Table 1.

Conditions for the reaction optimization.

Entry	p-TSA (mM)	Solvent	Time (h)	Temp.	Yield (%)
1	0	EtOH	16	RT	trace
2	0.25	EtOH	12	RT	55
3	0.25	EtOH	10	RT	55
4	0.5	EtOH	10	RT	62
5	0.5	EtOH	6	RT	70
6	0.5	EtOH	8	RT	95
7	0.7	EtOH	10	RT	60
8	0.7	EtOH	8	RT	65
9	0.5	MeOH	8	RT	65
10	0.5	EtOH:H2O (2:1)	8	RT	trace
11	0.8	EtOH: H2O (2:1)	8	RT	trace
12	0.5	EtOAc	8	RT	ND
13	0.5	Acetone	8	RT	ND
14	0.5	Dime. sulfoxide	8	RT	ND
15	0.5	Isopropanol	8	RT	trace

Reaction condition: The reaction (10 mL) was carried out with isatin (1 mM), dimethyl acetylenedicarboxylate (1 mM), 4-chloro 3-(trifluoromethyl) aniline (1 mM), and (0.5 mM) p-TSA acid catalyst. The isolated yield was calculated. Reaction completion was monitored by TLC. RT = room temperature. ND = not detected.