A Bioactive Synthetic Outer-Core Oligosaccharide Derived from a Klebsiella pneumonia Lipopolysaccharide for Bacteria Recognition.

There is an urgent need for new treatment options for carbapenem-resistant Klebsiella pneumoniae (K. pneumoniae), which is a common cause of life-threatening hospital- and community-acquired infections. Prophylactic or therapeutic vaccination may offer an approach to control these infections, however, none has yet been approved for human use.

Synthesis of Triphenylenes Starting from 2-Iodobiphenyls and Iodobenzenes via Palladium-Catalyzed Dual C-H Activation and Double C-C Bond Formation.

A novel and facile approach for the synthesis of triphenylenes has been developed via palladium-catalyzed coupling of 2-iodobiphenyls and iodobenzenes. The reaction involves dual palladium-catalyzed C-H activations and double palladium-catalyzed C-C bond formations. A range of unsymmetrically functionalized triphenylenes can be synthesized with the reaction.

Synthesis of 2-substituted tetraphenylenes via transition-metal-catalyzed derivatization of tetraphenylene.

A new strategy for the synthesis of 2-substituted tetraphenylenes through a transition-metal-catalyzed derivatization has been developed. Three types of functionalities, including OAc, X (Cl, Br, I) and carbonyl, were introduced onto tetraphenylene, which allows the easy access to a variety of monosubstituted tetraphenylenes. These reactions could accelerate research on the properties and application of tetraphenylene derivatives.

Synthesis of Fluorenes Starting from 2-Iodobiphenyls and CH2Br2 through Palladium-Catalyzed Dual C-C Bond Formation.

A facile and efficient approach is developed for the synthesis of fluorene and its derivatives starting from 2-iodobiphenyls and CH2Br2. A range of fluorene derivatives can be synthesized under relatively mild conditions. The reaction proceeds via a tandem palladium-catalyzed dual C-C bond formation sequence through the key dibenzopalladacyclopentadiene intermediates, which are obtained from 2-iodobiphenyls through palladium-catalyzed C-H activation.

Amino acid-promoted C-H alkylation with alkylboronic acids using a removable directing group.

Palladium-catalyzed C-H alkylation reaction with alkylboronic acids has successfully been developed using a removable pyridyldiisopropylsilyl directing group. The amino acid played a crucial role as a ligand in the reaction. The alkylation protocol is also applicable to the coupling of C(sp(3))-H bonds with alkylboronic acids.

Sequential Difunctionalization of 2-Iodobiphenyls by Exploiting the Reactivities of a Palladacycle and an Acyclic Arylpalladium Species.

A novel sequential difunctionalization reaction of 2-iodobiphenyl has been developed by exploiting the distinct reactivities of a palladacycle and an acyclic arylpalladium species. In this tandem reaction, an in situ formed dibenzopalladacyclopentadiene reacts selectively with an alkyl halide, after which the thus formed acyclic arylpalladium species selectively undergoes a Heck reaction with an alkene. This work demonstrates the strong relationship between the coordination mode of a transition metal complex and its reactivity, which could shed light on the mechanisms of other transition-metal-catalyzed reactions and offer the opportunity to develop other synthetically enabling organic transformations.

An Approach to Tetraphenylenes via Pd-Catalyzed C-H Functionalization.

Tetraphenylenes not only are theoretically and experimentally interesting but also have potential applications in a variety of fields such as materials science, supramolecular chemistry, and asymmetric catalysis. A facile and efficient approach is reported for the syntheis of tetraphenylene and its derivatives from 2-iodobiphenyls via Pd-catalyzed C-H activation. A range of substituted tetraphenylenes can be synthesized using this method, and the reaction can be performed on gram scale with relatively high efficiency, demonstrating its practical utility.