RESUMO
A catalytic protocol that reliably predicts and controls the site-selective incorporation of CO2 to a wide range of unsaturated hydrocarbons utilizing water as formal hydride source is described. This platform unlocks an opportunity to catalytically repurpose three abundant, orthogonal feedstocks under mild conditions.
RESUMO
1,6-Enynes bearing OR groups at the propargyl position generate α,ß-unsaturated gold(I)-carbenes/ gold(I) stabilized allyl cations that can be trapped by alkenes to form cyclopropanes or 1,3-diketones to give products of α-alkylation. The best migrating group is p-nitrophenyl ether, which leads to the corresponding products without racemization. Thus, an improved formal synthesis of (+)-schisanwilsonene A has been accomplished. The different competitive reaction pathways have been delineated computationally.
RESUMO
The sustainable utilization of available feedstock materials for preparing valuable compounds holds great promise to revolutionize approaches in organic synthesis. In this regard, the implementation of abundant and inexpensive carbon dioxide (CO2) as a C1 building block has recently attracted considerable attention. Among the different alternatives in CO2 fixation, the preparation of carboxylic acids, relevant motifs in pharmaceuticals and agrochemicals, is particularly appealing, thus providing a rapid and unconventional entry to building blocks that are typically prepared via waste-producing protocols. While significant advances have been realized, the utilization of simple unsaturated hydrocarbons as coupling partners in carboxylation events is undoubtedly of utmost academic and industrial relevance, as two available feedstock materials can be combined in a catalytic fashion. This review article aims to describe the main achievements on the direct carboxylation of unsaturated hydrocarbons with CO2 by using cheap and available Ni or Fe catalytic species.
RESUMO
A user-friendly Ni-catalyzed reductive carboxylation of benzylic C-N bonds with CO2 is described. This procedure outperforms state-of-the-art techniques for the carboxylation of benzyl electrophiles by avoiding commonly observed parasitic pathways, such as homodimerization or ß-hydride elimination, thus leading to new knowledge in cross-electrophile reactions.
RESUMO
A practical aminocyclization of 1,6-enynes with a wide variety of substituted anilines, including N-alkyl anilines, has been achived by using cationic [JohnPhosAu(MeCN)]SbF6 as a general purpose catalyst. The resulting adducts can be easily converted into polycyclic compounds by palladium- and gold-catalyzed reactions.
