Succinimidyl radical compounds

The relative reactivities of alkyltin compounds towards tert-butoxyl radicals, ketone triplets, and succinimidyl radicals are dominated by the steric effect of the alkyl ligands (R" > R"), but that towards bromine atoms follows the reverse sequence (R" < R ). 

EPR experiments on carbon-centred radicals with either a- or /J-boronic ester substituents have been reported.168 While the a-substituted radicals were modestly thermodynamically stable, the /J-substituted radicals underwent easy /J-climination. An EPR experiment on the photo-oxidation of phenolic compounds containing at least one free ortho position has indicated the formation of persistent secondary radicals derived from dimerization or polymerization from C-0 coupling.169 The structure of the succinimidyl radical has been re-examined using density functional theory with a variety of basis sets. The electronic ground state was found to be of cr-symmetry allowing for facile -scission. These conclusions were also predicted using MP2 but... 

Homolytic cleavage of a tin carbon bond in a tetraorgan-otin compound is less frequently encountered than is heterolytic cleavage. Such radicals as Bn, , and the suc-cinimidyl radical can take part in Sn2 displacement with tetraorganotins (Scheme 8). The reactivity of ITiSn in MezCO towards the succinimidyl radical is in the sequence of R = Me > Et > Pr > Bn this is the reverse of that for radical reactions of iodine and bromine. 

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