Nickel-Catalyzed Enantioselective Synthesis of Dienyl Sulfoxide.

Sulfoxides are widely used in the pharmaceutical industry and as ligands in asymmetric catalysis. However, the efficient asymmetric synthesis of this structural motif remains limited. In this study, we disclosed a Ni-catalyzed enantioconvergent reaction that utilizes both racemic allenyl carbonates and ß-sulfinyl esters. Our method employs cheap and more sustainable Ni(II) as a precatalyst and successfully overcomes the challenging poisoning effect and instability of sulfenate generated in situ. This enables the synthesis of a series of dienyl sulfoxides with enantioselectivity of up to 98 % ee. The product exhibits tremendous potential in various applications, including diastereoselective Diels-Alder reactions, coordination with transition metals, and incorporation into medicinal compounds, among others. Using a combination of experimental and computational methods, we have uncovered an interesting associated outersphere mechanism that contrasts with conventional mechanisms commonly observed in asymmetric transition metal catalysis.

[Research progress in pathogenesis and traditional Chinese medicines treatment of ischemic stroke-related headache].

Headache is a common clinical complication of ischemic stroke. As a precursor of stroke, headache occurs repeatedly in the convalescent period of ischemic stroke, leading to secondary stroke and seriously hindering patients' rehabilitation. Currently, it is believed that the pathogenesis of ischemic stroke-related headache is associated with the abnormal release of vasoactive substances, high platelet aggregation, and stimulation of intracranial pain-sensitive structures. The active ingredients in traditional Chinese medicines(TCM) with the effects of activating blood to resolve stasis and clearing heat to release exterior can protect brain tissue and relieve headache by reducing the release of inflammatory cytokines, alleviating antioxidant stress, inhibiting neuronal apoptosis and so on. This paper introduces the research progress in the potential mechanism and TCM treatment of ischemic stroke-related headache, aiming to provide reference for further research and drug development of this complication.

Facile surface immobilization of ATRP initiators on colloidal polymers for grafting brushes and application to colloidal crystals.

Bromo-initiators for atom transfer radical polymerization (ATRP) were successfully immobilized on the surfaces of cross-linked poly(methyl methacrylate) (PMMA) spheres by soap-free emulsion polymerization using CBr(4) as the chain transfer agent. Subsequent surface-initiated ATRP (SI-ATRP) afforded a layer of PMMA brushes covalently attached to the sphere surfaces. Colloidal crystal films of these monodisperse spheres were then studied to identify the relationship between variation in particle diameter and the optical properties. The particle diameters were controlled by varying the feed monomer proportions in soap-free emulsion polymerization and the thickness of the grafted brush layer. It was found that the particle diameter could successfully be controlled to obtain crystal films that produce a variety of brilliant colors in the visible region. The results of this study can provide useful information for facile preparation of surface-immobilized ATRP initiators on colloidal polymers and can be employed for grafting polymer brushes.