Exploiting Hydrazones To Improve the Efficiency of 6π-Electrocyclization Reactions of 1-Azatrienes

Gold(I)-Catalyzed Intramolecular 7-endo-dig Cyclization of Triene-Yne Systems: New Access towards Azulenothiophenes

We report the direct synthesis of new azulene derivatives through gold-catalyzed cyclization reactions. A five-membered ring as backbone in the applied triene-yne substrates turned out to be crucial to induce the 7-endo-dig cyclization mode necessary to trigger azulene formation. The obtained targets are of high interest due to their potential applications in different fields, like organic materials, medicine or cosmetics. UV/Vis spectra and cyclic voltammetry were measured, based on these the electronic properties were determined. Short two or three step sequences towards the applied starting materials make this approach synthetically highly attractive.

Microwave-Assisted Palladium-Catalyzed Reductive Cyclization/Ring-Opening/Aromatization Cascade of Oxazolidines to Isoquinolines

An efficient palladium-catalyzed reaction of N-propargyl oxazolidines for the construction of 4-substituted isoquinolines under microwave irradiation is developed. This transformation proceeds through a sequential palladium-catalyzed reductive cyclization/ring-opening/aromatization cascade via C-O and C-N bond cleavages of the oxazolidine ring. The practical value of this method has also been explored by conducting a millimole-scale reaction, as well as by transforming the isoquinoline into a key intermediate for the synthesis of a lamellarin analogue.

Design and Synthesis of Fused Pyridine Building Blocks for Automated Library Generation

We demonstrate that a diboration-electrocyclization sequence provides access to a range of pyridine-fused, small-molecule boronic ester building blocks, and that these are amenable to high-throughput synthesis leading to biaryl and ether-linked compound libraries. Moreover, the implementation of an integrated physicochemical and ADME profiling workflow allows accelerated design of novel lead compounds for application in drug-discovery projects.

Transition metal-free cyclobutene rearrangement in fused naphthalen-1-ones: controlled access to functionalized quinones

The divergent preparation of 1,4-naphthoquinones and tetraphene-7,12-diones, which bear the ABCD-ring of landomycins, has been accomplished directly through oxidative reorganization of previously non-isolable cyclobuta[a]naphthalen-4(2H)-ones.