Tsuji–Trost N-Allylation with a Cellulose–Palladium Catalyst
deactivating groups were employed to study the reaction
scope. (E)-3-(4-Methoxyphenyl)allyl acetate participated in
the reaction with morpholine to give allylated product 5h
in 86 % yield. (E)-3-(p-Tolyl)allyl acetate reacted efficiently
with morpholine to afford 5j in 88 % yield.
Experimental Section
General Procedure: A mixture of allyl acetate (1.0 mmol), amine
(1.2 mmol), cellulose–Pd (50 mg), and potassium carbonate
(2.0 mmol) in anhydrous DMF (3 mL) was heated at 110 °C under
a N2 atmosphere for 15 h. Upon completion of the reaction, as
indicated by TLC, the reaction mixture was diluted with water and
centrifuged/filtered to separate the catalyst. The decanted liquid
(E)-3-(4-Chlorophenyl)allyl acetate reacted smoothly
with 1-methylpiperazine to give 5k in 92% yield. Unsubsti-
tuted allyl acetate also participated efficiently in the reac- was extracted with ethyl acetate (3ϫ 10 mL); the organic layer was
dried with anhydrous sodium sulfate and evaporated under reduced
pressure to afford the crude product. The crude product was puri-
fied by passing through a silica gel column (ethyl acetate/hexane).
tion with piperidine and morpholine to yield 5g and 5i in
96 and 93% yield, respectively, which indicates that the na-
ture of the substituent on the allyl acetate does not have a
significant effect on the reaction. A branched cinnamyl Supporting Information (see footnote on the first page of this arti-
cle): Experimental procedures, 1H NMR and 13C NMR spectra,
and MS data.
acetate, 1-phenylallyl acetate, also provided linear trans-
product 5a (Table 2, entry 12), which supports the mecha-
nism that describes the intermediacy of a η3-allyl–Pd com-
plex as the key intermediate in the reaction. The high yields
of the products with various substrates indicate the broad
Acknowledgments
scope of the optimized protocol. In the case of primary
amines (Table 2, entries 4–6), trace amounts of diallylation gram at the National Risk Management Research Laboratory ad-
B. R. V. and A. S. are supported by the Postgraduate Research Pro-
ministered by the Oak Ridge Institute for Science and Education
through an interagency agreement between the U.S. Department of
Energy and the U.S. Environmental Protection Agency.
products were found.
The active role of palladium in the catalytic cycle of the
reaction was established by control experiments. No prod-
uct formation occurred in the absence of a catalyst. The
same reaction, when carried out separately in the presence
of cellulose, was fruitless, but the cellulose–Pd catalyst gave
good product yields, and this indicates that the reaction is
catalyzed only by palladium.
Upon completion of the reaction, the catalyst was sepa-
rated by filtration or centrifugation and washed with acet-
one followed by drying in a vacuum oven. The recovered
catalyst was used over three consecutive cycles of the reac-
tion (Table S1, Supporting Information). The amount of
palladium on the cellulose was analyzed after recovering
the catalyst after the fifth reaction cycle. ICP-AES analysis
showed almost the same palladium concentration on the
catalyst; the absence of palladium metal in the reaction sol-
vent indicated that no metal leached into the reaction mix-
ture. The hydroxy groups on cellulose may provide efficient
binding sites that coordinate with palladium, which would
thus enable efficient catalyst recycling and prevent metal
leaching.
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Conclusions
A simple and easy procedure for the N-allylation of
amines was developed by using a biodegradable and easily
recyclable heterogeneous cellulose-supported Pd catalyst in
DMF under conventional heating. This protocol is appli-
cable to aliphatic and benzylamines and substituted and un-
substituted allyl acetates. Highlights of this protocol include
a ligand-free reaction, simple workup, and catalyst recovery
and reuse.
Received: September 18, 2012
Published Online: October 30, 2012
Eur. J. Org. Chem. 2012, 6707–6709
© 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjoc.org
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