Nitrogen Radicals as Synthesis Intermediates. N-Halamide Rearrangements and Additions to Unsaturated Hydrocarbons

Synthesis of bridged azabicyclic ketones. Solvolysis of enol ether ethylene ketal N-cholramines in acidic medium

“…5 In addition, the fact that we observe a strong solvent effect, as evidenced in going from pure trifluoroacetic acid to a mixture of CF3C02H-MeOH, supports an ionic process rather than a radical pathway.…”

“…N-chloramine decomposition may follow various mechanistic pathways. In acidic medium it is possible to consider: (i) radical reactions involving either addition of an aminium radical (~~f i h ) to a double bond (4,5) or hydrogen abstraction from a saturated carbon atom, i.e., the Hofmann-Loeffler-Freytag reaction (18); (ii) ionic reactions such as electrophilic chlorination (1,3) or possibly nitrenium ion additions (13).…”

Microwave assisted N-chlorination of secondary amides

“…3 Photolysis of N-haloamides gives amidyl radicals and halogen atom intermediates. [4][5][6][7][8][9] The amidyl radicals so produced undergo efficient intramolecular addition to olefinic bonds. 5,[9][10][11][12] Olefinic amidyl radicals can ring-close to lactams or N-heterocyclic amides.…”

The Photochemical Isomerization of N-Bromo-α,β-unsaturated Lactams; An Intermolecular Allylic Bromination Process Involving a Probable Bromine Radical Chain

“…A priori, the u.v. irradiation of l b and 2b might be expected to lead primarily to allylic bromination and/or, possibly, addition to the olefinic double bond (3)(4)(5)(6).…”

“…However, it 1 2 n R -H n R = H 6 R L = B r b R = B r has been shown that intramolecular hydrogen abstraction by saturated aliphatic aml'dyl radicals is a highly selective reaction4 which requiresa sixmembered ring transition state (3,(8)(9)(10) as is the case for aminium (1 1) and alkoxy (12) radicals in general. Furthermore, Edwards et al (13) have recently observed that whereas saturated eightand nine-membered ring N-chloro lactams transferred chlorine efficiently through intramolecular hydrogen abstraction, the seven-membered ring analog exclusively yields the parent lactam through intermolecular hydrogen abstraction from the solvent.…”