Phenol ring ketones

Thioglycohc acid is recommended as a cocatalyst with strong mineral acid in the manufacture of bisphenol A by the condensation of phenol and acetone. The effect of the mercapto group (mercaptocarboxyhc acid) is attributed to the formation of a more stable carbanion intermediate of the ketone that can alkylate the phenol ring faster. The total amount of the by-products is considerably reduced (52). 

Vinyltrimethylstannanes react with xenon difluoride in dichloromethane at room temperature in the presence of equimolar (or a 50 Vo excess) of silver trifluoromethanesulfonate and a catalytical (0.1 equiv) quantity of 2,6-di-/e/7-butyl-4-methylpyridine to form the corresponding vinyl fluorides in high to moderate yields.54 57 The substitution reaction is tolerant to various functional groups, such as ketones, esters, carbamates, ketals, ethers, phenol rings and tertiary alcohols. As byproducts corresponding alkenes have been detected due to pro-tiodestannylation. 

The introduction of additional hydroxy groups into the phenolic ring assists the development of a ketonic character because the energy released by formation of multiple keto groups compensates for the loss of resonance stabilization. There are many reports concerning the ability of polyhydric phenols to react as tautomeric keto forms. For instance, the conversion of phenol into aniline proceeds under very drastic conditions (350-450 °C, 50-60 bar) and the substitution of one hydroxy group in resorcinol by an amino group... 

Fig. 15.2.8). These included the conversion of phenolic rings into cyclic ketones and nitration of the rings. Methylol and methyl groups are also similarly nitrated. 

Oxygen has been identified in carboxylic, phenolic, and ketonic locations (55, 56, 63-65) but is not usually regarded as being located primarily in heteroaromatic ring systems. In the context of polyhydroxy aromatic nuclei, it is of interest to note that pyrolysis of asphaltenes at 800 °C results in the formation of resorcinol (63), implying that such functions may indeed exist in the native material. 

Pyrolysis of lignin and wood at 650°C yields as pyrolysis products phenols, aldehydes, ketones, acids, and alcohols, generally with the retention of original substituents (OH, OCH3) on the phenyl ring (Figure 8.4). ... 

Ozone (s. a. under (CH COO)2Co) Ketones from phenol ring viaa,/ -ethylene-y-hydroperoxy-7-lactones with retroaldol reaction... 

In 2008, Nicolaou andLi reported a synthesis of diversonol (932) (Scheme 13.14) (635). The synthesis involved the nucleophilic addition of a lithiated cyclohexene species derived from bromide 938 with the allyl-protected aldehyde 939, followed by oxidation, desilylation, deallylation, and spontaneous xanthone-ring closure of the intermediate phenol (not shown). As in the Brdse synthesis, the enol moiety is oxidized and the C-ring ketone reduced with NaBH4 to generate diversonol (932), which was obtained in eight steps from cyclohexenone 937. 

The methylenation of esters or lactones with 30, followed by further transformation, constitutes a useful synthetic protocol (Scheme 4.27). A carbonyl methyl-enation-Claisen rearrangement strategy using 30 is employed for the construction of medium- and large-ring ketones from lactones [78]. A phenol derivative has also been synthesized by treatment of a protected quinol ester with 30, which involves thermal rearrangement of the intermediate vinyl ether [79]. 

The photohydration of an unsaturated moiety on a phenol ring was first reported by Ferris and Antonucci for o-hydroxyphenylacetylene (30), which yielded ketone 31, presumably via initial formation of enol 32 ... 

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