[2+2] Cycloaddition of 1,3-Dienes by Visible Light Photocatalysis
作者:Anna E. Hurtley、Zhan Lu、Tehshik P. Yoon
DOI:10.1002/anie.201405359
日期:2014.8.18
[2+2] Photocycloadditions of 1,3‐dienes represent a powerful yet synthetically underutilized class of reactions. We report that visiblelight absorbing transition metal complexes enable the [2+2] cycloaddition of a diverse range of 1,3‐dienes. The ability to use long‐wavelength visiblelight is attractive because these reaction conditions tolerate the presence of sensitive functional groups that might
that attractive dispersion forces may be responsible for a change of the binding mode. The catalytic [2+2] photocycloaddition was shown to proceed on the triplet hypersurface with a quantum yield of 0.05. The positive effect of Lewis acids on the outcome of a given intramolecular [2+2] photocycloaddition was illustrated by optimizing the key step in a concise total synthesis of the sesquiterpene (±)‐italicene
Formation of Bicyclic Pyrroles and Furans Through an Enone Allene Photocycloaddition and Fragmentation Sequence
作者:Ginger Lutteke、Rana AlHussainy、Pauli J. Wrigstedt、B. T. B. Hue、René de Gelder、Jan H. van Maarseveen、Henk Hiemstra
DOI:10.1002/ejoc.200701017
日期:2008.2
acetonitrile at 300 nm resulted in the clean conversion of the starting materials into a mixture of photoproducts. The major product in all cases was a bicyclic pyrrole or furan fused to an eight membered ring (43–70 % yield). The formation of these products is thought to be a result of a heteroatom-induced fragmentation of the straight adduct (7). This is supported by irradiation of the carbon analogue
Radicalring-openingreactions of bicyclo[4.2.0]octanones, its C6 alkyl derivatives, and tricyclic ketones promoted by SmI2 gave cyclohexanones via fission of the external cyclobutane bond. The CO2Me, CN, and phenyl derivatives led to the production of the eight-membered ring compounds through cleavage of the central cyclobutane bond. Using this regioselective reaction, the synthesis of (±)-acorenone
Evidence for Triplet Sensitization in the Visible‐Light‐Induced [2+2] Photocycloaddition of Eniminium Ions
作者:Fabian M. Hörmann、Tim S. Chung、Elsa Rodriguez、Matthias Jakob、Thorsten Bach
DOI:10.1002/anie.201710441
日期:2018.1.15
photoexcited intermediates underwent intra- or intermolecular [2+2] photocycloaddition in good yields (50-78 %) upon irradiation at λ=433 nm or λ=457 nm. Iridium or ruthenium complexes with a sufficiently high triplet energy were identified as efficient catalysts (2.5 mol % catalyst loading) for the reaction. The intermolecular [2+2] photocycloaddition of an eniminium ion derived from a chiral secondary amine