Photochemical Myers−Saito and C<sup>2</sup>−C<sup>6</sup> Cyclizations of Enyne−Allenes: Direct Detection of Intermediates in Solution
作者:Michael Schmittel、Atul A. Mahajan、Götz Bucher
DOI:10.1021/ja044890k
日期:2005.4.1
Several examples of the photochemical Myers-Saito and C2-C6 cyclization of enyne-allenes are described. The presence of a triplet sensitizing unit at the allene terminus and laser flash photolysis results suggest that the cyclization proceeds along the triplet manifold. An intermediate with tau = 33 +/- 5 mus was tentatively assigned to a singlet biradical.
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