A Fischer-Type Ruthenium Carbene Complex as a Metathesis Catalyst for the Synthesis of Enol Ethers

3,6-Anhydrogalactal as a Single-Addition Monomer for Chain-End Functionalization of Metathesis Polymers

Controlling the structure and reactivity of the chain-end group is a central objective in modern polymer chemistry. Here we introduce 3,6-anhydrogalactal as a single-addition monomer that enables efficient and versatile chain-end functionalization of metathesis polymers. Readily synthesized from biomass-derived galactal, 3,6-anhydrogalactal exhibits excellent single-addition reactivity, allowing precise chain-end modifications even when introduced simultaneously with the propagating monomer. Theoretical calculations provide mechanistic insights into the unique reactivities governing its single-addition behavior. Its broad functional group compatibility facilitates diverse applications, including block copolymer synthesis, polymer-polymer coupling, and bioconjugation, demonstrating significant potential for advancing polymer materials and bioconjugation strategies.

Self-Assembly and In Situ Quaternization of Triblock Bottlebrush Block Copolymers via Organized Spontaneous Emulsification for Effective Loading of DNA

Microspheres bearing large pores are useful in the capture and separation of biomolecules. However, pore size is typically poorly controlled, leading to disordered porous structures with limited performances. Herein, ordered porous spheres with a layer of cations on the internal surface of the nanopores are facilely fabricated in a single step for effective loading of DNA bearing negative charges. Triblock bottlebrush copolymers (BBCPs), (polynorbornene-g-polystyrene)-b-(polynorbornene-g-polyethylene oxide)-b-(polynorbornene-g-bromoethane) (PNPS-b-PNPEO-b-PNBr), are designed and synthesized for fabrication of the positively charged porous spheres through self-assembly and in situ quaternization during an organized spontaneous emulsification (OSE) process. Pore diameter as well as charge density increase with the increase of PNBr content, resulting in a significant increase of loading density from 4.79 to 22.5 ng µg-1 within the spheres. This work provides a general strategy for efficient loading and encapsulation of DNA, which may be extended to a variety of different areas for different real applications.

Late-stage Modification of Cage Diones by Tandem Metathesis

Herein, we report the application of tandem ring-opening cross-metathesis (ROCM) and tandem ring-opening cross-metathesis followed by cross-metathesis (ROCM/CM) in highly strained diastereomeric heptacyclic cage diones (HCCD's) catalyzed by ruthenium catalysts. These caged diastereomeric compounds have a high degree of ring strain as well as steric congestion. Therefore, the present work related to ROCM is unique and intricate as compared to simple norbornene derivatives. It is useful to prepare new hexacyclic cage derivatives suitable for high-energy density materials. The synthetic strategy of starting cage compounds features the Diels-Alder reaction, and [2+2] photocycloaddition as key steps.