The Photochemical C<sup>2</sup>−C<sup>6</sup>Cyclization of Enyne−Allenes: Interception of the Fulvene Diradical with a Radical Clock Ring Opening
作者:Götz Bucher、Atul A. Mahajan、Michael Schmittel
DOI:10.1021/jo900439x
日期:2009.8.21
derived from cyclopropyl ringopening. Laserflashphotolysis (LFP) studies on enyne−allene 3 point to an allene triplet excited state (transient A) as a primarily formed short-lived (τ = 430 ns) intermediate. In addition, we have obtained evidence for the formation of a diphenylmethyl-type diradical (transient C, τ = 1.0 μs) resulting from ringopening of a diphenylcyclopropane ring. C subsequently undergoes
Photochemical C<sup>2</sup>−C<sup>6</sup> Cyclization of Enyne−Allenes: Detection of a Fulvene Triplet Diradical in the Laser Flash Photolysis
作者:Götz Bucher、Atul A. Mahajan、Michael Schmittel
DOI:10.1021/jo801689w
日期:2008.11.21
products. In contrast, the photochemical C(2)-C(6) cyclization of enyne-allenes provided formal Diels-Alder and/or ene products, with higher yields for the benzannulated systems. A raise of the temperature in the photochemical cyclization of enyne-allene 1b' led to increasing amounts of the ene product in relation to that of the formal Diels-Alder product. Laserflashphotolysis at 266 and 355 nm as well