Synthesis of Polyheteroaromatic Compounds via Rhodium-Catalyzed Multiple C–H Bond Activation and Oxidative Annulation

Abstract

Polyheteroaromatic compounds are potential optoelectronic conjugated materials due to their electro- and photochemical properties. Transition-metal-catalyzed multiple C-H activation and sequential oxidative annulation allows rapidly assembling of those compounds from readily available starting materials. A rhodium-catalyzed cascade oxidative annulation of β-enamino esters or 4-aminocoumarins with internal alkynes is described to access those compounds, featuring multiple C-H/N-H bond cleavages and sequential C-C/C-N bond formations in one pot.

Recent Advances in Heterocyclic Nanographenes and Other Polycyclic Heteroaromatic Compounds

“…Several nitrogen-containing phenalenoids were obtained using a rhodium-catalyzed oxidative annulation of β-enamino esters with internal alkynes, described by Sun et al ( Scheme 186 ). 364 For instance, diphenylacetylene and the unprotected β-enamino ester 186.1 could be reacted in the presence of [Cp*RhCl 2 ] 2 and Cu(OAc) 2 to afford 186.2 in 73% yield. When 4-aminocoumarins were used as substrates in the same reaction, extended systems, such as 186.4 , were formed.…”

Recent Advances for the Synthesis of N‐Unsubstituted Pyrroles

“…A Rh‐catalyzed cascade oxidative annulation of β ‐enamino esters 240 or 4‐aminocoumarins 243 with internal alkynes 241 was discovered by Jiangtao Sun et al [78] . For example, when alkyne 241 was used, the pyrrole 242 was obtained in 92 % yield (Scheme 80).…”

Recent Advances in C–H Activation for the Synthesis of π-Extended Materials

“…APEX reactions forming heterocycle-doped PAH systems can be split into two categories: reactions in which already heteroatom-containing substrates undergo C–H annulation, − and those in which hydrocarbon scaffolds react with heteroatom-embedded APEX reagents. − …”