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IX. Summary

  • Page ID
    24061
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    Aldehydo and keto groups in carbohydrates react internally with carbon-cen­tered radicals to form cyclic alkoxy radicals. Most of these reac­tions involve aldehydes; both five- and six-mem­bered rings can be formed. When ring opening of the newly formed alkoxy radical takes place, it does so to produce the more stable of the two possible, carbon-centered radicals. Such ring opening can be part of a process that causes aldehydo group migration.

    Tin-centered radicals add to aldehydes to generate tin ketyls, inter­mediates that can add to multiple bonds. Samarium ketyls, more common than their tin counterparts, undergo similar re­ac­tion. Reaction of samarium(II) iodide with carbohydrates containing two appropriately placed aldehydo groups converts one group to a ketyl that then adds to the second in route to formation of a pinacol.

    Ketone photolysis forms carbon-centered radicals by breaking the bond between the car­bonyl carbon atom and one of the α carbon atoms (an α-cleavage). Typical radical reactions then take place; in addition, α-cleav­age in some nucleotides and oligonucleotides is followed by radical cation forma­tion. α-Cleavage and hydrogen-atom abstraction take place in cyclic ketones to produce diradicals.


    This page titled IX. Summary 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.

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