Imidazodipyridines via DMAP Catalyzed Domino N−H Carbonylation and 6π‐Electrocyclization: Synthetic Scope and Application

Abstract

In this work, we report a domino reaction for access to highly functionalized imidazo[1,2‐a:5,4‐b′]dipyridines simply by stirring Boc2O in the presence of DMAP as a catalyst with readily prepared 3‐amino‐2‐(vinyl)imidazo[1,2‐a]pyridine. This methodology enables the synthesis of highly functionalized imidazodipyridines. The process proved to be compatible with a wide variety of substrates. The synthetic potential of this method was illustrated by performing a Suzuki‐Miyaura coupling on 4‐phenylimidazo‐dipyridin‐2‐ol derivatives. Screening of the biological activity of the newly generated compounds led to the identification of a new hit. Compound 7 l exhibits good antiproliferative activity in the submicromolar range against the human colon cancer cell line.magnified image

Mo-catalyzed cyclization of N-vinylindoles and skatoles: synthesis of dihydroindolo[1,2-c]-quinazolines and dihydroindolo[3,2-b]-indoles, and evaluation of their anticancer activities

“…Additionally, it was observed that the formation of the amine intermediate occurred in the presence of a wet solvent, as previously reported in our work. 31…”

“…Additionally, it was observed that the formation of the amine intermediate occurred in the presence of a wet solvent, as previously reported in our work. 31 Concerning the formation of DINI derivatives, the nitro compound 3k underwent conversion to the DINI derivative in a 72% yield within 6 h under the standard conditions (Scheme 5f). In the absence of Mo-catalyst, the reaction proceeded, albeit at a slower rate, requiring 48 hours for completion (Scheme 5g).…”

Recent Advances in Transition-Metal-Catalyzed Reactions of N-Tosylhydrazones

“…Alami, Hamze, and co-workers 62 reported a novel methodology for the synthesis of 3-aryl-1 H -pyrroloimidazo[1,2- a ]pyridines 87 by the cross-coupling of 3-nitro-2-(arylvinyl)imidazo[1,2- a ]pyridines 86 with N -tosylhydrazones 16 and followed by Cadogan reductive conditions (Scheme 31 ). The optimized one-pot reaction conditions were: step 1: N -tosylhydrazone 16 (1 mmol), 86 (1 mmol), catalyst Pd 2 dba 3 ·CHCl 3 (2.5 mol%), XPhos ligand (5 mol%), LiO t Bu base (2.2 mmol), in 1,4-dioxane solvent in a sealed tube under microwave irradiation at 110 °C for 30 mins; step 2: catalyst MoO 2 Cl 2 (dmf) 2 (10 mol%) and ligand PPh 3 (4 equiv) were added and the mixture was placed under MW irradiation at 135 °C for ~4 h; and step 3: (Boc) 2 O (1.3 mmol), DMAP (0.2 mmol), and Et 3 N base (3 mmol) were added, and the mixture was stirred at room temperature for 2 h. Electronic effects in the N -tosylhydrazones did not affect the yields of the reactions and various heterocyclic N -tosylhydrazone also gave the products in good yields.…”

Synthesis and DTF studies of novel aminoimidazodipyridines using 2-(3H-imidazo[4,5-b]pyridin-2-yl)acetonitrile as an efficient key precursor

“…Li et al 7 and Zhang et al 29 also reported on the utility of some imidazo[1,2-a]pyridin-3-amines as precursors for the synthesis of imidazo[1,2-a:5,4-b']dipyridines.…”