Benzophenones, reactions with

The condensation of aldehydes and ketones with succinic esters in the presence of sodium ethoxide is known as the Stobbe condensation. The reaction with sodium ethoxide is comparatively slow and a httlo reduction of the ketonic compound to the carbinol usually occurs a shorter reaction time and a better yield is generally obtained with the more powerful condensing agent potassium ieri.-butoxide or with sodium hydride. Thus benzophenone condenses with diethyl succinate in the presence of potassium [Pg.919]

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). 

A-Substituted pyrroles, furans and dialkylthiophenes undergo photosensitized [2 + 2] cycloaddition reactions with carbonyl compounds to give oxetanes. This is illustrated by the addition of furan and benzophenone to give the oxetane (138). The photochemical reaction of pyrroles with aliphatic aldehydes and ketones results in the regiospecific formation of 3-(l-hydroxyalkyl)pyrroles (e.g. 139). The intermediate oxetane undergoes rearrangement under the reaction conditions (79JOC2949). 

The derivative of glycine, prepared from benzophenone (cat. BF3 Et20, xylene, reflux, 82% yield), has found considerable use in the preparation of amino acids. It can also be prepared by an exchange reaction with benzophenoneimine (Ph2C=NH, CH2CI2, rt). ... 

An ingenious synthesis of 1-arylisoindolcs has been developed by Vebor and Lwowski, based upon the reaction of an o-phthalimido-methylbenzophenone (41, R = aryl) with hydrazine (Table IV). The benzophenone is prepared by a Friedel-Crafts reaction with o-phthalimidomethylbenzoyl chloride (40). The mechanism of isoindole formation can be represented sehematically by a sequence involving attack by hydrazine at the imide to give the ring-opened hj drazide (42), followed by cyclization to phthalazine-l,4-dione (44) with displacement of the o-aminomethylbenzophenone (43). Intramolecular condensation of the latter can lead, via the isoindolenine... 

The actual mechanism by which a particular reaction proceeds strongly depends on the nature of the organomagnesium reagent. For instance benzophenone reacts with methylmagnesium bromide by a polar mechanism, while the reaction with t-butylmagnesium chloride proceeds for steric reasons by a SET-mechanism. 

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). ... 

A further variant of Method B is the acylation of a 2-aminobenzophenone with a protected a-amino acid chloride, followed by conversion of the product 11 into the 2-(aminoacet-amido)benzophenone 12 by reaction with hydrobromic acid in acetic acid.196... 

Hexamethylenetetramine can serve as a source of ammonia in the reaction with a 2-(haloacet-amido)benzophenone. The intermediate salts 14, which can be isolated, are readily transformed into benzodiazepinones IS in refluxing ethanol (Method C). Selected examples are given.197 198... 

The achiral molybdenum enolate 2 reacts with benzophenone and benzaldehyde at —78 °C to yield the x,/i-unsaturated molybdenum-acyl complexes34, which presumably arise via elimination of hydroxide from unobserved aldolate intermediates such as 3. No examples of such aldol reactions with complexes that are chiral at molybdenum have been reported. 

Reactions with Benzophenone, l,2-Diphenyl-1,2-diketone, and 3,5-Di-tert-... 

Cycloaddition Reaction with Benzophenone and Thermolysis of the Product... 

The base-stabilized germanimine (Me2Si)2(N-t-Bu)4Ge=N(SiMe3) does not react with benzophenone, even upon heating.72 Apparently, no other reactions between stable germanimines and simple carbonyl compounds have been investigated however, the reaction with a diketone, 3,5-di-r-butyl-ort/io-quinone, has. Both a [2 + 2] and a [2 + 4] cycloaddition reaction have been postulated the initially formed adducts are unstable and decompose (see Scheme 4). 

In Section 3.1 it was shown that the photoreduction of benzophenone can be quenched by addition of small amounts of triplet quenchers such as oxygen or ferric dipivaloylmethide.<60) In fact this was presented as evidence that the benzophenone triplet was involved in the photoreduction. This reaction can also be quenched by naphthalene. In the presence of naphthalene, light is still absorbed by benzophenone and thus benzophenone triplets are produced. However, photoreduction products are decreased. On examining this reaction with flash photolysis, triplet-triplet absorptions were observed but these absorptions corresponded to those of the naphthalene triplet. Thus the triplet excitation energy originally present in the benzophenone triplet must have been transferred to naphthalene and since little of the photoreduction product was observed, this transfer must have been fast in relation... 

This reaction with TMEDA is temperature dependent. When the reaction of U with benzophenone is carried out at 70 °C, TPE is produced exclusively, with no TPA or DPM seen. As the reaction temperature is increased above 70 °C, the amounts of TPA and DPM produced increase. It appears that th hydrogenated products TPA and DPM arise when benzophenone reacts with U containing uranium hydrides. These hydrides may be formed from either substrates containing acidic hydrogens, or by thermal reaction of the low valent uranium species with coordinated TMEDA. 

Figure 2 Double-stranded oligonucleotide photoprobes that simulate modified DNA and intended to cross-link to DNA-binding proteins. (A) Probe modeling interstrand cross-linking by cisplatin Source From Ref. [63], with permission from the American Chemical Society via the Rightslink service (license number 2458870278307 granted June 30, 2010). The benzophenone probe prior to reaction with DNA is shown in the lower part of the panel. (B) Photoaffinity probe for bacterial DNA repair proteins. TT is a simulated thymine dimer intended to be recognized as a site of damage in DNA, and T (two instances) is the diazirine thymine derivative T Source From Ref. [64], with permission from Wiley.

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