Deraedt C, Pinaud N, Astruc D * Université de Bordeaux, Talence, France
Recyclable Catalytic Dendrimer Nanoreactor for Part-Per-Million Cu
I Catalysis of ‘Click’ Chemistry in Water.
J. Am. Chem. Soc. 2014;
136: 12092-12098
Key words
dendrimers - Huisgen cycloaddition - click chemistry - copper catalysis
Significance
The dendrimer 1 consists of water/organic compatible 27 triethyleneglycol (TEG) termini and a hydrophobic
core (for the preparation of 1, see: Chem. Commun. 2013, 49, 8169). [Hexabenzyltren-Cu]Br 3 and 1 promote the click reaction of benzyl azides and phenyl acetylenes in water to give
the corresponding triazoles in 89–96% yield. The catalyst 1-CuI
(4–200 ppm CuI), prepared from CuSO4·5H2O and NaAsc, also catalyzed the click reaction in 81–99% yield.
Comment
The TEG termini render the dendrimer 1 water-soluble, and the hydrophobic core allows solubilization of the hydrophobic
compound 3 and the substrates in water. The interaction between 1 and 3 was shown by selective 1H NMR shifts and a NOESY spectrum. The micelle nanoreactor 1 was recycled ten times (10th reuse: 2a, 91% yield). The click reaction was performed with 1 ppm 1-CuI
to give 2a in 50% yield, whose turnover number (TON) and turnover frequency (TOF) were 510000
and 21200 h—1, respectively.
