7694-30-6Relevant articles and documents
Effect of Reaction Media on Photosensitized [2+2]-Cycloaddition of Cinnamates
Abramov, Alex,Reiser, Oliver,Díaz Díaz, David
, p. 649 - 656 (2020/05/25)
The outcome of photosensitized [2+2]-cycloaddition reactions of various cinnamates has been compared in different reaction media, including homogeneous organic solutions under inert conditions, degassed water, and aerated physical gels. The reactions were performed under LED blue light (λmax=455 nm) irradiation and [Ir{dF(CF3)ppy}2(dtb-bpy)]PF6 (1.0 mol%) as photocatalyst. The processes were optimized taking into consideration solvent, gelator, and substrate. Comparative kinetics analyses, as well as the effect of the reaction media on the diastereoselectivity of the process, were evaluated during this investigation. In a number of cases, carrying out the reaction in a less polar solvent, like toluene or highly polar solvent, like water had a tremendous impact on the diastereoselectivity of the process, pointing towards an effect on the stabilization of the putative diradical intermediate in this medium. Moreover, while for reactions run in homogeneous solution oxygen needs to be excluded, no erosion in yield is observed when the photoadditions were run in aerated gel media.
Photosensitised regioselective [2+2]-cycloaddition of cinnamates and related alkenes
Pagire, Santosh K.,Hossain, Asik,Traub, Lukas,Kerres, Sabine,Reiser, Oliver
supporting information, p. 12072 - 12075 (2017/11/14)
An efficient method for the synthesis of substituted cyclobutanes from cinnamates, chalcones, and styrenes has been developed utilizing a visible-light triplet sensitisation mode. This reaction provides a diverse range of substituted cyclobutanes in high yields under mild conditions without the need of external additives. Good regioselectivity is obtained due to strong π-π-stacking of arene moieties, whereas diastereoselectivity relies on the electronic effects or ortho-substitution of the arene substrate. The utility of this transformation is demonstrated by the formal synthesis of the lignane natural product (±)-Tanegool.
Photochemical Generation of 1,4-Diphenylbutane-1,4-diyl
Kohmoto, Shigeo,Yamada, Kazuhito,Joshi, Umesh,Kawatuji, Teruyuki,Yamamoto, Makoto,Yamada, Kazutoshi
, p. 127 - 129 (2007/10/02)
Photochemical deazetation of 3,6-diphenyl-3,4,5,6-tetrahydropyrazine (1) was re-examined; evidence was obtained for trapping of a diradical intermediate (2) by oxygen when (1) was photolysed in the absence of solvent.