Periodic Reporting for period 3 - ELDORADO (Electrophilicity-Lifting Directed by Organochalcogen Redox-Auxiliaries and Diversiform Organocatalysis)
Periodo di rendicontazione: 2022-08-01 al 2024-01-31
The formation of C(sp2)–heteroatom bonds by catalytic means arguably belongs to the group of most heavily investigated and sought-after reactions in the area of modern chemical synthesis. Among the most common protocols used to forge such bond motifs rank transition metal-catalyzed cross couplings. Even today, many of such protocols still suffer from suboptimal redox-economy, since often at least one of the reaction partners has to be used in a non-optimal oxidation states in simply to exhibit the desired reactivity. The dependence on redox-suboptimal coupling partners can bear significant disadvantages, such as cost-inefficiency and co-production of environmentally critical waste. One of the key-goals in this project is to overcome such disadvantages by using photo-aerobically driven chalcogen-π-acid catalysts for the redox-economic formation of C(sp2)–heteroatom as well as C(sp2)–C(sp2) bonds. Our findings already indicate that particularly alkenes can serve as non-activated coupling partners for a broad series of non-preactivated heteroatomic nucleophiles. In combination with our studies on chiral chalcogen-π-acid catalysts the future outcomes of this project are anticipated to pave a complementary entryway toward axially chiral target molecules.
Iterative reaction manifolds arguably represent one of the most versatile and reliable approaches toward structural complexity in chemistry. Looking at how nature assembles complex molecules, such as proteins, polysaccharides or polyketides, iterativity remains a common feature in the biosynthesis of all of these compound classes. A major leap toward mimicking this profound assembly logic has been taken by the use of Se-residues as redox auxiliaries within selenohydrins to photocatalytically initiate 1,2-migrations to furnish α-branched carbonyls. These latter species are easily converted into selenohydrins that are extended by one C-atom compared to the parent selenohydrin. This unprecedented assembly concept is expected to be very suitable for the generalized synthesis of complex natural products, such as polyketides, with important pharmaceutical activities.