Table 2.

Optimization of the double Michael addition reaction conditions.

Entry	Base	Solvent	Temperature (°C)	Yieldb (%)	Entry	Base	Solvent	Temperature (°C)	Yieldb (%)
1	K2CO3c	EtOH	23	21	7	K2CO3	Toluenee	23	31f.
2	K2CO3	EtOH	23	81	8	K2CO3	THF	23	Trace
3	K2CO3d	EtOH	23	56	9	K2CO3	H2O	23	Trace
4	–	EtOH	23	–	10	K2CO3	MeOH	23	Trace
5	DABCO	EtOH	23	20	11	K2CO3	DCM	23	Trace
6	NaOH	EtOH	23	Trace	12	K2CO3	EtOH	Reflux	36

^a0.5 mmol thiooxindole (1.0 eq), 0.5 mmol dibenzalacetone (1.0 eq), 0.5 mmol base (1.0 eq), 20 mL solvent.

^bIsolated yield.

^c0.025 mmol base (0.5 eq) was used.

^d0.5 mmol L-Proline (1.0 eq) was used as an organocatalyst.

^eMixture of cis and trans products was obtained.

^fIsolated yield of the cis product.