Adamantanes electrophilic oxygenation

BTSP-CF3SO3H is an efficient electrophilic oxygenating agent for adamantane and diamantane. With adamantane, the major reaction product is 4-oxahomoadamantane in isolated yield in 79% through a C—C a-bond insertion with very little 1-adamantanol, the C—H insertion product (equations 57 and 58/. In the case of diamantane, two isomeric oxahomodiamantanes were obtained along with two isomeric bridgehead diamantanols corresponding to C—C and C—H a-bond insertions. 

Bis(trimethylsilyl)peroxide-triflic acid was also found to be an efficient electrophilic oxygenating agent.209 Adamantane gives 4-oxahomoadamantane obtained through C—C a-bond insertion ... 

Bis(trimethylsilyl)peroxide-triflic acid and sodium percarbonate-triflic acid are also efficient electrophilic oxygenating agents. Adamantane is transformed into 4-oxahomoadamantane in good yields obtained through C-C a-bond insertion [Eq. (6.57)]. 1 -Adamantanol, the C-H insertion product, is formed in a very small amount. Isomeric oxahomodiamantanes (C-C insertion) and bridgehead diamantanols (C-H insertion) are produced from diamantane. ... 

Oxygenation of 2-substituted adamantanes with methyl(trifluoromethyl)dioxirane showed a reaction constant, p = -2.31, consistent with a strongly electron-demanding transition state. Analysis of the effect of solvents on the rate yielded a positive regression coefficient with Dimroth-Reichardt Ej solvent polarity parameter. A mechanism involving an electrophilic O atom insertion has been postulated for the formation of alcohols and carbonyl compounds.201... 

For electrophilic and more bulky radicals, for example CnHal2n+i, selectivity increases dramatically. Whereas the selectivity for the radical chlorination (Table 1, entry 7) and bromination (Table 1, entry 8) of adamantane with Hal2 in CC14 is only approximately 5, for chlorinations with CC14 (Table 1, entries 9 and 10) and brominations with BrCCl3 (Table 1, entry 11) the selectivity increases to 21.5-27. Halogenations under metal-catalyzed GIF conditions (Table 1, entry 12) or in the presence of dioxirane (Table 1, entry 13) are less selective, because of the participation of oxygen-centered (GIF) or methyl (DMD) radicals. 

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