1. FIELD OF THE INVENTION
This invention relates to isomerization of homoadamantane. More particularly, this invention relates to a process for preparing tricyclo[5.3.1.0.sup.3,8 ]undecane (II) (hereinafter referred to as "4-homoisotwistane") by isomerizing homoadamantane (I) as shown by the following reaction scheme: ##SPC1##
As is seen from formula (II), 4-homoisotwistane (II) is a tricyclic saturated aliphatic hydrocarbon having a cagelike molecular structure. It can be transformed to 1-methyladamantane, a known useful compound as described in U.S. Ser. Nos. 485,068 and 485,069, both filed July 2, 1974 now U.S. Pat. No. 3,894,100 and 3,894,101 respectively. In view of its molecular structure, 4-homoisotwistane will be useful as an antiviral agent, a modifier moiety for various pharmaceutical compounds, an additive for lubricating oils, a high-pressure lubricant, a rust-preventive agent, an oiling agent for fibers and the like, in the same manner as known adamantane compounds. See the section entitled "Adamantane" in the Supplement Volume of Kirk-Othmer's "Encyclopedia of Chemical Technology".
2. DESCRIPTION OF THE PRIOR ART
Several processes for the synthesis of 4-homoisotwistane (II) are known in the art. For example, the synthesis of this compound is disclosed by Krantz et al, Chem. Commun., 1287 (1971) and J. Amer. Chem. Soc., 95, 5662 (1973), Majerski et al, Tetrahedron Lett., 4915 (1973), and Schleyer et al, Chemistry Lett., 1189 (1973).
We previously found that 4-homoisotwistane (II) can be synthesized by isomerizing, in the presence of an acid catalyst, 5,6-exo-tetramethyleneorbornane (III) of the following formula: ##SPC2##
And 5,6-trimethylenebicyclo[2.2.2]octane (IV) of the following formula: ##SPC3##
(see Chemistry Lett., 1185, (1973) and Japanese Patent Applications No. 77621 (U.S. Ser. No. 485 068 now U.S. Pat. No. 3,894,100) and No. 77622/73 (U.S. Ser. No. 485 067)).