Preparation of 1,2,4,5-tetrasubstituted imidazoles (8a–j) via the reaction of benzil (5a), aldehydes (4a–f), amines (7a–e) and NH₄OAc catalyzed by 3a^a.

Entry	Ar	Ar′	Time (min)	Yield (%)	mp
					Found	Reported
1	C6H5	C6H5	5	98	220–222	219–221 (ref. 18)
2	4-CH3–C6H4	C6H5	7	96	188–189	185–187 (ref. 18)
3	4-CH3O–C6H4	C6H5	5	96	183–185	183–185 (ref. 18)
4	4-Cl–C6H4	C6H5	6	95	161–162	160–163 (ref. 24)
5	4-Br–C6H4	C6H5	7	96	209–211	207–211 (ref. 18)
6	C6H5	C6H4–CH2	5	98	160–164	160–164 (ref. 24)
7	C6H5	4-CH3O–C6H4–CH2	5	98	150–153	150–154 (ref. 24)
8	4-CH3–C6H4	4-CH3–C6H4–CH2	5	98	132–135	132–135 (ref. 24)
9	4-F–C6H4	4-F–C6H4–CH2	6	96	158–161	158–162 (ref. 24)
10	4-CH3O–C6H4	4-CH3O–C6H4–CH2	6	96	152–154	152–154 (ref. 24)

^aThe mixture of 4a–f (1 mmol), 7a–e (1 mmol), 5a (1 mmol), NH₄OAc (1 mmol) and 3a (5 mol%) in water (5 mL) was sonicated at 60 °C.