α-Olefin Oligomerization Mediated by Group 4 Metallocene Catalysts: An Extreme Manifestation of the Multisite Nature of Methylaluminoxane.

Group 4 metallocenes are competent catalysts for the oligomerization of higher α-olefins. Among the many chemical and physical variables of importance in the process, one is the choice of cocatalyst (activator). The impact of various activators on the performance of a representative catalyst, (nBuCp)ZrCl, in the oligomerization of 1-octene was thoroughly investigated; in particular, the molecular weight distribution (MWD) of the oligomers was determined by means of high-resolution high performance liquid chromatography (HR-HPLC).

Synthesis of Natural and Sugar-Modified Nucleosides Using the Iodine/Triethylsilane System as -Glycosidation Promoter.

The reagent system based on the combined use of EtSiH/I acts as an efficient -glycosidation promoter for the synthesis of natural and sugar-modified nucleosides. An analysis of reaction stereoselectivity in the absence of C2-positioned stereodirecting groups revealed high selectivity with six-membered substrates, depending on the nucleophilic character of the nucleobase or based on anomerization reactions. The synthetic utility of the EtSiH/I-mediated -glycosidation reaction was highlighted by its use in the synthesis of the investigational drug apricitabine.

Lipid-associated macrophages reshape BAT cell identity in obesity.

Obesity and type 2 diabetes cause a loss in brown adipose tissue (BAT) activity, but the molecular mechanisms that drive BAT cell remodeling remain largely unexplored. Using a multilayered approach, we comprehensively mapped a reorganization in BAT cells. We uncovered a subset of macrophages as lipid-associated macrophages (LAMs), which were massively increased in genetic and dietary model of BAT expansion.

Frataxin deficiency shifts metabolism to promote reactive microglia via glucose catabolism.

Immunometabolism investigates the intricate relationship between the immune system and cellular metabolism. This study delves into the consequences of mitochondrial frataxin (FXN) depletion, the primary cause of Friedreich's ataxia (FRDA), a debilitating neurodegenerative condition characterized by impaired coordination and muscle control. By using single-cell RNA sequencing, we have identified distinct cellular clusters within the cerebellum of an FRDA mouse model, emphasizing a significant loss in the homeostatic response of microglial cells lacking FXN.

Cocatalyst effects in Hf-catalysed olefin polymerization: taking well-defined Al-alkyl borate salts into account.

Hafnium catalysts for olefin polymerization are often very sensitive to the nature of cocatalysts, especially if they contain "free" aluminium trialkyls. Herein, cocatalyst effects in Hf-catalysed propene polymerization are examined for four Hf catalysts belonging to the family of -symmetric (Hf-CS-Met) and -symmetric (Hf-C2-Met) metallocenes, as well as of octahedral (Hf-OOOO) and pentacoordinated (Hf-PyAm) "post-metallocenes". The performance of the recently developed {[iBu(PhNMe)Al](μ-H)}[B(CF)] (AlHAl) cocatalyst is compared with that of established systems like methylalumoxane, phenol-modified methylalumoxane and trityl borate/tri-iso-butylaluminium.