-benzophenone deriv at 150°. Its expl props are not reported... 

Synthesis of Protected Amino Acids Containing Benzophenone Derivatives... 

The crude solid was suspended in benzene/hexanes (1 1, 100 mL), heated, and decanted after cooling. The supernatant was applied to a column of silica gel G (70 g, benzene/hexanes 1 1) to separate the benzophenone derivative from the phenyl benzoate contaminant. The column was eluted with the same solvent (250 mL), followed by benzene/hexanes (3 1, 350 mL), and finally with benzene. Fractions (50 mL) were collected. Fractions containing the component with Rf 0.14 (silica gel, benzene) were pooled and concentrated on a rotary evaporator. Recrystallization (abs EtOH) of the residue [2.4 g (15% based on starting phenol)] gave colorless needles of 94 yield 2.2 g (14%) mp 137-138°C. 

Several types of imine have been used as protective groups for amines in solution [230]. Most are stable towards bases, but can be hydrolyzed by acids. Benzophenone-derived imines can be prepared by treating support-bound aliphatic primary amines with benzophenone imine [148,260], but usually not by treatment with benzophenone. Polystyrene-bound benzophenone imines of glycine are sufficiently C,H-acidic to enable C-alkylation with alkyl halides [260,313] or Michael acceptors [314], and have mainly been used for this purpose (see Section 13.4.4). 

As the pharmacokinetic properties of the azomethine prodrugs of (7 )-a-methyl-histamine (12) were found to strikingly depend on their physico-chemical properties, it was attempted to quantify the relationship between lipophilicity and CNS penetration of the benzophenone derived imines [50], The main obstacle to the experimental measurement of the azomethines log P values was the competing hydrolysis of the... 

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