UCLA researchers in the Department of Chemistry & Biochemistry have developed a novel method for the conversion of Dewar heterocycles to versatile monomers with capacity for post-polymerization chemistry.
BACKGROUND:
Post-polymerization modifications are crucial in the development of synthetic materials for electronic, biomedical, and feedstock industries. Aromatic compounds are widely used as synthetic chemical precursors due to their ease of accessibility and great abundance in nature. However, aromatic molecules often have limited reactivity given their resonance energy stability. Current strategies for post-polymerization modification suffer from low conversion and yields as well as the use of hard-to-remove metal catalysts. Novel methods that reveal highly reactive functionality after polymerization would allow for post-polymerization modification and generation of a densely-functionalized foundation for synthesis reactions and polymeric materials.
INNOVATION:
Scientists at UCLA have developed methods to utilize Dewar heterocycles as precursors to unique ring opening metathesis polymerization (ROMP) monomers using Grubbs catalysts. This ROMP chemistry is capable of diverse N-functionalization, as well as unprotected lactams, which may be subject to post-polymerization modification for use in biomedical applications. Alternatively, Dewar pyrones may be converted to β-chloroester polymers, which are then modified to ester-substituted poly(acetylene) possessing high solubility in various organic solvents. These polymers may therefore also be suitable for conductance and electronic applications. This method is capable of accessing novel polymer backbones that have not been previously isolated due to the difficulties in generating the necessary monomer and provide solutions for medical devices, electronic materials and other functionalized polymer materials.
POTENTIAL APPLICATIONS:
•Synthesis of ring opening metathesis polymerization (ROMP) monomers
•Generation of water-soluble β-amino acid-type polymers for biomedical applications
•Generation of azetidine moieties and other strained azacyclic rings in polymer backbone
•Generation of substituted poly(acetylene) derivatives that are highly soluble
ADVANTAGES:
•Dearomatized photoproducts readily engage in ROMP chemistry using Grubbs catalysts
•ROMP chemistry is tolerable of various N-functionalization, and unprotected lactams
•Bicyclic photoproducts are very reactive given the strained nature of their structures
•Cheap and abundant precursors
•Cost-effective transformation
DEVELOPMENT-TO-DATE:
This synthesis method has been validated by the synthesis of water-soluble β-amino acid type polymers and soluble poly(acetylene) derivatives.