A facile and metal-free one-pot protocol for the synthesis of fused imidazopyridine scaffolds has been developed. This novel protocol combines the Groebke–Blackburn–Bienaymé reaction (GBBR) with a sequential TBAB-mediated cyclization cascade. Biological evaluation demonstrated that compound 6a inhibits human prostate cancer cell DU-145 proliferation with an IC50 of 1.6 μM. The molecular mechanism study indicates that 6a significantly suppresses the oncogenic Erk kinase phosphorylation at 3 μM.

A transition-metal free, high yielding and efficient three-component reaction was designed and incorporated into two sequential oxidation and cyclization reaction cascades in one-pot with the assistance of microwave irradiation. A chemical collection of functionalized 3-substituted imidazopyridines was prepared by means of the mild reaction and simple operational procedure. The reaction has a broad tolerance for a variety of substituted carbonyl aldehydes, anilines and 2phenyl-imidazo[1,2-a]pyridines. Screening in several cancer cell lines was conducted. Compound 9 i exhibited good potency against HeLa cell lines and this work validated the feasibility of the methodology for generating bioactive compounds.

We report an intramolecular hydrogen bond-promoted Ugi cascade reaction for solvent-free synthesis of 2,5-diketopiperazines. Compounds (±) 5c and (±) 5e displayed potent antitumor activity against acute myeloid leukaemia and prostate cancer cell lines, respectively.

Correction for ‘An intramolecular hydrogen bond-promoted “green” Ugi cascade reaction for the synthesis of 2,5-diketopiperazines with anticancer activity’ by Jie Li et al., RSC Adv., 2022, 12, 33175–33179, https://doi.org/10.1039/D2RA04958A.