Synthesis of 2,4,5-trisubstituted imidazoles (6a–p) via the reaction of benzil (5a), aldehydes (4a–p) and NH₄OAc catalyzed by 3a^a.

Entry	Ar	Time (min)	Yield (%)	mp
				Found	Reported
1	C6H5	5	99	272–273	272–274 (ref. 18)
2	4-CH3O–C6H4	4	99	230–232	229–231 (ref. 18)
3	4-HO–C6H4	4	98	234–236	232–234 (ref. 18)
4	4-Me2N–C6H4	7	97	255–227	255–256 (ref. 18)
5	2-HO–C6H4	6	95	202–204	201–203 (ref. 18)
6	3,4-(MeO)2C6H3	6	98	214–216	213–216 (ref. 19)
7	4-CH3–C6H4	8	95	230–232	226–227 (ref. 18)
8	4-F–C6H4	8	96	260–262	262–264 (ref. 20)
9	4-Br–C6H4	5	98	265–266	261–263 (ref. 21)
10	2-Cl–C6H4	5	98	192–193	199–201 (ref. 21)
11	4-Cl–C6H4	7	97	263–265	262–263 (ref. 22)
12	2,4-Cl2C6H3	6	96	171–173	172–173 (ref. 20)
13	4-NO2–C6H4	7	96	242–243	239–242 (ref. 21)
14	2-Thienyl	5	99	255–257	254–256 (ref. 18)
15	2-Furyl	5	98	201–202	201–203 (ref. 21)
16	CH3	6	99	244–246	243–245 (ref. 23)

^aThe mixture of 4a–p (1 mmol), 5a (1 mmol), NH₄OAc (2.5 mmol) and 3a (5 mol%) in water (5 mL) was sonicated at 60 °C.