Table 1.

Optimization of the Michael addition of 3-fluorooxindole 2a to the isatylidene malononitrile 1a.^a

Entry	Catalyst	Solvent	Time (h)	Yield (%)b	drc
1	Et3N	THF	2	99	>99 : 1
2	No base	H2O	12	nr	--
3	Et3N	Acetone	1	76	>99 : 1
4	Et3N	CH2Cl2	2	93	>99 : 1
5	Et3N	EtOH	1	97	>99 : 1
6	Et3N	THF:H2O (1:1)	2	99	>99 : 1
7	Et3N	EtOH:H2O (1:1)	2	98	>99 : 1
8	Et3N	H2O	3	99	>99 : 1
9d	NaHCO3	H2O	18	16	>99 : 1
10	Na2CO3	H2O	18	45	>99 : 1
11	K2CO3	H2O	18	78	>99 : 1
12e	Et3N	H2O	2	99	>99 : 1
13f	Et3N	H2O	7	81	>99 : 1

^aReaction conditions: 0.2 mmol of 1a and 0.2 mmol of 2a in 0.5 mL of solvent, 10 mol% of catalyst, 25 ^°C,

^bIsolated yield,

^cDetermined by ¹H and ¹⁹F NMR,

^d0.5 mL of sat. NaHCO₃,

^e20 mol% of Et₃N,

^f5 mol% of Et₃N.