A consecutive double-Criegee rearrangement using TFPAA: stepwise conversion of homoadamantane to oxahomoadamantanes.
Rearrangement of 4-methylhomoadamantan-4-ol (1) with trifluoroperacetic acid (TFPAA) in trifluoroacetic acid (TFAA) proceeds with the formation of 4-oxahomoadamantane 6 and its derivatives (4 and 5). 2-exo-Hydroxy-4-oxahomoadamantane (5) and 6 were identified as a result of consecutive O-insertion Criegee rearrangement processes. The absence of methyl trifluoroacetate and methyl trifluoroperacetate among the reaction products, as well as the presence of acetyltrifluoroacetyl peroxide, is consistent with a double rather that a triple oxygen insertion during the course of the Criegee reaction. A mechanism involving initial Criegee rearrangement followed by a Baeyer-Villiger reaction is also excluded by kinetic considerations. The parallel formation of 4-ethyl-3-oxahomoadamantan-2-one (4) was determined to be the result of 4-methylhomoadmantan-4-ol (3) dehydration, with subsequent epoxidation of 4-methylhomoadamant-4-ene (32) to 4,5-epoxy-4-methylhomoadamantane (33), acid-catalyzed isomerization of 33 to 3-methylhomoadamantan-2-one (34), and Baeyer-Villiger oxidation to 3-methyl-5-oxabishomoadamantan-6-one (35). This sequence of reactions was followed by the acid-catalyzed isomerization to the final product 4. The proposed mechanisms for these transformations are discussed on the basis of model experiments and supporting density functional theory (DFT) calculations.
Natural Resources Research Institute, 5013 Miller Trunk Highway, Duluth, MN 55811-1442, USA. pkrakuts@d.umn.edu
P A
PA
Krasutsky
I V
IV
Kolomitsyn
P
P
Kiprof
R M
RM
Carlson
N A
NA
Sydorenko
A A
AA
Fokin