Copper-granule-catalyzed microwave-assisted click synthesis of polyphenol dendrimers

Choon Young Lee, Rich Held, Ajit Sharma, Rom Baral, Cyprien Nanah, Dan Dumas, Shannon Jenkins, Samik Upadhaya, Wenjun Du

Research output: Contribution to journalArticlepeer-review

23 Scopus citations

Abstract

Syringaldehyde- and vanillin-based antioxidant dendrimers were synthesized via microwave-assisted alkyne-azide 1,3-dipolar cycloaddition using copper granules as a catalyst. The use of Cu(I) as a catalyst resulted in copper contaminated dendrimers. To produce copper-free antioxidant dendrimers for biological applications, Cu(I) was substituted with copper granules. Copper granules were ineffective at both room temperature and under reflux conditions (<5% yield). However, they were an excellent catalyst when dendrimer synthesis was performed under microwave irradiation, giving yields up to 94% within 8 h. ICP-mass analysis of the antioxidant dendrimers obtained with this method showed virtually no copper contamination (9 ppm), which was the same as the background level. The synthesized antioxidants, free from copper contamination, demonstrated potent radical scavenging with IC50 values of less than 3 μM in the 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay. In comparison, dendrimers synthesized from Cu(I)-catalyzed click chemistry showed a high level of copper contamination (4800 ppm) and no detectable antioxidant activity.

Original languageEnglish
Pages (from-to)11221-11228
Number of pages8
JournalJournal of Organic Chemistry
Volume78
Issue number22
DOIs
StatePublished - Nov 15 2013

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