LETTER
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Synthesis of 2-Aminoimidazoles
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(12) Some reactions were complete within 18 h, although the
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(13) Typical procedure for a preparative scale reaction of 2 with
3: A 50-mL Schlenk bottle was charged with a toluene
solution (20 mL) of catalyst 1 (0.05 mmol), to which was
added 2 (1.0 mmol) and 3 (1.0 mmol). The flask was closed
in order to prevent the evaporation of amine. The reaction
mixture was then heated at 115 °C for 18 h. After removal of
the solvent, the residue was subject to flash column
chromatographic separation on silica gel (230–400 mesh) to
give 4.
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(14) CCDC-803540 contains the supplementary crystallographic
data of 4aa for this paper. These data can be obtained free of
charge from The Cambridge Crystallographic Data Center
(15) The conversion of guanidinoalkynes into imidazoles without
the assistance of a metal catalyst has been reported, see:
Oyler, A. R.; Naldi, R. E.; Stefanick, S. M.; Lloyd, J. R.;
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