A straightforward and novel controllable siteselective construction of 2-and 4-substituted pyrimido[1,2b]indazole from 3-aminoindazoles and ynals has been developed. The high regioselectivity of this reaction could be easily switched by converting different catalytic systems. In this way, a series of 2and 4-substituted pyrimido[1,2-b]indazole derivatives were obtained in moderate to good yields. In addition, the photophysical properties of compound 3a prepared by the present method were discussed.
The spontaneous accumulating nature and undesirable catalytic activity of nanosized noble-metal nanoparticle-based nanozymes significantly limit their applications in the bioanalytical field. Herein, by combining surface modification and nonprecious metal doping strategies, polydopamine-dressed PdCu alloy (PDA-PdCu) nanozymes with nanochain networks are successfully prepared through a facile one-pot NaBH 4 reduction method. It is found that dopamine can shorten the gel formation time and Cu is indispensable for the formation of jelly-like PDA-PdCu samples with chain-like structures. Notably, benefiting from the improved Pd(0)/Pd(II) ratio, the enhanced substrate affinity, and the increased active surface area, the synthesized PDA-PdCu samples exhibit considerably enhanced oxidase mimetic activity compared to PDA-Pd and PdCu nanozymes. By making full use of the enhanced oxidase-like activity of PDA-PdCu and using 3,3′,5,5′-tetramethylbenzidine as a chromogenic substrate, a sensitive and straightforward colorimetric biosensing strategy for ascorbic acid (AA)-related bioenzyme activity, including the AA-generating alkaline phosphatase (ALP) and α-glucosidase (α-Glu) as well as the AA-consuming ascorbic acid oxidase (AA-ox), is elaborately developed. This work not only elucidates that the performance of the nanozyme can be modulated simultaneously by composition and surface modification but also provides a new versatile colorimetric sensing platform for AA-related bioenzymes.
An efficient and straightforward metal-free regioselective C−H dithiocarbamation of indolizines with tetraalkylthiuram disulfide has been described. A series of indolizines-dithiocarbamates derivatives were easily accessed in moderate to good yields with...
A novel and attractive aerobic oxidative hydroxysulfonyloxylation of gem-difluoroalkenes with sodium sulfinate via free radical addition has been developed. In addition, successive defluorination-decarboxylation sulfonylation of gem-difluoroalkenes in the presence of...
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.