Ketone benzyl phenyl ketones

The first application of the time-resolved CIDNP method by Closs and co-workers involved tire Norrish 1 cleavage of benzyl phenyl ketone [24, 25]. Geminate RPs may recombine to regenerate the starting material while escaped RPs may fonn the starting ketone (12), bibenzyl (3), or benzil (4), as shown below. 

Diphenylthiirene 1-oxide reacts with hydroxylamine to give the oxime of benzyl phenyl ketone (79JA390). The reaction probably occurs by addition to the carbon-carbon double bond followed by loss of sulfur monoxide (Scheme 80). Dimethylamine adds to the double bond of 2,3-diphenylthiirene 1,1-dioxide with loss of sulfur dioxide (Scheme 81) (75JOC3189). Azide ion gives seven products, one of which involves cleavage of the carbon-carbon bond of an intermediate cycloadduct (Scheme 81) (80JOC2604). 

Ketones are oxidatively cleaved by Cr(VI) or Mn(VII) reagents. The reaction is sometimes of utility in the synthesis of difunctional molecules by ring cleavage. The mechanism for both reagents is believed to involve an enol intermediate.206 A study involving both kinetic data and quantitative product studies has permitted a fairly complete description of the Cr(VI) oxidation of benzyl phenyl ketone.207 The products include both oxidative-cleavage products and benzil, 7, which results from oxidation a to the carbonyl. In addition, the dimeric product 8, which is suggestive of radical intermediates, is formed under some conditions. 

Nickel prepared by reduction of nickel chloride with sodium borohydride was used for desulfurization of diethyl mercaptole of benzil. Partial desulfurization using 2 mol of nickel per mol of the mercaptole gave 71% yield of ethylthiodesoxybenzoin while treatment with a 10-fold molar excess of nickel over the mercaptole gave 61% yield of desoxybenzoin (benzyl phenyl ketone) 937. ... 

With this method styrene derivatives are oxidized in very good yields (complete conversion at 56 °C after 2-5 hours), whereas aliphatic alkenes require longer reaction time (8-20 h) and increased amounts of oxidant (3.5 eq.), and afford methyl ketones in moderate to good yields. Besides terminal olefins also stilbene and ethyl cinnamate have been converted to benzyl phenyl ketone and /3-ketoester. The catalyst solution can be reused 8 times without decrease in yield. 

Both the nitrosoenamine II and the nitrosamino acetate III demonstrated some unusual chemistry which led us to the study of nitrosamine fragmentation reactions which will be discussed below. Treatment of the nitrosoenamine II with dilute sulfuric acid led to the formation of benzyl phenyl ketone as anticipated, but the major product from this reaction was benzoin, as is illustrated in equation 2 (3). While this transformation and the proper-... 

A polymerization unit containing separate glass ampoules of purified w-hexylisocya-nate, the initiator, and a reaction terminator, was connected to a vacuum and then sealed. The reaction conditions were — 98°C and 1 x 10-6 torr with a reaction time between 5 and 15 minutes. To set the reaction temperature, liquid nitrogen was added to methanol contained in a constant temperature bath to freeze the methanol and the temperature measured using a low-temperature thermometer. The initiator, sodium-benzyl phenyl ketone, was obtained by reacting sodium metal with an equivalent amount of benzyl phenyl ketone in THF and used immediately. The terminator consisted of hydrochloric acid-methanol mixture solution. Reaction scoping results are provided in Table 1. 

TABLE 1. Reaction Scoping for Anionic Polymerization of n-Hexylisocyanate Using Sodium-Benzyl Phenyl Ketone as Initiator... 

Another convenient method for the preparation of functionalized cyclobutanol derivatives is by treatment of 1,2-diphenylethylene acetals containing a 1,3-dithiane moiety in the y-position, e.g. 14c. with butyllithium. The isolation of 2,2-(propane-l,3-diyldisulfanyl)cyclobutanol (15c) together with benzyl phenyl ketone in 90 and 92 % yield, respectively, indicates that the reaction mechanism should involve the intramolecular attack of the metalated dithiane on the acetal carbon atom with concomitant hydride shift at the acetal group.15... 

Exercise 16-44 Strong acid converts 1,1 -diphenyl-1,2-ethanediol first to diphenyl-ethanal and then more slowly to 1,2-diphenylethanone (benzyl phenyl ketone). Explain how and why kinetic and equilibrium control may be expected in this case to give different products. 

Alkyl aryl ketones are known to be arylated at the a-position of the alkyl groups, via the corresponding enolates, by treatment with aryl halides in the presence of palladium catalysts [4, 9]. The ortho arylation of alkyl aryl ketones is also possible. For example, in the reaction of benzyl phenyl ketones with bromobenzenes, the arylation first occurs at the benzylic position the ortho positions are then arylated via C-H bond cleavage (Eq. 8) [15]. The ortho arylation is believed to occur after coordination of the enol oxygen to ArPd(II), which is followed by ortho palladation as in the reaction of 2-phenylphenols shown in Scheme 2. 

The thermal cyclizations of the 2-pyridylhydrazones of cyclohexanone and benzyl phenyl ketone have been effected in good yield.4180 In the absence of the acid catalyst, the pyridine ring is not protonated and is, therefore, more susceptible to electrophilic attack. 

Acetophenones and benzyl phenyl ketones are arylated not only on the a-posi-tion, but also on the two orfho-positions using excess aryl bromides (Eq. 63) [129]. The reaction proceeds via a-arylation (see Sect. 2.2) followed by aromatic arylation. The latter seems to occur via coordination of the enolate oxygen to arylpalladium species, as in the reaction of 2-phenylphenols and 1-naphthols (Eqs. 56-58). Benzanilides are similarly diarylated on the benzoyl moiety using aryl bromides or triflates (Eq. 64) [130]. AT-Arylation [ 131 ] is not observed under the given conditions. 

SYNS BENZYL PHENYL KETONE DEOXYBENZO-IN DESOXYBENZOIN 1,2-DIPHENYLETHANONE 2-PHENYL, CETOPHENONE PHENYL BENZYL KETONE... 

Oxidation of diphenylcyclopropenone with m-chloroperbenzoic acid gave a mixture of benzil, diphenylacetylene and benzophenone, whereas di-r-butylcyclopropenone gave mainly 4,5-epoxy-2,2,4,5-tetramethylhexan-3-one. Alkaline hydrogen peroxide and diphenylcyclopropenone yield the same products along with benzyl phenyl ketone (equation 49). The benzyl phenyl ketone is thought to arise from addition of... 

Figure 17. Correlation between d and 2 for Type I reactions of phenyl substituted benzyl phenyl ketones [122a], calculated with = 14.3 kJ mol" 129-133, p-CH3, p-F, H, p-Cl, m-F. , 2 values of substituted benzophenones [165] were used, assuming they are proportional to those of benzyl phenyl ketones.

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