Pd-catalyzed regioselective rollover dual C-H annulation cascade: facile approach to phenanthrene derivatives

Electrochemical Synthesis of Spirolactones from α-Tetralone Derivatives with Methanol as a C1 Source

Spirolactones are widely found in pharmaceuticals and bioactive natural products. However, efficient and environmentally friendly approaches to accessing spirolactones are still highly desirable. Herein, a novel electrochemical synthesis of spirolactones from α-tetralone derivatives with methanol as a C1 source is described. This electrochemical reaction exhibits a high efficiency and good functional group tolerance.

Diversity-Oriented Synthesis of Indole-Fused Polycyclic Scaffolds via Rhodium-Catalyzed NH-Indole-Directed C-H Coupling of 2-Phenyl-1H-indoles with Propargylic Alcohol Derivatives

Diversity-oriented synthesis strategy for the efficient assembly of indole-fused polycyclic scaffolds via rhodium-catalyzed NH-indole-directed C-H coupling with propargylic alcohol derivatives in a regioselective manner was developed. Five 2-phenyl-1H-indole-embedded core skeletons were synthesized. In particular, three different indole-fused exo-olefin-containing polycycles were realized, which may be manipulated for further chemistry.

Pd-Catalyzed Vicinal Intermolecular Annulations of Iodoarenes, Indoles, and Carbazoles with Enynes

Reaching the formidable C-H corners has been one of the top priorities of organic chemists in the recent past. This prompted us to disclose herein a vicinal annulation of 2-iodo benzoates, indoles, and carbazoles with N-embedded 1,6-enynes through 7-/8-membered palladacycles. The relay does not require the assistance of any directing group, leading to multicyclic scaffolds, which are readily diversified to an array of adducts (with new functional tethers and/or three contiguous stereocenters), in which we showcase a rare benzylic mono-oxygenation.

Transition metal-free and temperature dependent one-pot access to phenanthrene-fused heterocycles via a 1,3-dipolar cycloaddition pathway

A versatile, operationally simple, temperature-dependent, and transition metal-free one-pot protocol has been devised for the preparation of novel phenanthrene-fused pyrazoles. Notably, the overall process involved an intermolecular condensation, an intramolecular 1,3-dipolar cycloaddition, and an aromatization sequence starting from biaryl-2,2'-aldehydes bearing enoate esters with various hydrazine hydrochlorides. Notably, the sequential one-pot three-component operation has also been achieved. Importantly, it was also shown that this protocol was amenable to hydroxylamine hydrochloride as the nitrogen source and furnished phenanthrene-fused isoxazoles. Notably, the temperature dependent nature of this protocol was also demonstrated, which led to the formation of dealkoxylcarbonylated phenanthrene-fused pyrazoles at slightly higher temperatures and longer reaction times. Remarkably, this metal-free protocol effectively constructed two C-N bonds and one C-C bond and exhibited a broad substrate scope.