150723-27-6Relevant articles and documents
Triggering of the Bergman cyclization by photochemical ring contraction. Facile cycloaromatization of benzannulated cyclodeca-3,7-diene-1,5-diynes
Karpov, Grigori V.,Popik, Vladimir V.
, p. 3792 - 3793 (2008/02/02)
Eleven-membered ring enediyne 1, which incorporates an α-diazo-β-diketone moiety, undergoes efficient light-induced ring contraction to produce two isomeric ten-membered ring enediyne compounds. The latter undergo spontaneous facile Bergman cyclization at
Synthetic studies of the tandem enediyne-mono- and bis-radical cyclizations
Grissom, Janet Wisniewski,Calkins, Trevor L.,Egan, Miles
, p. 11744 - 11752 (2007/10/02)
The readily synthesized enediynes 12a-j possessing a tethered olefin radical acceptor can participate in a tandem enediyne-radical cyclization to yield dihydrobenzindene derivatives 14a-j. In the present study, the scope of this reaction was expanded to i
Kinetic and Mechanistic Studies of the Tandem Enediyne-Radical Cyclization
Grissom, Janet Wisniwski,Calkins, Trevor L.
, p. 5422 - 5427 (2007/10/02)
Enediynes 11 possesing a tethered olefin radical acceptor can participate in a tandem enediyne-radical cyclization to yield dihydrobenzindene derivatives 16.In the present study, the mechanism of this reaction was investigated utilizing kinetic studies to determine whether the mechanism was a radical chain, stepwise, or concerted process.Substrate concentration, 1,4-cyclohexadiene concentration, olefin geometry, and olefin electronics were varied.These experiments demonstrate that the reaction occurs under first-order kinetics over a wide variation in eithersubstrate or 1,4-CHD concentration.The reaction rate is also independent of olefin geometry and olefin electronics.The rate constants for the reactions were similar and ranged from 3.0E-4 s-1 to 6.0E-4 s-1.The data suggests that the tandem enediyne-radical cyclization proceeds through a distinct 1,4-diyl reactive intermediate such as 5 formed in the rate-determining enediyne cyclization step, followed by a radical cyclization to give 16.The tandem enediyne-radical cyclization mechanism is supported by trapping the intermediate biradical 18 in a tandem enediyne-6-exo-radical cyclization of 17 to give products 19a,b.
