J. Org. Chem. 2001, 66, 1701-1707
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A Consecutive Double-Criegee Rearrangement Using TFPAA: Stepwise Conversion of Homoadamantane to Oxahomoadamantanes Pavel A. Krasutsky,*,† Igor V. Kolomitsyn,†,‡ Paul Kiprof,§ Robert M. Carlson,§ Nadiya A. Sydorenko,‡,§ and Andrey A. Fokin‡ Natural Resources Research Institute, 5013 Miller Trunk Highway, Duluth, Minnesota 55811-1442, USA, Department of Chemistry, University of Minnesota, 10 University Drive, Duluth, Minnesota 55812, Department of Chemistry, National Technical University of Ukraine “Kiev Polytechnic Institute”, 252056, Kiev, Peremogy Ave 37, Ukraine
[email protected] Received August 10, 2000
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-methylhomoadmantan4-ol (3) dehydration, with subsequent epoxidation of 4-methylhomoadamant-4-ene (32) to 4,5-epoxy4-methylhomoadamantane (33), acid-catalyzed isomerization of 33 to 3-methylhomoadamantan2-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. Introduction The ionic rearrangement of peroxyesters, proposed by Criegee,1 leads to ketones,2 enol ethers3 or esters.4 The reaction of ketals5 with peracids indicates the possibility of observing sequential oxygen insertion during Criegee rearrangement. Despite the significant increasing of strain energy6 as a result of oxygen insertion into the adamantane structure, a consecutive double-Criegee rearrangement was observed6 for the reaction of 2-methyladamantan-2-ol (1) with trifluoroperacetic acid (TFPAA) in trifluoroacetic acid (TFAA), with the formation of a stable (i.e., at -25 °C) 5-methyl-4,6-dioxabishomoadamant-5-yl cation (2) (Scheme 1).6 The logical next step in this research was to study the consecutive oxygen insertion into the more strained homoadamantane6,7 framework.8 It is predictable that, * To whom correspondence should be addressed. Phone: 218 720 4334. Fax: 218 720 4329. † Natural Resources Research Institute. ‡ National Technical University of Ukraine “Kiev Polytechnic Institute”. § University of Minnesota. (1) (a) Criegee, R. Chem. Ber. 1944, 77, 722. (b) Criegee, R. Ann. Chem. 1948, 560, 127. (2) Hedaya, E.; Winstein, S. J. Am. Chem. Soc. 1967, 89, 1661. (3) Goodman, R. M.; Kishi, Y. J. Org. Chem. 1994, 59, 5125. (4) Schreiber, S. L.; Liew, W.-F. Tetrahedron Lett. 1983, 24, 2363. (5) (a) Bailey, W. F.; Shih, M.-J. J. Am. Chem. Soc. 1982, 104, 1769. (b) Bailey, W. F.; Bischoff, J. J. J. Org. Chem. 1985, 50, 3009. (6) Krasutsky, P. A.; Kolomitsyn, I. V.; Kiprof, P.; Carlson, R. M.; Fokin, A. A. J. Org. Chem. 2000, 65, 3926. (7) Engler, E. M.; Andose, J. D.; Schleyer, P. v. R. J. Am. Chem. Soc. 1973, 95, 8005.
Scheme 1
in this situation, the ionic rearrangements through the bridge carbon (C4) of homoadamantane could be more complicated because of additional possibilities for olefinization9 or Wagner-Meerwein rearrangement.9 These parallel reactions may disguise the process of oxygen insertion. However, the unfolding of the entanglement of the reaction products should be helpful in the generalization of consecutive oxygen insertion process. On the basis of previous work,6 4-methylhomoadamantan-4-ol (3) was chosen as the substance for the reaction with TFPAA in TFAA. The methyl substituent, with its low migratory aptitude, was chosen on the basis of previous studies on the migratory ability of alkyl and aryl groups in acid-catalyzed Baeyer-Villiger reactions10,11 and in Criegee rearrangements10,12 as well as our own experience with 2-methyladamantan-2-ol (1)6 in TFPAA. (8) Liebman, J. F.; Greenberg, A. Chem. Rev. 1976, 76, 311. (9) Okazaki, T.; Terakawa, E.; Kitagawa, T.; Takeuchi, K. Tetrahedron Lett. 1996, 37, 1035. (10) Krow, R. G. Org. React. 1993, 43, 251. (11) (a) Strukul, G. Angew. Chem. 1998, 37, 1198. (b) Kitazume, T.; Kataoka, J. J. Fluorine Chem. 1996, 80, 157. (c) Goodman, R. M.; Kishi, Y. J. Am. Chem. Soc. 1998, 120, 9392. (12) Wistuba, E.; Ruchardt, C. Tetrahedron Lett. 1981, 22, 3389.
10.1021/jo001219z CCC: $20.00 © 2001 American Chemical Society Published on Web 02/14/2001
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J. Org. Chem., Vol. 66, No. 5, 2001 Scheme 2
Krasutsky et al. Scheme 4
Scheme 3
Scheme 5
Results and Discussion Oxygen Insertion into 4-Methylhomoadamantanol-4 (3) with TFPAA. When the alcohol 3 was reacted at room temperature with an 8-fold excess of TFPAA in TFAA, the main products (4 and 5, Scheme 2) were isolated from the reaction mixture (total yield 60%). The preparative yield of 3-ethyl-4-oxahomoadamantan5-one (4) and exo-2-hydroxy-4-oxahomoadamantane13 (5) is increased to 95% when the reaction was performed in TFPAA/TFAA/CH2Cl2. The product distribution is outlined in Scheme 2. It is worth noting from a mechanistic point of view that traces of 4-oxahomoadamantane14 (6) were also observed (
