A novel and efficient synthesis of 2,4-disubstituted benzo[4,5]imidazo[1,2-a]pyrimidine skeletons is reported. Using 2-aminobenzimidazole and acetophenone as substrates, an I2-DMSO-mediated multicomponent reaction was described, which used a one-pot method to generate two C-N bonds and one C-C bond, yielding 25 substrates. Currently, such derivatives are used clinically for biorevealing, so we selected some of the compounds in this paper for photophysical characterization. Spectroscopic studies showed that the selected compounds have maximum absorption at 250 nm and maximum emission at 600 nm with quantum yields of 0.01-0.08.

A simple and efficient method for the synthesis of symmetric 2,3,5,6-tetrasubstituted pyridines from enaminones and triethyl orthoformate, catalyzed by pyridinium p-toluenesulfonate, has been established in which triethyl orthoformate was applied as a carbon source. The procedure was smoothly executed, culminating in the synthesis of symmetrical 2,3,5,6-tetrasubstituted pyridines with moderate to exceptional yields across a diverse array of substrates.

A simple and efficient method for the synthesis of 1,4-dihydropyridines from amines, N,N-dimethyl enaminone and N,N-dimethylaminoethanol in a four-component [2+1+2+1] annulation catalyzed by FeCl3 has been established, where N,N-dimethylaminoethanol was applied as a methine source. The procedure was executed smoothly, resulting in the synthesis of a wide range of 1,4-dihydropyridines with moderate to good yields. Additionally, these fluorophores exhibited good photophysical characteristics.

As a novel and environmentally friendly Brönsted acid, imidazole hydrochloride was used to promote the synthesis of 2,3-disubstituted-4(3H)-quinazolinone from o-aminobenzoic acid and DMF derivatives. The essence of this reaction is a multicomponent reaction, which constructs multiple chemical bonds between different components through the transamidation of imidazole hydrochloride. This protocol showed a wide range of functional group tolerance, and a series of quinazolinones were synthesized in low to moderate yields without metal catalysts, oxidants or other additives.

An efficient method for the construction of benzo[4,5]imidazo[1,2-a]pyrimidines using N,N-dimethylformamide as a one-carbon source and 2-aminobenzimidazoles and acetophenone as substrates through a one-pot, three-component cascade reaction is described. Spectra investigations indicated the fluorescent properties of selected products, exhibiting quantum yields 0.07-0.16 with maxima absorption at 266-294 nm and emission at 472-546 nm.

An efficient approach to 1H-perimidines synthesis from 1,8-diaminonaphthalene reactions with alpha-keto acids was described. The reaction was conducted under metal-free and additive-free conditions, using EtOH as a solvent. Moreover, this reaction can be conducted on a gram-scale, and shows a wide range of functional group tolerance.

An efficient and practical approach for the synthesis of tetrasubstituted pyridines has been described via the Imidazole hydrochloride-promoted reaction of enaminones with DMSO. This protocol showed good functional group tolerance, and a series of pyridines were synthesized in moderate to good yields without metal catalysts. A multi-gram scale reaction was also performed to ensure the scalability of the reaction. Notably, DMSO plays two vital roles: carbon source and solvent.

This article reports an efficient method for the synthesis of amide derivatives by the direct reactions of aromatic amines with 1,3-diketones promoted by pyridine hydrochloride under metal-free and solvent-free conditions. This transformation was accomplished by cleavage of CC bond in the presence of pyridine hydrochloride as additive, which excludes the use of transition-metals and harsh reaction conditions. This method has a broad substrate scope and good tolerance for sensitive functional groups. A multi-gram scale reaction is also performed to ensure the scalability of the reaction.

A green and efficient method for the synthesis of oxadiazaborole, dioxazaborinine, and oxadiazaborinine from the reactions of phenylboronic acid with amidoxime, α-hydroxyl oxime and α-hydroxyl hydrazone, respectively, is described. The reactions were performed under catalyst-free and mild conditions. All products can be rapidly purified by filtration and washing. In addition, a set of iminoboronates were prepared following a one-pot multicomponent reaction procedure using α-hydroxyl hydrazone, salicylaldehyde and boronic acid derivatives as starting materials and their photophysical properties were assessed. Then, cross-coupling reactions can be carried out smoothly on some target compounds, which may help develop new boron masking strategies.