Naslov
Free-radical reactions of a [3.1.1]propellane, 2, 4-methano-2, 4-didehydroadamantane

Autori
Mlinarić-Majerski, Kata ; Majerski, Zdenko ; Rakvin, Boris ; Veksli, Zorica

Izvornik
Journal of organic chemistry (0022-3263) 54 (1989), 3; 545-548

Vrsta, podvrsta i kategorija rada
Radovi u časopisima, članak, znanstveni

Ključne riječi
propellane ; diradicaloid ; free-radical reactions

Sažetak
2, 4-Methano-2, 4-didehydroadamantane (1), a prototype small propellane, readily added disulfides and carbon tetrachloride across the central bond to give the corresponding 2, 4-disubstituted 2, 4-methanoadamantanes. Methyl phenyl disulfide as well as mixtures of dimethyl disulfide and diphenyl disulfide produced 2-(methylthio)-4-(phenylthio)-2, 4-methanoadamantane (4) in addition to the symmetrical disulfides, 2, 4-bis(methylthio)-2, 4-methanoadamantane (2) and 2, 4-bis(phenylthio)-2, 4-methanoadamantane (3). The simultaneous formation of 2, 3, and 4 provides strong evidence that these reactions are indeed free-radical chain processes. Carbon tetrachloride, when present in an excess over 1, generated a strong ESR signal corresponding to the 4-substituted 2, 4-methano-2-adamantyl radical (5). The structure of this radical was confirmed by ESR of the radical derived from 2, 4-methano-2, 4-didehydroadamantane-11, 11-d2 (1a). The ESR signal appeared only when carbon tetrachloride was present in an excess over 1, which indicated that 1 was a very efficient free-radical trap. Propellane 1 spontaneously reacted with α-phenyl-N-tert-butylnitrone, a spin-trapping agent, and p-benzoquinone, an electron-deficient olefin. The former reaction led to the corresponding nitroxide radical, and the latter one gave 4-methyleneadamantane-2-spiro-7′-bicyclo[4.1.0]hept-3′-ene-2′, 5′-dione (9), most probably via a diradical intermediate. The behavior of 1 in all these reactions is consistent with the partial diradical character of this small propellane and suggests the term "diradicaloid" for such species.

Izvorni jezik
Engleski

Znanstvena područja
Kemija

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