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2.9.2 General Procedure for the Preparation of Salts.
To a solution of 2-substituted aminopyrimidine (6 mmol) and α-bromoacetophenone
(7.2 mmol, 1.2 equiv) in acetonitrile (12 mL) was added 4-dimethylaminopyridine (6
mg, 0.05 mmol). After being stirred at 85 °C for 5 h, the reaction mixture was diluted
with acetone (20 mL) and the precipitate was filtered and washed with acetone (2×20
mL), ether (2×20 mL) and dried over P2O5 to give salt as a white solid.
10 new compounds were synthesized in similar manner.
2.9.3 General Procedure for the Preparation of Salts. (Microwave)
In a 50 mL microwave vial were successively dissolved 2-substituted
aminopyrimidine (6 mmol) and α-bromoacetophenone (7.2 mmol, 1.2 equiv) in
acetonitrile (12 mL) was added 4-dimethylaminopyridine (6 mg, 0.05 mmol). The
reaction tube was sealed, and irradiated in the cavity of a Milestone MicroSYNTH
microwave reactor at a ceiling temperature of 80 °C at 100 W maximum power for 30
min. After the reaction mixture was cooled with an air flow for 15 min, the reaction
mixture was diluted with acetone (20 mL) and the precipitate was filtered and washed
with acetone (2×20 mL), ether (2×20 mL) and dried over P2O5 to give salt as a white
solid. 34 new compounds were synthesized in similar manner.
2.9.4 General Procedure for the Preparation of 2-Amino-1H-imidazoles.
To a suspension of salt (2 mmol) in MeCN (5 mL) hydrazine hydrate (0.7 mL, 14
mmol of a 64% solution, 7 equiv) was added, and the mixture was irradiated in the
sealed Milestone MicroSYNTH microwave reactor for 10 min at a ceiling
temperature of 100 °C at 150 W maximum power. After cooling down hydrazine
hydrate was evaporated with toluene (3×20 mL). The resulting residue was purified
by column chromatography (silica gel; MeOH−DCM 1:4 v/v with 5% of 6M NH3 in
MeOH) to afford 2-amino-1H-imidazole as an amorphous material.
12 new compounds were synthesized in similar manner.
2.9.5 General procedure for the one-pot two-step microwave-assisted synthesis
of 2-amino-1H-imidazoles.
In a microwave vial (10 mL) were 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