# III. Group Abstraction

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Group abstraction is possible when a group is attached to a carbon atom in a carbohydrate by a bond to a sulfur, selenium, or tellurium atom (eq 11). The abstracting radical in nearly every instance is tin-centered (eq 12)8 or silicon-centered (eq 13).9 Although group abstraction reactions can be elementary ones, they cease to be so if an intermediate with a hypervalent atom forms (Scheme 3). (Generating a hypervalent atom causes abstrac­tion to become a combination of radical addition and α-fragmentation.) Only rarely is a hyper­valent atom believed to be involved if a sulfur or selenium atom provides the link to the carbohydrate framework.10,11 (An example of a noncarbohydrate, selenide reaction that appears to involve a hypervalent selenium atom is described in Chapter 8, Section III.B.) Where the connection is to a tellurium atom, computational inves­ti­gations indicate that a radical with a hypervalent atom is likely form.10

## Contributors

Roger W. Binkley (Cleveland State University) and Edith R. Binkley (Cleveland Heights-University Heights school system)

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