Investigating the influence of catalyst for the synthesis of (1a).^a.

Entry	Catalysts/solvents	Yieldb (%)
1	ETG-acetamide c	71
2	ETG-benzamidec	39
3	ETG-ZrOCl2·8H2Oc	Trace
4	ChCl : urea (1 : 1)c	58
5	ChCl : urea (1 : 2)c	66
6	ChCl : acetamide (1 : 2)c	67
7	ChCl : benzamide (1 : 2)c	45
8	ChCl : indole (1 : 2)c	61
9	ChCl : 2-aminobenzimidazole (1 : 2)c	37
10	ChCl : imidazole (3 : 7)c	Trace
11	ChCl : p-phenylenediamine (1 : 2)c	Trace
12	Tetraethyl orthosilicatec	Trace
13	Choline chloridec	10
14	Formic acidc	Trace
15	Ethyl acetate (EtOAc)d	Trace
16	Acetoned	Trace
17	EtOHd	Trace
18	None	Trace

^aReaction conditions: malononitrile (1 mmol), benzaldehyde (1 mmol), ammonium acetate (1.5 mmol), cyclohexanone (1 mmol).

^bIsolated yield by crystallization in ethanol (10–15 mL).

^cCatalysts (50 mg), solvent-free, at 80 °C.

^dSolvent (5 mL), ETG-acetamide (50 mg), at room temperature.