Diversified Synthesis of Chiral Fluorinated Cyclobutane Derivatives Enabled by Regio- and Enantioselective Hydroboration.

The diversified synthesis of chiral fluorinated cyclobutane derivatives has remained a difficult task in synthetic chemistry. Herein, we present an approach for asymmetric hydroboration and formal hydrodefluorination of gem-difluorinated cyclobutenes through rhodium catalysis, providing chiral gem-difluorinated α-boryl cyclobutanes and monofluorinated cyclobutenes with excellent regio- and enantioselectivity, respectively. The key to the success of the two transformations relies on an efficient, mild and highly selective rhodium-catalyzed asymmetric hydroboration with HBPin (pinacolborane), in which the subsequent addition of a base, and a catalytic amount of palladium in some cases, results in the formation of formal hydrodefluorination products with the four-membered ring retained. The obtained chiral gem-difluorinated α-boryl cyclobutanes are versatile building blocks that provide a platform for the synthesis of enantioenriched fluorinated cyclobutane derivatives to a great diversity.

Copper-Catalyzed Ring-Opening Defluoroborylation of gem-Difluorinated Cyclobutenes: A General Route to Bifunctional 1,3-Dienes and Their Applications.

The exploration of the reactivity of gem-difluorinated small-size rings has continuously drawn attention in recent years but is limited to three-membered carbocycles. Herein we report a copper-catalyzed reaction of gem-fluorinated cyclobutenes with bis(pinacolato)diboron (B2pin2). A sequence of defluoroborylation and a ring-opening process produces B,F-bifunctional 1,3-dienes in a stereoselective manner. The transformation together with the efficient downstream coupling of the boronate and the fluoride moieties collectively constitutes a modular route to highly functionalized and stereocontrolled 1,3-dienes.

A 3D printed wound cooling system incorporated with injectable, adsorbable, swellable and broad spectrum antibacterial scaffolds for rapid hematischesis processing.

Uncontrolled hemorrhage remains a leading cause of early death after trauma, and contamination further challenges the wounded. In the present study, silver nanocluster (or silver nanoparticle) decorated rapidly swellable hemostatic scaffolds (AgNCs/RSHs and AgNPs/RSHs) were prepared. A 3D printed injectable wound cooling hemostatic (IWCH) system was accordingly designed and implemented to realize the relative rapid hemostasis operation. The obtained AgNCs/RSHs and AgNPs/RSHs exhibited excellent biocompatibility and broad-spectrum antibacterial properties including drug resistant strains. In a rabbit femoral vascular injury model, bleeding could be instantly stopped in 10 seconds by using IWCHs. The present study provided a new insight into the development of rapid hemostatic biomaterials to realize a quick, precise and simplified hemostasis operation in less time and with less bleeding.