m-CPBA-promoted Baeyer-Villiger oxidation of pentacyclo[6.3.0.0(2,6).0(3,10
).0(5,9)]undecan-4-one (1) afforded the corresponding lactone 2 in 93% yiel
d. Lithium aluminum hydride promoted reduction of lactones 2, 6, and 9, per
formed in. the presence of BF3. OEt2 reagent, afforded the corresponding ca
ge ethers, i.e., 4, 7, and 10, respectively Two methods that can be used to
replace a cage C=O group by ether oxygen without concomitant rearrangement
are delineated. A key step in the first of these methods employs m-CPBA pr
omoted "double Criegee rearrangement", which was used to convert pentacyclo
[6.3.0.0(2,6).0(3,10).05 9]undecan-4-one diethyl acetal (11) into 7,9-dioxa
pentacyclo[6.3.0.0(2,6).0(3,12).0(5,11)] tridecan-8-one (12). Subsequently,
12 was converted into 4-oxapentacyclo[6.3.0.0(2,6). 0(3,10).0(5,9)] undeca
ne (14) via a two-step reduction-dehydration reaction sequence. The second
method utilized PhI(OAc)(2)-I-2 reagent to convert cage lactols 15 and 17 i
nto the corresponding cage ethers, i.e., 14 and 2-oxaadamantane (18), respe
ctively.