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Mol Divers
Table 2 continued
All the reactions were carried
out on a 4 mmol scale of
2-alkylaminopyrimidine 4 with
1.15 equiv of α-bromoketone 5
in MeCN (3 mL)
a Isolated yield after column
chromatography
Experimental section
Microwave irradiation experiments
15
16
17 N
A monomode CEM-Discover microwave reactor (CEM Corporation,
P.O. Box 200, Matthews, NC 28106) was used
in the standard configuration as delivered, including proprietary
software. All the experiments were carried out in sealed
microwave process vials (10 mL) at the maximum power and
temperature, as indicated in the tables. After completion of
the reaction, the vial was cooled to 50 ◦ C via air-jet cooling
before it was opened.
General procedure for the one-pot two-step microwaveassisted
synthesis of 2-amino-1H-imidazoles 1{1–18}
In a microwave, vial (10 mL) was successively dissolved
in dry MeCN (3 mL), the corresponding 2-aminopyrimidine
(4 mmol) and α-bromoketone (4.6 mmol). The reaction tube
was sealed and irradiated in a microwave reactor at a ceiling
temperature of 80 ◦ C and a maximum power of 50 W for
30 min. After the reaction mixture was cooled with an air
flow for 15 min, hydrazine hydrate (0.9 mL, 28 mmol of a
64% solution, 7 equiv.) was added, and the mixture was irradiated
at a ceiling temperature of 90 ◦ C and a maximum
power of 50 W for another 10 min. After the reaction mixture
was cooled, hydrazine hydrate was removed by distillation
with toluene (3 × 20 mL). The resulting residue was purified
by column chromatography (silica gel; MeOH-DCM 1:9 v/v
with 0.5% of 6 N ammonia in MeOH) to afford 1 as amorphous
solid.
18
N
N
N
N
N
H
N
N
N
N
H
N
H
N
H
Bu
OMe
Br
Br
Br
Br
O
O
O
O
SMe
NO 2
OMe
Bu
HN
HN
OMe
HN
HN
N
N
H
N
N
H
N
N
H
N
N
H
1{15}
1{16}
1{17}
1{18}
SMe
NO 2
OMe
Acknowledgments The support for this project was provided by the
Research Fund of the University of Leuven and by the F.W.O. (Fund
for Scientific Research—Flanders (Belgium)). E.D.S. is grateful to the
University of Leuven for obtaining a postdoctoral fellowship, and S.B.
to Erasmus Mundus External Cooperation Window Lot 15 India
(EMECW15) for obtaining a scholarship. The authors thank Ir.
B. Demarsin for HRMS measurements.
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