Enantioselective Nickel-Catalyzed C(sp3 )-H Activation of Formamides.

Enantioselective Ni-catalyzed C(sp3 )-H bond activation remains an elusive challenge. Herein, we used phosphine oxide-ligated Ni-Al bimetallic catalyst to realize enantioselective Ni-catalyzed aliphatic C(sp3 )-H activation of formamides, providing a series of chiral N-containing heterocycles in 40-95 % yield and 70-95 % ee.

Enantioselective Twofold C-H Annulation of Formamides and Alkynes without Built-in Chelating Groups.

Twofold C-H annulation of readily available formamides and alkynes without built-in chelating groups was achieved. Ni-Al bimetallic catalysis enabled by a bulky BINOL-derived chiral secondary phosphine oxide (SPO) ligand proved to be critical for high reactivity and high selectivity. This reaction uses readily available formamides as starting materials and provides a concise synthetic pathway to a broad range of chiral ferrocenes in 40-98 % yield and 93-99 % ee.

Enantioselective Ni-Al Bimetallic Catalyzed exo-Selective C-H Cyclization of Imidazoles with Alkenes.

A Ni-Al bimetallic catalyzed enantioselective C-H exo-selective cyclization of imidazoles with alkenes has been developed. A series of bi- or polycyclic imidazoles with ß-stereocenter were obtained in up to 98% yield and >99% ee. The bifunctional SPO ligand-promoted bimetallic catalysis proved to be critical to this challenging stereocontrol.

Ligand-Accelerated Direct C-H Arylation of BINOL: A Rapid One-Step Synthesis of Racemic 3,3'-Diaryl BINOLs.

An ortho-selective rhodium-catalyzed direct C-H arylation of 1,1'-bi-2-naphthol (BINOL), to deliver the widely used but not easily available 3,3'-diaryl BINOL, has been developed. This highly efficient one-step synthetic approach is the shortest route to date and is greatly facilitated by the newly developed ligand system comprising tBu2 PCl, Ph2 -cod, and Cy3 P⋅HBF4 . In addition, the same procedure can facilitate the challenging syntheses of 3-bulkyaryl BINOLs in good to excellent yields.

Iron-Catalyzed Regioselective Transfer Hydrogenative Couplings of Unactivated Aldehydes with Simple Alkenes.

An FeBr3 -catalyzed reductive coupling of various aldehydes with alkenes that proceeds through a direct hydride transfer pathway has been developed. With (i) PrOH as the hydrogen donor under mild conditions, previously challenging coupling reactions of unactivated alkyl and aryl aldehydes with simple alkenes, such as styrene derivatives and α-olefins, proceeded smoothly to furnish a diverse range of functionalized alcohols with complete linear regioselectivity.

Ligand-Enabled Ni-Al Bimetallic Catalysis for Nonchelated Dual C-H Annulation of Arylformamides and Alkynes.

A bifunctional secondary phosphine oxide (SPO) ligand-controlled method was developed for Ni-Al-catalyzed nonchelated dual C-H annulation of arylformamides with alkynes, providing a series of substituted amide-containing heterocycles in ≤97% yield. The SPO-bound bimetallic catalysis proved to be critical to the reaction efficiency.

[The effects of amylin on the islet beta-cells voltage-gated L-calcium channels in rats].

OBJECTIVE: To observe the effect of amylin on the islet beta-cells voltage-gated L-calcium channels in rats. METHOD: Patch clamp technique was employed in the observation of the features and changes of electric current of islet beta-cells voltage-gated L-calcium channels before and after using amylin. RESULTS: In the glucose environment of 5.5 mmol/L, the electric current of rat islet beta-cells voltage-gated L-calcium channels was activated at -40 mV and reached the peak at about +20 mV, with a peak value of about -120 pA and the insulin secretion level was (0.76 +/- 0.12) microg/L. Under the stimulation of glucose of 16.7 mmol/L, the peak current voltage moved to the left and increased up to - 140 pA and the level of insulin secretion measured (1.78 +/- 0.13) microg/L. Hatch islet beta-cells in amylin at the concentrations of 0.5, 1.0, 5.0 and 10.0 micromol/L, respectively. It was observed that in the 0.5 micromol/L and 1.0 micromol/L groups, there was no remarkable change in the peak potential activation voltage, current, and insulin secretion volume in comparison with the control group. However, in the environment of 5.5 mmol/L glucose, the increase of activation voltage of the 5.0 and 10.0 micromol/L groups was - 30 mV, with the peak current reduced to approximately -80 pA and -60 pA and the insulin secretion decreased to (0.49 +/- 0.11) microg/L and (0.36 +/- 0.12) microg/L respectively. Under the concentration of 16.7 mmol/L glucose, the activation voltage increased from -40 mV up to -30 mV and the peak current reduced to -80 pA and -40 pA. In the meantime, the insulin secretion decreased respectively to (1.20 +/- 0.13) microg/L and (0.89 +/- 0.14) microg/L, which is of significance. CONCLUSION: The secretion of insulin is synchronized with the opening of the islet beta-cells voltage-gated L-calcium channels at the stimulation of glucose. The amylin inhibition of the insulin secretion is also synchronized with the opening of islet beta-cells voltage-gated L-calcium channels and it's in a positive concentration-dependent manner.