Gemfibrozil derivatives as activators of soluble guanylyl cyclase - A structure-activity study

Metal-Free Electrochemical C─H Chlorination of Terminal Alkanes

Although research on the activation of C─H bonds in alkanes has been ongoing for decades, there are still few strategies that are both highly selective and suitable for industrial production. Herein, we report a highly selective method for the chlorination of terminal C─H bonds in alkanes by combining electrochemistry and organocatalysis. The specific cavity size of organic molecular catalysts ensures high regioselectivity, while the use of inexpensive and readily reusable graphite felt electrodes, a simple electrochemical device, and mild conditions enables the reaction to maintain good efficiency even when applied to kilogram-scale production.

Nickel-Catalyzed Hydrocarboxylation of Terminal Unactivated Alkenes: Formation of Branched Carboxylic Acids and Competing Catalyst Deactivation from CO2 Reduction to CO

The reductive coupling of CO2 and alkenes represents a compelling strategy for the synthesis of carboxylic acids. In this study, we show that Ni(OAc)2 and 6,6'-Me2bpy (dmbpy) catalyzes hydrocarboxylation of terminal unactivated alkenes to afford the branched 2-methyl-substituted carboxylic acids. The nickel/dmbpy speciation in solution is elucidated through electrochemical and UV-visible and NMR spectroscopic methods. A catalyst deactivation process is identified, involving competitive reduction of CO2 to CO resulting in formation of an inactive Ni-CO complex. The Ni catalyst may be reactivated by oxidative treatment of the Ni-CO complex to release CO; however, the results highlight an important complication that can arise in Ni-catalyzed reductive coupling reactions with CO2.

1-Fluoro-1-sulfonyloxylation of Alkenes by Sterically and Electronically Tuned Hypervalent Iodine: Regression Analysis toward 1,1-Heterodifunctionalization

In the heterodifunctionalization of alkenes, 1,1-regioselectivity remains elusive in sharp contrast to 1,2-regioselectivity. Herein, the 1-fluoro-1-sulfonyloxylation of styrenes with Bu₄NBF₄ and sulfonic acids using a hypervalent iodine ArI(OAc)₂ is reported. Regression analysis of substituents on ArI(OAc)₂ suggested that their electron-withdrawing ability and steric factor influence the 1,1-heterodifunctionalization. We designed o-{2,4-(CF₃)₂C₆H₃}- and p-NO₂-substituted ArI(OAc)₂ by the regression analysis to achieve high selectivity.

Boryl Radicals Enabled a Three-Step Sequence to Assemble All-Carbon Quaternary Centers from Activated Trichloromethyl Groups

The construction of diversely substituted all-carbon quaternary centers has been a longstanding challenge in organic synthesis. Methods that add three alkyl substituents to a simple C(sp³) atom rely heavily on lengthy multiple processes, which usually involve several preactivation steps. Here, we describe a straightforward three-step sequence that uses a range of readily accessible activated trichloromethyl groups as the carbon source, the three C-Cl bonds of which are selectively functionalized to introduce three alkyl chains. In each step, only a single C-Cl bond was cleaved with the choice of an appropriate Lewis base-boryl radical as the promoter. A vast range of diversely substituted all-carbon quaternary centers could be accessed directly from these activated CCl₃ trichloromethyl groups or by simple derivatizations. The use of different alkene traps in each of the three steps enabled facile collections of a large library of products. The utility of this strategy was demonstrated by the synthesis of variants of two drug molecules, whose structures could be easily modulated by varying the alkene partner in each step. The results of kinetic and computational studies enabled the design of the three-step reaction and provided insights into the reaction mechanisms.

Bioengineered microglia-targeted exosomes facilitate Aβ clearance via enhancing activity of microglial lysosome for promoting cognitive recovery in Alzheimer's disease

Aggregation of amyloid in the form of senile plaques is currently considered to be one of the main mechanisms driving the development of Alzheimer's disease (AD). Therefore, targeting amyloid homeostasis is an important treatment strategy for AD. Microglia, as the main immune cells, contribute to endocytosis and clearance of amyloid beta (Aβ) via lysosome mediated degradation. As abnormal lysosomal function in microglia is associated with inefficient clearance of Aβ in AD, we designed bioengineered microglia-targeting exosomes to promote the targeted delivery of gemfibrozil (Gem) and restore the lysosomal activity of microglia in clearing Aβ aggregation. Our results suggested that mannose-modified exosomes laden with Gem (MExo-Gem) can not only bind with Aβ but also specifically target microglia through the interaction between Exo-delivered mannose and mannose receptors expressed in microglia, thus promoting Aβ entry into microglia. Exosomal Gem activated lysosomal activity and accelerated lysosome-mediated clearance of Aβ in microglia. Finally, MExo-Gem improved the learning and memory ability of AD model mice.