A Novel Fluorescent Skeleton from Disubstituted Thiochromenones via Nickel-Catalyzed Cycloaddition of Sulfobenzoic Anhydrides with Alkynes

Discovery of C-3 isoxazole substituted thiochromone S,S-dioxide derivatives as potent and selective inhibitors for monoamine oxidase B (MAO-B)

Developing new scaffolds for highly potent and selective inhibitors of human Monoamine Oxidase B (hMAO-B) is a crucial objective in enhancing the efficacy and safety in the clinical treatment of neurodegenerative diseases. In this study, we have identified a series of C-3 isoxazole-substituted thiochromone S,S-dioxide derivatives that exhibit strong inhibitory activity against hMAO-B. The strategy of oxidizing thiochromone to thiochromone S,S-dioxide solves the key defect of extreme insolubility observed for thiochromone analogues. In addition, the sulfone group contributes extra hydrogen(H)-bonding interactions with Tyr435, which significantly increases the activity of thiochromone S,S-dioxide derivatives against hMAO-B. Furthermore, the presence of isoxazole group provides potential H-bonding interaction and electrostatic interaction with the residue of Tyr326, while the rigid aryl ring introduces a potential steric conflict with Phe208 of hMAO-A to improve both potency and selectivity. In our investigations, several compounds (9c, 10c, 10e, 10g, 10l and 10m) demonstrate remarkable single-digit nanomolar potency. These compounds exhibit favorable cytotoxicity profiles in both differentiated SH-SY5Y and HVSMC cells, without apparent cardiotoxic effects. Moreover, compounds 10e and 10h do not lead to an increase in ROS levels in differentiated SH-SY5Y cells, further demonstrating their potential as safe and effective hMAO-B inhibitors. These findings indicate that the C-3 isoxazole substituted thiochromone S,S-dioxide analogues are potential leading compounds for the development of selective inhibitors with high potency.

Innovative Synthetic Procedures for Luminogens Showing Aggregation-Induced Emission

As a consequence of their intrinsic advantageous properties, luminogens that show aggregation-induced emission (AIEgens) have received increasing global interest for a wide range of applications. Whereas general synthetic methods towards AIEgens largely rely on tedious procedures and limited reaction types, various innovative synthetic methods have now emerged as complementary, and even alternative, strategies. In this Review, we systematically highlight advancements made in metal-catalyzed functionalization and metal-free-promoted pathways for the construction of AIEgens over the past five years, and briefly illustrate new perspectives in this area. The development of innovative synthetic procedures will enable the facile synthesis of AIEgens with great structural diversity for multifunctional applications.

Transition-metal-free sulfonylations of methylthiolated alkynones to synthesize 3-sulfonylated thioflavones

A set of transition-metal-free NaI/TBHP-mediated sulfonylation cyclization reactions of methylthiolated alkynones with sulfonyl hydrazides was developed, by which various 3-sulfonylated thioflavones were prepared under mild reaction conditions.

Ni-Catalyzed stereoselective difunctionalization of alkynes

We summarize the progress of the nickel-catalyzed alkyne difunctionalization reaction for the synthesis of tri- and tetrasubstituted olefins, with an emphasis on the strategy and control of stereochemistry.