Photochemical reactions of aromatic compounds and the concept of the photon as a traceless reagent

Abstract

Electronic excitation significantly changes the reactivity of chemical compounds. Compared to ground state reactions, photochemical reactions considerably enlarge the application spectrum of a particular functional group in organic synthesis. Multistep syntheses may be simplified and perspectives for target oriented synthesis (TOS) and diversity oriented synthesis (DOS) are developed. New compound families become available or may be obtained more easily. In contrast to common chemical reagents, photons don't generate side products resulting from the transformation of a chemical reagent. Therefore, they are considered as a traceless reagent. Consequently, photochemical reactions play a central role in the methodology of sustainable chemistry. This aspect has been recognized since the beginning of the 20th century. As with many other photochemical transformations, photochemical reactions of aromatic, benzene-like compounds illustrate well the advantages in this context. Photochemical cycloadditions of aromatic compounds have been investigated for a long time. Currently, they are applied in various fields of organic synthesis. They are also studied in supramolecular structures. The phenomena of reactivity and stereoselectivity are investigated. During recent years, photochemical electron transfer mediated reactions are particularly focused. Such transformations have likewise been performed with aromatic compounds. Reactivity and selectivity as well as application to organic synthesis are studied.

Microflow photochemistry: UVC-induced [2 + 2]-photoadditions to furanone in a microcapillary reactor

“…Likewise, the removal of the photoproducts from the irradiated area minimizes the risk of photodecompositions or secondary photoreactions [12–13]. Of the many photochemical reactions [14–16], [2 + 2]-photocycloadditions are especially interesting transformations since they allow for the construction of cyclobutanes under mild conditions [17–19]. A number of intra- as well as intermolecular [2 + 2]-photocycloadditions have consequently been described under continuous-flow conditions [20–22].…”

Photochemical approach to functionalized benzobicyclo[3.2.1]octene structures via fused oxazoline derivatives from 4- and 5-(o-vinylstyryl)oxazoles

“…Related benzobicyclo[3.2.1]octen-3-ones have been prepared by the method of Lansbury from chloroallylindene [43–45], by carbene reaction from benzonorbornadiene [46–47] or by intramolecular insertion of the vinyl group into a carbon–carbon single bond using organometallic catalysts [48]. Herein we have reported a new simple method for the synthesis of functionalized benzobicyclo[3.2.1]octene derivatives using light as a traceless reagent [49]. …”

Kinon-metidi (II. dio): Fotokemijsko generiranje i razvoj primjene u fotokemoterapiji

“…traceless reagent). 80 Fotokemijskim generiranjem QM-a može se postići prostorna i vremenska kontrola nad njihovim stvaranjem, što je veoma pogodno za njihovu primjenu u biološkim sustavima, primjerice kao fotokemoterapeutika. 4 …”