Oxaadamantane derivatives

Stepanov et a/.143,144 report the ring opening of the monoxide (116) to several 2-oxaadamantane derivatives, where 116 is readily obtained by perbenzoic acid oxidation of 35. Treatment of 116 under various conditions yields different products. Thus, with aqueous acid it yields l-hydroxy-3-hydroxymethyl-2-oxaadamantane (117), with alcohols (R = CH3, C2H5) in acidic or basic media 1-alkoxy-substituted (118), and with hydrochloric acid l-chloro-3-hydroxymethyl-2-oxaadamantane(119). l-Methyl-2-oxaadaman-tane (120) is prepared by LAH reduction of the carbonyl group in 35 to alcohol 121 and subsequent cyclization with acid.140,142... 

Oxaadamantane and its derivatives are molecules of considerable interest to chemists and biologists, but until recently there was no convenient route to such compounds. Such a route has now been discovered, starting from the readily accessible 2-hydroxy-2-methyladamantane 1. Thus, oxidation of 1 by trifluoroperacetic acid in TFA at 20°C for one hour gave a mixture (actual yield not given merely described as "a good yield") of three products oxaadamantane 2 (56%), exo-4-hydroxy-2-oxaadamantane 3 (40%) and the lactone 4 (4%). 

Suggest mechanisms to account for the formation of 2,3 and 4. Note that oxaadamantane 2 is stable under the reaction conditions, and does not serve as a precursor to the hydroxy derivative 3. 

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