The brex-5-yl system. A uniquely structured norbornyl homolog

Abstract

The brexane skeleton functionalized at C-5 is perceived as potentially useful for various mechanistic studies. Our present objective was to prepare and characterize brex-5-yl derivatives and to seek spectroscopic evidence for geometric distortion in the skeleton. The structures synthesized include brex-4-ene, brexan-5-one, both of the epimeric brexan-5-ols, and various derivatives of these compounds. Spectroscopic data (ir, 1H nmr, and uv) are compared with those from relevant model compounds and are most simply interpreted on the basis of a twist in the brexyl skeleton. This distortion imparts more exo character to the C—H bonds at C-4 and more endo character to the C—H bonds at C-5. As an extension of the useful terms geminal and vicinal, we propose the word hominal to represent a 1,3-relationship between two groups.