Pancreatic β-Cell O-GlcNAc Transferase Overexpression Increases Susceptibility to Metabolic Stressors in Female Mice.

The nutrient-sensor O-GlcNAc transferase (Ogt), the sole enzyme that adds an O-GlcNAc-modification onto proteins, plays a critical role for pancreatic β-cell survival and insulin secretion. We hypothesized that β-cell Ogt overexpression would confer protection from β-cell failure in response to metabolic stressors, such as high-fat diet (HFD) and streptozocin (STZ). Here, we generated a β-cell-specific Ogt in overexpressing (βOgtOE) mice, where a significant increase in Ogt protein level and O-GlcNAc-modification of proteins were observed in islets under a normal chow diet.

Electrochemically driven stereoselective approach to -1,2-diol derivatives from vinylarenes and DMF.

We have developed an electrochemically driven strategy for the stereoselective synthesis of protected -1,2-diols from vinylarenes with ,-dimethylformamide (DMF). The newly developed system obviates the need for transition metal catalysts or external oxidizing agents, thus providing an operationally simple and efficient route to an array of protected -1,2-diols in a single step. This reaction proceeds an electrooxidation of olefin, followed by a nucleophilic attack of DMF.

Palladium-Catalyzed Divergent Cyclopropanation by Regioselective Solvent-Driven C(sp )-H Bond Activation.

Reported is a tandem palladium-catalyzed Heck/regioselective C(sp )-H activation reaction for the divergent synthesis of spiro- and fused-cyclopropanated indolines from N-methallylated 2-bromoarylamides. The regioselectivity of the C-H bond activation in the σ-alkylPd intermediate is controlled by the solvent used. DFT calculations suggest that the polarity of solvent molecules could influence the transition-state energy, leading to a bifurcation of the C-H bond activation in the σ-alkylPd intermediate.

Transition metal-catalyzed site- and regio-divergent C-H bond functionalization.

Recent advances in transition metal-catalyzed C-H bond functionalization have profoundly impacted synthetic strategy. Since organic substrates typically contain several chemically distinct C-H bonds, controlling the regioselectivity of C-H bond functionalization is imperative to harness its full potential. Moreover, the ability to alter reaction pathways to selectively functionalize different C-H bonds in a substrate represents a greater opportunity and challenge.