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VIII. Summary

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    24631

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    Transfer of an electron from samarium(II) iodide to a carbohydrate with an elec­tron-ac­cept­ing substituent produces a radical anion. Dissociation of this radical anion gen­er­ates a carbo­hydrate radical along with an anion derived from the substituent group. A carbohydrate radical formed in this way reacts rapidly with a second molecule of SmI2 to produce an organosamarium compound. This organometallic compound can undergo reactions that include addition to a com­pound contain­ing a carbonyl group, proton capture, and elimination of a samarium-containing leaving group. In order for a radical formed from reaction of a carbohydrate deriv­ative with SmI2 to avoid imme­diate reaction with a second molecule of SmI2, a rapid, radical process must inter­vene. The one of greatest interest is radical cyclization; thus, a carbo­hydrate derivative ­that has a properly placed mul­ti­ple bond and an electron-accepting substituent reacts with samar­ium(II) iodide to a form radical that cyclizes. Carbo­­hydrates that contain a pair of properly positioned aldehydo or keto groups cyclize to form pinacols. The intermediate in the cyclization step leading to a pinacol is a radical anion. Organochromium com­plexes form and react in a manner similar to organosamarium compounds.

    This page titled VIII. Summary was last modified on Tue, 13 Sep 2022 22:34:05 GMT and is shared under a All Rights Reserved (used with permission) license and was authored, remixed, and/or curated by Roger W. Binkley and Edith R. Binkley.