The
implications of the use of surfactant TPGS-750-M in water as
a micellar reaction medium on the concomitant aqueous waste streams
and their sustainable disposal have been studied. Biodegradability,
log P
ow, solubility, and German
water hazard class of the surfactant have been determined and enabled
establishment of a waste water concept, which builds on the lipophilicity
and ester group lability of the molecule. The presented data and examples
suggest preferred ways for designing surfactant processes and their
aqueous waste streams in a sustainable manner.
A general anti-Baldwin radical 4-exo-dig cyclization from nitrogen-substituted alkynes is reported. Upon reaction with a heteroleptic copper complex in the presence of an amine and under visible light irradiation, a range of ynamides were shown to smoothly cyclize to the corresponding azetidines, useful building blocks in natural product synthesis and medicinal chemistry, with full control of the regioselectivity of the cyclization resulting from a unique and underrated radical 4-exo-dig pathway.
Perfluoroalkylated (hetero)arenes represent an extremely important family of molecules commonly utilized in many areas such as medicinal chemistry, agrochemistry and material sciences. Due to their unique properties, they have attracted significant interest from synthetic chemists and various methods have been developed for their synthesis. Among them, the direct perfluoroalkylation of C(sp 2 )À H bonds in (hetero)arenes is one of the most attractive and straightforward ones, provided that it proceeds with high levels of regioselectivity. In this review article, a comprehensive overview of advances in this field is presented, with a special focus on the reaction mechanisms involved in these transformations and their regioselectivity. All methods available have been classified according to the nature of the perfluoroalkyl chain introduced, trifluoromethylation reactions being overviewed in a separate section, and to the nature of the reagents/catalysts required.
A general and efficient procedure for the copper-catalyzed photoinduced radical domino cyclization of ynamides and cyanamides providing an efficient access to complex tri-, tetra- and pentacyclic nitrogen heterocycles is reported. Upon visible light irradiation in the presence of catalytic amounts of [(DPEphos)(bcp)Cu]PF6 and an amine, a range of unactivated aryl and alkyl iodides were shown to be smoothly transformed to the corresponding radical species, initiating the radical domino cyclization. This procedure provides a unified entry to rosettacin, luotonin A, and deoxyvasicinone that could be efficiently prepared in a limited number of steps.
Organic transformations can broadly be classified into four categories including cationic, anionic, pericyclic and radical reactions. While the last category has been known for decades to provide remarkably efficient synthetic pathways, it has long been hampered by the need for toxic
reagents, which considerably limited its impact on chemical synthesis. This situation has come to an end with the introduction of new concepts for the generation of radical species, photoredox catalysis – which simply relies on the use of a catalyst that can be activated upon visible
light irradiation – certainly being the most efficient one. The state-of-the-art catalysts mostly rely on the use of ruthenium and iridium complexes and organic dyes, which still considerably limits their broad implementation in chemical processes: alternative readily available catalysts
based on inexpensive, environmentally benign base metals are therefore strongly needed. Furthermore, expanding the toolbox of methods based on photoredox catalysis will facilitate the discovery of new light-mediated transformations. This article details the use of a simple copper complex which,
upon activation with blue light, can initiate a broad range of radical reactions.
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