Verruculogen an fumitremorgin A are bioactive alkaloids that contain a unique eight-membered endoperoxide. Although related natural products such as fumitremorgins B and C have been previously synthesized, we report the first synthesis of the more complex, endoperoxide-containing members of this family. A concise route to verruculogen and fumitremorgin A relied not only on a hydroperoxide/indole hemiaminal cyclization, but also on the ability to access the seemingly simple starting material, 6-methoxytryptophan. An iridium-catalyzed C–H borylation/Chan–Lam procedure guided by an N-TIPS group enabled the conversion of a tryptophan derivative into a 6-methoxytryptophan derivative, proving to be a general way to functionalize the C6 position of an N,C3-disubstituted indole for the synthesis of indole-containing natural products and pharmaceuticals.
A combined palladium- and photoredox-catalyzed C-H olefination enables the synthesis of indoles. By using visible light, the direct C-H activation of aromatic enamines can be achieved and a variety of indole derivatives can be obtained in good yields under mild reaction conditions.
Let there be light: A heterogeneous photocatalytic system based on easily recyclable TiO(2) or ZnO allows cross dehydrogenative coupling reactions of tertiary amines. The newly developed protocols have successfully been applied to various C-C and C-P bond-forming reactions to provide nitro amines as well as amino ketones, nitriles and phosphonates.
The direct arylation of heteroaromatics with an easily accessible and recyclable, heterogeneous TiO 2 catalyst and visible light was developed. Electron-rich as well as electron-poor heteroarenes could be applied in this transformation, and the corresponding products were isolated in very good yields. Azoethers were detected as reactive intermediates, and the unexpected role of TiO 2 in their formation as well as reaction was established.
The development of new antimalarial
therapeutics is necessary to address the increasing resistance to
current drugs. Bicyclic azetidines targeting Plasmodium falciparum phenylalanyl-tRNA synthetase comprise one promising new class of
antimalarials, especially due to their activities against three stages
of the parasite’s life cycle, but a lengthy synthetic route
to these compounds may affect the feasibility of delivering new therapeutic
agents within the cost constraints of antimalarial drugs. Here, we
report an efficient synthesis of antimalarial compound BRD3914 (EC50 = 15 nM) that hinges on a Pd-catalyzed, directed C(sp3)–H arylation of azetidines at the C3 position. This
newly developed protocol exhibits a broad substrate scope and provides
access to valuable, stereochemically defined building blocks. BRD3914
was evaluated in P. falciparum-infected mice,
providing a cure after four oral doses.
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