ORGANIC
LETTERS
2004
Vol. 6, No. 6
985-987
Microwave-Assisted Amination from Aryl
Triflates without Base and Catalyst
Gang Xu and Yan-Guang Wang*
Department of Chemistry, Zhejiang UniVersity, Hangzhou 310027, P. R. China
Received January 6, 2004
ABSTRACT
Aryl triflates are effectively converted to the corresponding anilines under microwave irradiation in 1-methyl-2-pyridone (NMP) without base
and catalyst. Aryl triflates substituted with both electron-poor and electron-rich groups give good to excellent yields. It is noteworthy that the
halogenated aryl triflates can chemoselectively react with amines to afford halogenated anilines.
Anilines are very important motifs that have found wide
application in fluorescence probes,1 pharmaceutical and
agrochemical industry,2 photography systems,3 electronic
devices,4 and natural materials production.5 Traditional
nucleophilic aromatic substitution reactions (SNAr) of N-
nucleophiles are limited to only activated aromatic sub-
strates.6 The synthesis of anilines by Cu-mediated Ullmann
condensation often suffers from severe reaction conditions.7
In recent years, copper-mediated C-N cross-coupling reac-
tions of arylboronic acids with nitrogen-based nucleophiles8
and palladium-catalyzed C-N bond formation by exploiting
aryl halides or aryl triflates9 have emerged as powerful tools
for preparation of anilines. However, these literature methods
require catalysts, long reaction times, sensitive conditions,
and/or strong bases. The use of transition-metals and ligands
leads to the generation of waste and a number of hazards.10
The need for clean manufacturing processes demands the
development of new strategies for the preparation of anilines.
Microwave-assisted organic synthesis has attracted con-
siderable attention in the past decade.11 Microwave irradiation
often leads to a remarkable decrease in reaction time,
increased yields, and easier workup consistent with green
chemistry protocols and may enhance the regio- and stereo-
selectivity of reactions.12 More recently, it has been reported
that aryl halides could couple with amines to give anilines
employing microwave techniques in the presence of a strong
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10.1021/ol049963j CCC: $27.50 © 2004 American Chemical Society
Published on Web 02/21/2004