C . D E R A E D T , N . P I N A U D , D . A S T R U C * ( U N I V E R S I T É D E B O R D E A U X , TA L E N C E , F R A N C E )
Recyclable Catalytic Dendrimer Nanoreactor for Part-Per-Million
J. Am. Chem. Soc. 2014, 136, 12092–12098.
CuI
Catalysis of ‘Click’ Chemistry in Water
Ca t e g o r y
Polymer-Supported
Synthesis
Dendritic Copper Catalysts for Homogeneous
Click Chemistry in Water
Ke y w o rd s
dendrimers
Huisgen
cycloaddition
click chemistry
copper catalysis
Cu
Cu
CuI
CuII
CuII
II
H2O, 25 °C
NaAsc
Cu
CuI
Cu
I
CuI
CuI
I
CuII CuII
CuII
CuI
catalyst 1-CuI
TEG
Me
Si
=
Me
O
N
TEG
N N
TEG
TEG = trimethyleneglycol
+
R2
N
conditions
N
Ph
R2
N
1
N
R
R1
2
N
Ph
Cu
N
Ph
Ph
Br–
Ph
Selected examples:
N
N
N
2a R1 = H, R2 = Ph
conditions A: 91% yield
conditions B: 99% yield (4 ppm CuI)
2b R1 = H, R2 = TMS
conditions A: 89% yield
conditions C: 81% yield (20 ppm CuI)
N
N
2c R1 = Me, R2 = Ph
conditions A: 90% yield
conditions B: 89% yield (20 ppm CuI)
[hexabenzyltren-Cu]Br 3
tren = triaminoethylamine
TMS
N
N
N
N
Ph
conditions A: dendrimer 1 (1 mol%), [hexabenzyltren-Cu]Br 3 (0.1 mol%), H2O, 25 °C, 3 h
conditions B: catalyst 1-CuI (4–50 ppm CuI), H2O, 30 °C, 24 h
conditions C: catalyst 1-CuI (4–50 ppm CuI), H2O, 35 °C, 24 h
N
month
CuI
CuI
pre-catalyst 1-CuII
dendrimer 1
N3
of the
H2O, 25 °C
This document was downloaded for personal use only. Unauthorized distribution is strictly prohibited.
CuII
CuSO4·5H2O
CuII
II
NC
N
N
Br
N
N
N
N
2d R1 = CN, R2 = Ph
conditions A: 90% yield
conditions B: 90% yield (50 ppm CuI)
2e R1 = Br, R2 = Ph
conditions A: 96% yield
conditions C: 89% yield (50 ppm CuI)
Significance: The dendrimer 1 consists of water/
Comment: The TEG termini render the dendrimer
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.
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.
SYNFACTS Contributors: Yasuhiro Uozumi, Yoichi M. A. Yamada, Rikako Ishii
Synfacts 012014, 10(12), 1331 Published online: 18.11.20141861-19581861-194X
DOI: 10.1055/s-0034-1379574; Reg-No.: Y13214SF
©
GN
eogr·ehm
T
iew
gtaV
rS
Y
uetagleork
2014 © THIEME STUTTGART • NEW YORK
1331