Synthesis of diverse nitrogen fused polycyclic dihydroisoquinoline (DHIQ) derivatives via GBB-based cyclic iminium induced double-annulation cascade

Recent advances in 3-aminoindazoles as versatile synthons for the synthesis of nitrogen heterocycles

“…As a continuation of their efforts to construct nitrogen-containing molecules and drug-like products with potential bioactivities, in 2020, the Jeong group also developed a cyclic iminium induced GBB reaction of 3-aminoindazoles, 2-(2-bromoethyl)benzaldehydes and isonitriles for the formation of novel polycyclic dihydroindazolo[3′,2′:2,3]imidazo[5,1- a ]isoquinolinamines. 21 When the reactions were carried out at 78 °C in the presence of PTSA in ethanol, polycyclic N-heterocycles were obtained in good yields. This method provided a promising platform for the construction of complex nitrogen fused polycyclic dihydroisoquinoline skeletons, possessing readily available starting materials, high efficiency of bond formation, and good scalability.…”

Synthesis of Imidazo[1,2-a]pyridine-Fused 1,3-Benzodiazepine Derivatives with Anticancer Activity via a One-Pot Cascade GBB-3CR/Pd(II)-Catalyzed Azide-Isocyanide Coupling/Cyclization Process

“…Among them, the Groebke–Blackburn–Bienaymé three-component reaction (GBB-3CR) has attracted great attention which involves an aldehyde, an amine, and an isocyanide that proceeds through imine formation and subsequent formal [4 + 1] cycloaddition, resulting in a drug-like imidazopyridine structure (Scheme a) . Recently, various post-condensation transformations of the GBB-3CR have become a powerful method in the synthesis of structurally diverse heterocyclic compounds . For example, a transition-metal-free synthesis of spiro­[chromene-imidazo­[1,2- a ]­pyridin]-3′-imines was discovered by a post-GBB/6- exo -dig cyclization reaction under mild conditions .…”