4,5-CYCLOPROPANOCHOLESTAN-3-BETA-OL SUBSTRATES FOR CHOLESTEROL OXIDASE AND THEIR H-1-NMR ASSIGNMENTS

We have assayed 4,5-cyclopropanocholestan-3-ols and 4,5-cyclopropanoch olestan-3-ones and tested them as substrates and inhibitors of cholest erol oxidase. The 4,5-cyclopropanocholestan-3 beta-ols (alpha and beta ) are substrates of cholesterol oxidase that are converted to their re spective ketones 1000-fold more slowly than cholesterol. The induced r ing-current effects of a cyclopropane ring are clearly illustrated in the H-1 NMR spectra of these sterols. These shielding effects are dram atic because of the rigidity of the steroid backbone. Assignments of t he H-1 resonances of the A, B, and cyclopropyl rings of the sterols ha ve been made using DQF-COSY and NOESY experiments. We have assigned th e upheld multiplet at approximately 0.5 ppm to H-6 alpha in both isome rs. H-6 alpha is Shielded by the cyclopropyl sigma bond. H-6 beta is d eshielded by the cyclopropane ring and appears at approximately 2.0 pp m in both isomers.