Ru(III)-catalyzed construction of variously substituted quinolines from 2-aminoaromatic aldehydes (ketones) and isoxazoles: Isoxazoles as cyclization reagent and cyano sources

Ru(ii)-catalyzed regioselective [4 + 1] redox-neutral spirocyclization of aryl amidines with diazopyrazolones: direct access to spiro[indole-3,4′-pyrazol]-5′-ones

“…16 Even though great progress has been made, further exploration to access heterocyclic compounds with structural diversity is still highly desired. Inspired by previous studies 17 and our continuing efforts 18 toward the easy construction of heterocycles based on metal-catalyzed C(sp 2 )-H bond functionalization, herein, we disclose a cheaper and Earth abundant ruthenium-catalyzed [4 + 1] spirocyclization of aryl amidines with diazopyrazolones, affording the unprecedented spiro[indole-3,4-pyrazole]-5-(1′H)-ones (Scheme 1c). In this protocol, azaheterocycles were constructed starting from simple and easily available reactants in a "one pot" manner with excellent regioselectivity and broad functional group tolerance.…”

Synthesis of Tetrahydro-5H-indolo[2,3-b]quinolines through Copper-Catalyzed Cascade Reactions of Aza-o-quinone Methides with Indoles

“…(Figure ). , Due to the significant applications of these scaffolds in drug discovery research, many elegant strategies have been developed to prepare indolo­[2,3- b ]­quinolines, such as condensation, C–H bond amination reaction, cycloaddition, cascade cyclization, ring-opening and expansion, and other related transformations . However, most of these methods usually suffered from the use of prefunctionalized indole or quinoline derivatives as starting materials, low overall yield of the products, and lack of scaffold diversity and flexibility.…”