An efficient and convenient method of C5-selective halogenation of quinoline derivatives was developed.

23-Hydroxybetulinic acid (23-HBA) is a complex lupane triterpenoid, which has attracted increasing attention as an anticancer agent. However, its detailed mechanism of anticancer action remains elusive so far. To reveal its anticancer mode of action, a series of fluorescent 23-HBA derivatives conjugated with coumarin dyes were designed, synthesized, and evaluated for their antiproliferative activities. Subcellular localization and uptake profile studies of representative fluorescent 23-HBA probe 26c were performed in B16F10 cells, and the results suggested that probe 26c was rapidly taken up into B10F10 cells in a dose-dependent manner and mitochondrion was the main site of its accumulation. Further mode of action studies implied that the mitochondrial pathway was involved in 23-HBA-mediated apoptosis. Together, our results provided new clues for revealing the molecular mechanism of natural product 23-HBA for its further development into an antitumor agent.

A scalable catalytic synthesis method using commodity chemicals for constructing diaryl thioethers directly from sodium arylsulfinates and iodoarenes is reported in this study. In the presence of CuO or other copper salts such as Cu(OAc)2 as well as palladium catalysts, DABCO demonstrated to be essential to promote this transformation. Various iodoarenes and aryl sulfinates were examined and demonstrated the viability of this method. The mechanistic study showed that radical reactions occurred, while DABCO N‐oxide radical can be observed by mass spectrometry. A plausible catalytic mechanism involving DABCO is also discussed, suggesting synergistic reduction of sulfinate by Cu(II) and DABCO is the key step of this coupling reaction.

N-(Pyridin-2-yl)amides and 3-bromoimidazo[1,2-a]pyridines were synthesized respectively from abromoketones and 2-aminopyridine under different reaction conditions. N-(Pyridin-2-yl)amides were formed in toluene via C-C bond cleavage promoted by I 2 and TBHP and the reaction conditions were mild and metal-free. Whereas 3-bromoimidazopyridines were obtained in ethyl acetate via one-pot tandem cyclization/bromination when only TBHP was added, the cyclization to form imidazopyridines was promoted by the further bromination, no base was needed, and the versatile 3bromoimidazopyridines could be further transferred to other skeletons.Scheme 1 Recent methods for the construction of pyridyl-amides and halosubstituted imidazopyridines.34672 | RSC Adv., 2019,9,[34671][34672][34673][34674][34675][34676] This journal is Scheme 6 Proposed reaction mechanism.This journal is