Cyclic nitronates radical cyclization

Lastly, the radical inter- and intramolecular cyclizations in the presence of one-electron oxidizing agents as a procedure for the synthesis of five-membered cyclic nitronates can be considered. Radical oxidation of a-nitro ketones (19) in the presence of disubstituted olefins under the action of Mn(OAc)3 was documented (72a) (Scheme 3.22, Eq. 1). 

Cyclization of nitro-stabilized radicals provides another method for the generation of cyclic nitronates (221). Oxidation of the aci-foim of nitroalkanes with ceric ammonium nitrate generates the ot-carbon centered radical, which in the presence of an alkene, leads to the homologation of the a-radical. In the case of a tethered alkene of appropriate length, radical addition leads to a cyclic nitronate (Scheme 2.20). 

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