Benzhydryl benzoates

The most detailed comparison of carbonium ions from diazonium ion and ester precursors is due to Diaz and Winstein (1966) who measured the relative rates of ion pair collapse and dissociation in the reaction of diphenyldiazomethane, DDM, with benzoic acids and in the solvolysis of benzhydryl benzoates (scheme 9). 

The first step in the decomposition of nitrosoamides 123) is formation of the diazo ester 125) which fragments to a diazonium ion pair (128)129 The ion pairs thus produced differ from those obtained in the reaction of diazoalkanes with acids. The ratio of ester to ether formed in the decomposition of rV-nitroso-fV-benzhydrylbenz-amides in alcohol is lower than that found in the reaction of diphenyldiazomethane 132) with acids, and in the solvolysis of benzhydryl benzoate (I35)135,136 This effect has been attributed to the intervention of trans-diazo ester in the decomposition of 125) which leads to a greater distance between carbocation and carbox-ylate anion. In the diazoalkane reaction attack of the acid occurs at the electron-rich carbon atom to generate the carboxylate in the immediate vicinity of the incipient carbocation. 

Retro-Baeyer-VilUger oxidation. Benzhydryl benzoates (2) are reduced to benzhydryl aryl ketones (3) by lithium naphthalenide (1) in THF at 20°. Aromatic carboxylic acids (4) are converted under these conditions into a-diketones (5). ... 

Carbinols conjugated with aromatic systems, such as benzylic alcohols [59-62], trityl (VIII), tritylone (IX), and benzhydryl alcohols [59,62,63], and 9-hydroxy-9-phenylan-throne, heteroaromatic systems [64], a-hydroxy ketones [65-67], a-hydroxy acids, and their derivatives [68-70] can also be cleaved at potentials less negative than that of the activating group. Thus the radical anion of benzyl benzoate cleaves rapidly to benzoate and benzyl radical, which is reduced to the anion protonation leads to toluene. In the absence of added proton donor, the base generated during the reduction (EGB) may cleave the ester to benzoate and benzyl alcohol [44]. 

Table 6. Oxygen scrambling and racemization results for p-substituted benzhydryl p-nitro-benzoates (54 )76)...

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