Scheme 1
Ultrasound-assisted synthesis of 2-aryl-4-phenyl-1
H
-imidazoles.
A rapid and simple synthetic procedure to synthesize diversely substituted 2-aryl-4-phenyl-1H-imidazoles has been reported. Other salient features of this protocol include milder conditions, atom-economy, easy extraction, and minimum wastes. The present procedure may find application in the synthesis of biologically active molecules.
An expeditious green route toward 2-aryl-4-phenyl-1H-imidazoles
- Debasish BandyopadhyayEmail author,
- Lauren C Smith,
- Daniel R Garcia,
- Ram N Yadav and
- Bimal K BanikEmail author
Organic and Medicinal Chemistry Letters20144:9
DOI: 10.1186/s13588-014-0009-7
General procedure for the synthesis of 2-aryl-4-phenyl-1H-imidazoles
A
solution of the aldehyde (1 mmol) and threefold excess of ammonium
acetate (3 mmol) in methanol (2 mL) was placed in a B5510-DTH (Branson
ultrasonic cleaner; Model-5510, frequency 42 KHz with an output power
135 Watts; Branson Ultrasonics, Danbury, CT, USA) sonicator at room
temperature. The ultrasonic irradiation was started and a solution of
phenylglyoxal monohydrate (1 mmol) in methanol (1 mL) was slowly added
dropwise (by a syringe) to the above solution during a period of 15 min.
The resulting mixture was continued to irradiate as specified in Table 1.
After completion of the reaction (monitored by TLC with an interval of 5
min), the methanol was evaporated under reduced pressure and the crude
mass was extracted with ethyl acetate (2 × 5 mL). The combined organic
layer was washed with brine (10 mL) and water (10 mL) successively and
dried over anhydrous sodium sulfate. The extract was then concentrated,
and the crude product was purified using flash chromatography (neutral
alumina, 1% triethylamine in methanol) to afford pure compounds.
