Hydride Transfer Reduction-Rearrangement of 5,6-exo-Trimethylene-2-Norbornylcarbinols. A Convenient Synthesis of 4-Homoisotwistane

Abstract

4-Homoisotwistane (tricyclo [5. 3. 1. 0^{3, 8}] undecane) (I) has been shown to be one of the most stable intermediates in adamantane rearrangement of various tricycloundecane precursors.^1–6 It was also indicated in our experiments that proper choice in precursors and catalysts resulted in almost exclusive formation of 4-homoisotwistane.^3–5 Thus isomerization of 2,3-trimethylenebicyclo [2. 2. 2] octane (tricyclo [5. 2. 2. 0^2,6] undecane) (II) in excess 95% sulfuric acid offered an effective method of synthesizing 4-homoisotwistane.⁷