Copper‐Catalyzed Synthesis of Trinuclear N‐Fused Hybrid Scaffolds by Double C(sp²)–N Bond Formation between 2‐(2‐Bromoaryl)indoles and 2‐Aminoazoles

Abstract

2-(2-Bromoaryl)indoles react with 2-aminoazoles by microwave irradiation in DMF in the presence of a catalytic amount of CuI and a base to produce trinuclear N-fused hybrid scaffolds, benzo[4,5]imidazo[1,2-a]indolo[1,2-c]quinazolines and imidazo[1,2-a]indolo[1,2-c]quinazolines in moderate to good [a]

Copper‐Catalyzed Synthesis of 5‐Arylindolo[1,2‐c]quinazolin‐6(5H)‐ones from 2‐(2‐Bromoaryl)indoles and Aryl Isocyanates under Microwave Irradiation

“…Lower reactivity of the reaction of 1 a and 2 a compared to that of 2‐(2‐bromoaryl)benzimidazole 9 and 2 a under transition metal‐free condition seems to be due to the stability of a Meisenheimer complex resulting from electronegativity difference between carbon and nitrogen (Scheme 2). [22] …”

“…The products were isolated by preparative TLC (a glass plate coated with Kieselgel 60 GF 254 , Merck). The starting 2‐(2‐bromoaryl)indoles 1 and 4 were synthesized by known methods, respectively [21,22] . Other commercially available organic and inorganic reagents were used without further purification.…”

Progress and prospects in copper-catalyzed C–H functionalization

“…Cho et al developed polynuclear N-fused hybrid scaffolds 143 from 2-(2bromoaryl)indoles 141 and 2-aminoazoles 142 under microwave irradiation (Scheme 54). 75 The reaction worked well for benzo-fused 2-aminobenzimidazoles bearing electron-decient and electron-donating substituents. The reaction was also found feasible with 2-(2-bromoaryl)indoles bearing methyl, methoxy, and uoro substituents.…”

Advances in the Synthesis of Ring-Fused Benzimidazoles and Imidazobenzimidazoles

“…More recently, 2-(2-bromoaryl)- and 2-(2-bromovinyl)benzimidazole substrates were coupled with cyanamide using CuI to give 2-aminoquinazoline and 2-aminopyrimidine hybrid structures ( Scheme 31 b) [ 97 ]. Similar conditions allowed CuI-mediated coupling and cyclization between 2-(2-bromoaryl)indoles and 2-aminoazoles [ 98 ], including 2-aminobenzimidazoles with loss of ammonia to give indole analogues of Scheme 30 b adducts [ 95 ].…”