Simple inorganic base promoted C–N and C–C formation: synthesis of benzo[4,5]imidazo[1,2-a]pyridines as functional AIEgens used for detecting picric acid

Abstract

Metal-free catalyzed intermolecular tandem Michael addition/cyclization is developed for the synthesis of benzo[4,5]imidazo[1,2-a]pyridines from α-bromocinnamaldehyde. The RIM of the benzene ring at the C1-position makes them a new class of AIE molecules.

Simple inorganic base promoted polycyclic construction using mucohalic acid as a C3 synthon: synthesis and AIE probe application of benzo[4,5]imidazo[1,2-a]pyridines

“…Based on the abovementioned experimental results and the related literature, 17,18,26,37 a plausible reaction mechanistic pathway is proposed in Scheme 4. Initially, under the action of a base, the nucleophilic substitution reaction of 2 with muco-bromic acid 1a generates intermediate A .…”

“…It is well known that some benzo[4,5]imidazo[1,2- a ]pyridine compounds often have good fluorescence properties. 2,18,38 Herein, the C 1 position of the benzo[4,5]imidazo[1,2- a ]pyridine molecules is occupied by an N-heterocyclic ring, and the fluorescence properties of this framework are worth exploring. Therefore, we chose 4a as the representative compound to study the photophysical properties.…”

“…Lei 15 and Chen 16 reported the electrochemical oxidative annulation of N -phenylpyridin-2-amine as another green method (Scheme 1b). An inorganic base promoted intermolecular tandem Michael addition/cyclization using ynones (Scheme 1c) 17 or 2-bromocinnamaldehyde (Scheme 1d) 18 also can be an efficient strategy. 17,18 Although the abovementioned methods are useful for constructing benzo[4,5]imidazo[1,2- a ]pyridines, it is also meaningful to develop other effective and practical routes ( e.g.…”

“…An inorganic base promoted intermolecular tandem Michael addition/cyclization using ynones (Scheme 1c) 17 or 2-bromocinnamaldehyde (Scheme 1d) 18 also can be an efficient strategy. 17,18 Although the abovementioned methods are useful for constructing benzo[4,5]imidazo[1,2- a ]pyridines, it is also meaningful to develop other effective and practical routes ( e.g. , multicomponent reactions with step economy 19 ) for the green synthesis of this valuable chemical structure with multiple functions.…”

A NaHCO3 Promoted Three‐component Cyclization: Easy Access to Benzodisulfide Heterocycles

“…[29,31] Recently, Tang's group reported a decarboxylative multicomponent polymerization of p-phenylenediacetic acid, S 8 and aromatic diamines to convert S 8 into functional polythioamides with great structural diversity, large molecular weights and excellent yields. [32] Inspired by this, in the combination with our previous researches on the use of cheap inorganic bases in organic synthesis, [39,40] we utilized the decarboxylation of 2-halophenylacetic acids with a ring-forming reaction site in the presence of aromatic amines and S 8 as reactants to construct cyclic disulfide compounds. [25,32,[35][36][37][38] Because there are many kinds of aromatic amines as well, [41,42] our new three-component reaction can be used as a new method for the synthesis of benzene disulfide heterocyclic compounds with high efficiency, green and easily available starting materials.…”