Search

A new C-center radical-triggered bicyclization cascade of N-tethered 1,7-enynes for forming 28 examples of biologically interesting spirocyclohexadienone-containing cyclopenta[c]quinolin-4-ones with two all-carbon quaternary stereocenters has been established under mild conditions. The in situ generated diazonium salts from 4-methoxyanilines and t-BuONO are served as 4-methoxyphenyl precursors without additional oxidant, enabling 6-exo-dig cyclization/5-exo-trigipso-cyclization to construct three new C-C bonds through metal-free dearomatization. The reaction also features broad substrate scope, annulation efficiency, and high functional group tolerance. [ABSTRACT FROM AUTHOR]

A base-free process to access indole-fused polyheterocycles via a highly efficient and atom-economic palladium-catalyzed intramolecular cross dehydrogenetive coupling (CDC) reaction of 4-aniline substituted coumarins, quinolinones, and pyrones has been developed. A wide range of indolo[3,2-c]coumarins, indolo[3,2-c]quinolinones, and indolo[3,2-c]pyrones can be facilely afforded in good to excellent yields (up to 99%). [ABSTRACT FROM AUTHOR]

In the addition of TMEDA in toluene, aryl Grignards could effectively and site-specifically ortho-arylate electron-deficient heteroarenes under mild conditions. This endeavor successfully changed the old low-yielding reaction, aryl Grignard addition to N-heteroarenes, into an efficient procedure for heterobiaryls. The combination of the inexpensive aryl Grignards, TMEDA, the cost-free air, no use of any transition-metal catalyst, the mild reaction conditions, and the high-yielding gram-scale results enables this new procedure to be cost-effective and potentially utilizable in industry. [ABSTRACT FROM AUTHOR]

An interesting aldehyde- and ketone-induced intermolecular tandem decarboxylation-coupling (Csp3Csp) catalyzed by copper with usc of natural α-amino acids as starting materials is developed under neutral conditions with the production of CO2 and H2O as the only byproducts. Various functionalized nitrogen-containing compounds were obtained by this method. In these processes, interesting regioselecsivites of the alkylation were observed, which has been rationalized by the relative stability of proposed resonance structures based on computation methods. [ABSTRACT FROM AUTHOR]